UK / V.R.C. 353 TECHNICAL DESCRIPTION

UK / V.R.C. 353 TECHNICAL DESCRIPTION
UK / V.R.C. 353
TECHNICAL DESCRIPTION
December 1978
RADIO SET RT-353
W F VEHICLE SET
Main Contractors: MARCONI SPACE AND DEFENCE SYSTEMS LIMITED (MSDS)
FOREWORD
In addition to manufacturing and supplying the UK VRC-353, Marconi Space and Defence
Systems Limited undertakes the prime contractorship of the Clansman VHF Vehicle Radio
System which includes the Control Harness, headsets, etc. As such it provides systems
proposals and planning facilities and is able to supply all the items necessary to meet
customers specific requirements in vehicies, both armoured and soft-skinned.
The UK VRC-353 is a VHF FM transmitter receiver providing two-way simplex voice
and data communication.
Although designed primarily for vehicular multi-set installation, in conjunction with the
Clansman harness it is equally suitable for applications such as fixed or portable ground
station and unattended repeaters. It may be used with a variety of specially-developed
antenna systems. There are built-in facilities for remote control of transmitheceive, operator
intercommunication and local or remote automatic re-transmission with or without the harness.
The set, which is sealed, may be stored or transported un-packaged in con&tions of high
humidity or low air-pressure, and will operate in extremes of temperature fully exposed to
rain, dust or solar radiation. Its performance is unaffected by wide voltage variations of battery,
and it incorporates protection against high-level supply transients.
The UK VRC-353 is interoperable with the Clansman VHF manpack sets and with equipment
now in service, such as the C-42 No. 2, the VRC-I2 and the SEM 25, and it meets NATO
specification for a 30 km (20 mile) set.
DESIGN FEATIJRES
Ease of operation
A single channel-setting switch controls simultaneously the transmitter, the receiver and the
antenna tuning unit, and re-tuning from any frequency to any other is completed within
ten seconds. Automatic gain control holds the modulating level constant for microphone inputs
corresponding to any speakmg level from a whisper to a shout.
Frequency stability
The digital synthesiser with its high stability, temperature compensated master oscillator
maintains the selected operating frequency within 5 parts per million at any ambient
temperature down to -40 C.
Immunity to interference
The extremely high selectivity and the low spurious radiation allows sets separated in frequency
by only 5% and with aerials 2 metres (6 ft) apart to be operated, at full power with negligible
mutual interference.
Channel availability
The stability and selectivity of the set make it possible to use 25 KHz channel spacing without
restriction of performance, but a 50 KHz mode is also provided so that the set is interoperable
with equipment now in service and those projected for future NATO use.
Versatility
A switch, incorporated in the front panel, enables the equipment to be operated in either an
analogue voice mode or in a digital data mode, with data rates up to 20 kilobits per second.
Microminiaturization
The use of microminiature components and techniques enables high performance to be
achieved in about one-third of the volume of comparable sets now in service, and greatly
increased reliability.
Ruggedness
The set is engineered to withstand rough handling and transport by land, sea or air unpackaged,
and to operate in the shock and vibration conditions encountered in fighting vehicles.
Ease of Maintenance
Modular construction allows faults to be located to replaceable sub-units, the more expensive
of which may be repaired at base workshops.
Comprehensive facilities
All circuitry required to provide the control and operational facilities for the various types of
installation within the equipment, eliminating the need for extra units.
ENVIRONMENTAL SPECIFICATION
The equipment has been designed to meet the requirements of the British Defence Specification
DEF. 133 Class L3 (Ground Equipment, exposed and immersible, unpackaged). Its Ambient working
temperature range is -40 C to +55 C and in addition it will withstand the heating effects of solar radiation.
The storage temperature range is -40 C to +65 C. It is designed to meet the operational conditions in
wheeled and tracked land vehicles, travelling on surfaced and unsurfaced roads and open country,
and transported by land, sea and air. It will withstand operational shocks in armoured fighting vehicles
due to the impact of non-penetrating shells on the vehicle armour, and delivery by normal parachute
techniques. The equipment is capable of operation and storage under conditions of heavy driving rain,
salt spray, high wind, driving dust, driving snow and humidity in excess of 95% at 30 C.
The equipment can be operated and stored at altitudes of 2,500 metres (8,200 ft) and can be transported
in unpressurised aircraft at altitudes of 8,500 metres (25,000 ft). The equipment will stand immersion to
a covering depth of 1.6 metres (5 ft) of water for at least two hours. It is immune to the corrosive effects
of acid spray from secondary batteries and it is also unaffected by severe contamination by fuel oils,
hydraulic oils and lubricating fluids.
(ii)
BRIEF TECHNICAL SPECIFICA'I'ION
General
Frequency
Range
Number of
RF Channels
Channel
Spacing
Frequency
Setting
Frequency
Stability
Radio System
Ambient
Temperature range
Size
Weight
Power Supply
Power
Consumption
30 - 75.975 MHz
30 Km (20 miles).
1840 at 25 KHz spacing.
920 at 50 KHz spacing.
25 KHz with 5 KHz peak deviation.
50 KHz with 10 KHz peak deviation.
Selected by switch on the fiont panel.
Manually by switch on front panel.
+I- 5 parts per million (380 Hz maximum)
from all causes.
VHF FM simplex voice or VHF FM data.
-40 C to +55 C.
Height 21.7 cm (8.5 in), width 24.2 cm
(9.5 in), depth 25.9 cm (14 in).
22 kg (about 501b).
Will work with battery voltages between
2 1.5V and 34V, with superimposed ripple
of 4 volts peak to peak and short duration
spikes of +/- 600 volts. There is no DC
connection between supply terminals and
any other terminals andlor the case.
Typical current consumption: 3A on
receive, 10A on transinit at 24V DC.
Transmitter
Output Power
Harmonic
Suppression
Spui-ious
Suppression
Full-power output of SOW into resistive
load of 5OR and 35W into a v.s.w.r. of 2.1.
Output power can be reduced by a switch
to 15W, 1W or 100inW.
The transmitter will continue to function
without damage into any load impedence.
Harmonic frequencies up to 500 MHz are
at least 50 dB below the wanted output.
The spurious output in any 25 KHz
channel 5% or more off-tune is at least
120 dB down on maximum transmitter
power except in channels which are
harmonics of the transmitter frequency.
(iii)
AF Input
AF Response
Full deviation of the transmitter is produced
by the signal level of 0.5 mV - 20 mV.
300 Hz: -3 dB, 1000 Hz: OdB, 3000 Hz:
-3 dB
Receiver
Sensitivity
Selectivity
Image Response
IF Suppression
Interfering
Signal Rejection
Receiver
Protection
AF output
AF Response
Squelch
Less than 0.5 uV r.m.s. e.m.f. for 6 dB
S/N at 1000 Hz modulation frequency and
N full deviation.
Rejection of the receiver at the centre
frequency of all channels, except that to
which the receiver is tuned is greater than
100 dB.
At least 100 dB down on main response.
Better than 100 dB.
A sensitivity of 10 dB less than that defined
above can be achieved in the presence of an
unrnodulated interfering signal +/- 5% off
tune and of e.m.f. 20 volts r.m.s.
No damage will be caused by a signal on the
antenna terminal of e.m.f. 100 volts r.m.s.
and at any frequency within the tuning
range.
Local Headset: 100 mW maximum.
300 Hz: -3 dB,1000 Hz: 0 dB,3000 Hz:
-3dB.
Fully automatic.
CLANSMAN RADIO UKNRC 353
CONTENTS
INTRODUCTION
Role and Purpose ......................................................................
Main Parameters
.............................................................
Operational Parameters
Physical Parameters
................................................................
...............................................................
Electrical Parameters
.......................................................
Remote Control Parameters
Power Supply Parameters .............................................................
.....................................................
Coding and Identification Data
Testing and Repair Facilities ........................................................
BREF DESCRIPTION
Construction ............................................................................
..................................................................
Outline of Working
Controls and Facilities ..................................................................
Frequency Selection Switch (1a)S 1 ...................................................
Mode Switch (la)S2 ....................................................................
Power Switch (la)S3 ....................................................................
Test Switch (la)S4 ......................................................................
Gain Switch (la)S5 .....................................................................
Remote Switch (la)% ..................................................................
DC Input Plug (1a)PL 1 .................................................................
Audio Sockets (1a)SKl, (1a)SK2 .....................................................
Harness Plug (la)PL2 ...................................................................
Turf Connector (1a)SK3 ................................................................
ANTITurf Connector (1a)SK4 .........................................................
Remote Terminals (1a)SKS. (1a)SK6 ................................................
Indicator Lamps ..........................................................................
Test Meter (1a)ME 1 .....................................................................
Alam Indications ........................................................................
TECHNICAL DESCRIPTION
T e c h c a l Notes ..........................................................................
Unity Gain Amplifier ....................................................................
Identification of Signal Logic ..........................................................
Turret Band Selection ...................................................................
Selection Sequence ......................................................................
Incorrect Frequency Setting .............................................................
Frequency Control .......................................................................
RECEIVER
RF Amplifier ..............................................................................
Local Oscillator ..........................................................................
Signal Mix .................................................................................
IF Unit (5) .................................................................................
. .
AudioITone Circu~ts .....................................................................
Squelch System (85Hz) .................................................................
Tone Detection (1SO&) ................................................................
Audio Routing to Phones ...............................................................
TRANSMITTER
Modulation Routing .....................................................................
Transmitter Modulation .................................................................
PA On Command ........................................................................
Power Amplifier .........................................................................
PA Output .................................................................................
Transmit Commands ....................................................................
Remote Switch Control Functions ...................................................
Local .......................................................................................
Remote ....................................................................................
Auto ........................................................................................
Break In ....................................................................................
Intercommunication (IC) ................................................................
Call .........................................................................................
Temperature Sensor .....................................................................
Control of T U U M T N 4 0 2 ............................................................
Power Supply Unit .......................................................................
Voltage Control ...........................................................................
Over volts .................................................................................
Over current ..............................................................................
The Switching Inverter ..................................................................
Control of Equipment in DATA Mode ...............................................
Data Reception ............................................................................
Data Transmission .......................................................................
Associated Literature ......................................................................
RADIO CONTROL HARNESS SYSTEM
Summary of Terms Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Systems ........................ .
.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Units for Two Radio System ...........................................................
Units for Three Radio System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ancillary Items . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Self-Propelled Artillery Communication Harness .................................
.
.
Audio Anclllaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Associated Literature ....................................................................
FIGURES
Page No:
Figure No:
Dimensions ..................................................................
Controls and Connections ..............................................
Signal Identification and Logic Symbols .............................
Output Functions PA On ..................................................
Turret Control Block Diagram .............................................
Simplified Turret Band Select .............................................
Complete Control Diagram RT353 Receiver ............................
Coarse Tuning of Receiver Local Oscillator
and all RF Tuned Circuits ..................................................
Fine Tuning of Receiver LO ...............................................
Inching Action .Receiver LO ..............................................
Transmitter AFC Block Diagram .........................................
Frequency Control Block Diagram .......................................
V1 with TR1 in Cascode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front End Protection ........................................................
SquelchlTone Circuits ......................................................
PA Bias .......................................................................
Auto-Rebro Link .............................................................
Power Supply Unit ...............................................
Interconnecting Box-:! Radio (032) ......................................
Crew Box 2 Set (CB2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Commanders Box Fixed (CBF) ...........................................
Drivers Box (DB) ...........................................................
Two Radio Harness Control System ......................................
(vii)
CLANSMAN RADIO RT-353
INTRODUCTION
WARNINGS:
H i ~ Voltag
h
This equipment uses an internal supply of +6OOV d.c. and great care must
be taken to avoid contact with this line.
Beryllium
This equipment uses components containing beryllium or beryllium-oxide.
In certain circumstances they can constitute a health hazard. Before
working- on the equipment consult Gen KO50 - Beryllium Toxic Hazard in
Electronic Equipments - which gives general information, handling and
disposal instructions.
COOLING AIR
The cooling air flow through this equipment must not be obstructed at the
back or front of the equipment.
ROLE AND PURPOSE OF EOUIPMENT
1. The VRC 353 is one of the CLANSMAN range of radio equipments, designed
for use in vehicle installations or as a ground station.
2. The RT 353 is a VHF (FM) transmitterlreceiver which covers the frequency
range 30 to 75.975 MHz and is capable of transmitting and receiving speech, data,
telegraph and facsimile signals, the latter being via an applique unit.
3. An identiQing modulation of 150 Hz is superimposed on transmissions
(except in the WIDE or DATA mode) to permit interworking with equipments of
diverse origin and for use during automatic rebroadcasting working.
4. The RT 353 is capable of being used in three basic configurations:
a. In a harness system (Data or Analogue).
b. Remote operation, using a single pair field telephone cable up
to 3 krn long terminated in a remote handset, another radio or special
applique unit. When connected to another suitable radio, an automatic
rebroadcast link can be established. Telegraph signals are accepted
via the remote terniinals from an appropriate Telegraph Radio L m .
c. Local operation via the AUDIO connectors on the front panel.
5. In harness or remote operation, the audio routing (send and receive) and
transmitlreceive switching are remotely controlled, but frequency and mode
selection remain on the radio. This provides single frequency SIMPLEX
communication.
6. The RT 353 is operated in conjunction with the Adaptor RF Antenna Tuning
(ARFAT) and the Tuner Unit Automatic Antenna MatchingiTN 402 - TUAAMiTN402.
MAIN PARAMETERS
7. Operational Parameters
Range: Up to 50 km with a recommended vehicle antenna.
When used in a static role greater distances may
be obtained by the use of an elevated whip or
inverted "V" antenna.
8. Phvsical Parameters
Height:
Width:
Depth:
Weight:
2 15 mm (8 112 in)
240 mm (9 112 in)
355 mm (14 in)
22 kg (50 Ib)
9. Electrical Parameters
30 ME-h to 75.975 MHz in three discrete bands:
Frequency Range:
30 MHz - 40.975 MHz
41 MHz - 55.975 MHz
56 MHz - 75.975 MHz
Band 1:
Band 2:
Band 3:
Frequency Stability: +/- 5 ppm
Intermediate Frequencies: 1. 9.6875 MHz
2. 312.5 kHz
No. of channels:
1840 at 25 kHz spacing
920 at 50 kHz spacing
Receiver sensitivity:
6 dB (s+n/n) for 0.5 uV rms emf input,
modulated by 1 kHz at 5 M-lz deviation
(NARROW) or 10kHz (WIDE)
Sensitivity such as to give error rates
specified for corresponding input levels of
unfiltered data at 16 Kb/s.
Analogue:
Data:
I
Signal Level (rmslemf)
I
Error Rate
I
Less than 0.3%
Less than 4%
Less than 14%
Less than 26%
Receiver selectivity: Rejection greater than 80 dB on all channels
other than that selected.
I
AF Output:
Analogue: For input of 0.5 uV rms
emf modulated by lKhz at 5 kKz
deviation (NARROW) or
10 kHz (WIDE)
2.7V nns (nominal into 75 ohms at
AUDIO sockets with GAIT4 control
fully clockwise. 1.7V mls (nominal)
into 75 ohms at HARNESS socket,
independent of GAIN control.
0.75V rms (nominal) into 300 ohms
at REMOTE terminals, independent
of GAIN control
Sidetone level: For input of
30 mV rrns emfat 1 lcHz to
AUDIO socket pins A and B
2.75V m s (nominal) into 75 ohms
at AUDIO sockets with GAIN
control fully clockwise.
Data: For input of 0.5 uV rrns
emf modulated by 2 kHz at 4 kHz
deviation (NARROW DATA) or by
2 kHi at 8 kHz deviation (WIDE
DATA)
900 mV emf peak-to-peak (nominal)
from a nominal 500 ohms at HARNESS
connector pin D.
Squelch operation:
By 85 Hz internal modulation of
local oscillator.
Transmitter power output:
100 mW to 50W (nominal) according
to setting of POWER switch, into
50 ohms.
Modulation Sensitivity:
Analogue:
5 kHz (nominal) peak deviation (NARROW)
10 kHz (nominal) peak deviation (WIDE)
for a 1 kHz at 1-40 mV rms emf signal
to AUDIO connectors pins A and B with
GAIN control to mid-position, or for a
I kHz at 80 mV - 4V rms emf balanced
input to REMOTE terminals or HARNESS
connector pins A and B independent of
GAIN control.
Data:
4 kHz(nominal) peak deviation (NARROW),
8 kH (nominal) peak deviation (WIDE),
for a binary input of a regular 0000 1111
pattern at 16 kbls (WIDE DATA) or 8 kb/s
(NARRROW DATA) at a level of 3.2V emf
peak to peak at HARNESS plug pin A
(wrt pin B) from a source impedance of
600 ohms (nominal)
Tone:
1.45 kJ3z (nominal) peak deviation(NARR0W)
2.9 kHz (nominal) peak deviation (WIDE)
Side tone:
True, by leakage across the antenna
10. Remote Control Parameters. The radio will transmit when a d.c. current
of between 8 and 11 mA is drawn from the remote terminals. The radio will
generate a call tone of 2 kHz (nominal) when a d.c. current of between 20 and
35 mA is drawn from the remote terminals. The remote user has false sidetone
generated in the remote headgear.
11. Power Supply Parameters. The radio will perform to specification for
d.c. inputs between 21V - 33V d.c. (24V d.c. nominal).
Current Consumption:
12A maximum at 28V on transmit
9A nominal at 28V on transmit
3A +/- 1A on receive.
12. Coding and Identification Data. Table 1 lists the assemblies/sub-assemblies
which together form the equipment.
Assembly
Number
1
Designation
Chassis Wired Assembly
Principal items and
sub-assemblies
Heat Exchanger, Front Panel complete
with switches/sockets/plugs, internal
plugs/sockets and wiring harness.
Front Panel Components
Meter control
Blower drive
Audio pre-amplifier
+28V supply filter
TURF filter
Gain control
Crystal oscillator
TUAAM Control Board
Printed Circuit Board
Pack
Tuning Board
Modulator Board
Control Board
Audio Board
Motherboard
Receiver
Chassis and components
Front-end protection
Control IF
Signal IF
Signal mixer
Buffer Amplifier
Turret drive - 3g TS 1
p.e.c./relay and connector
Local oscillator
Filter
Varactor amplifier
Turret lids r.f.
Turret lids band- ass
Assembly
Number
Designation
sub-assemblies
(4a)
Chassis and components
(4a)
TS 1 End Filter
(4a)
TS3 Power amp component
plate
(4a)
TS4 High volts end plate
(4b)
Varactor plate
(4c1) Control Board 1
(4c2) Control Board 2
End plate TS 1
TS2 Harmonic Filters
Turret drive
Turret lids including
Oscillator
Transmitter
Temperature sensor
IF Amplifier
Main chassis and components
Relay assembly
Amplifier
Synthesiser
Buffer amplifier
Fixed divider
Variable divider
Comparator
Power Supply
Chassis and components
Control panel
Regulator drive
Tunnel diode
HV diode
Choke section
Output section
Blower drive supply chassis
Blower drive p.e.c.
(7n 1)
(7112)
Table 1 - RT 353 Assembles/Sub-Assemblies
14. Testing and Repair Facilities.
a. Unit Repairs. The R?' 353 is a sealed equipment and consequently no
attempt should be made at Unit level to cany out repairs other than the
exchange of loose CES items, and the replacement of external components.
b. Field Repairs. Repairs at Field level will be the replacement of any
of the 6 items designated CENTREMS (see Table 2) and the replacement of
discrete components on the 3 major assemblies. In addition, repairs to
the Front Panel and Chassis Wired Assembly will be by replacement of
individual components or 'throwaway' PECs.
c. Base Repairs. Other than complete overhaul of the equipment. Base
Workshops will be responsible for the repair of faulty CENTREMS backloaded
from Field Workshops.
5
I
Designation
I
Amplifier Intermediate Frequency (Unit 5)
Panel Electronic Circuit (Tuning Board 2a)
Panel Electronic Circuit (Modulator Board 2b)
Panel Electronic Circuit (Control Board 2c)
Panel Electronic Circuit (Audio Board 2d)
Synthesiser, Electrical Frequency (Unit 6)
Table 2 - RT 353 Designated CENTREM Items
BIUEF DESCRIPTION
CONSTRUCTION
15. The equipment is housed in a rectangular cast aluminium alloy case and
secured by five dowel bolts, one at each comer of the equipment front panel
and one centrally located in the rear wall of the case. The rear wall
sealing bolt includes a sealing washer.
16. Sealing is provided by toroQal rubber sealing rings between front
panel and case and at each blower outlet in the rear wall. Additional
sealing is provided at the blower outlets by a rubber and metal seal located
beneath the sealing rings.
17. Excessive internal temperatures are limited by the use of a heat exchanger.
Air is drawn into the equipment via the front panel grille passed through a
hollow metal chassis (heat exchanger) on which all the main assemblies are
mounted, and exhausted to the rear by two blower motors.
18. A carrying handle, retained in the stowed position by a spring clip,
an earth bonding terminal and a cable stripper are mounted on the front
panel. A cartridge dessicator and seal test plug are located in the rear
wall of the case.
19. Two retaining blocks, secured to the rear bottom comers of the case,
provide the method of retaining the equipment on CLANSMAN mounting bars,
the bars engaging with slots machined in the bottom of the case.
Fig 1. Dimensions
OUTLINE OF WORKING
20. The RT 353 VHF transmitter - receiver operates in three discrete bands
within the operating frequency range by automatic band selection controlled
by an electrically - controlled mechanical turret system, there being one
turret for the receiver and one for the transmitter.
2 1. A band change is initiated by the front panel frequency switch which
also controls a frequency synthesis loop system to maintain tuning to the
selected frequency to within +/- 5 ppm, the loop ensures that the local
oscillator is phase locked to a crystal reference frequency.
22. The Tuning Unit Automatic Antenna Matching TN402 (TUAAM/TN/402) is
automatically tuned to the required frequency using frequency and phase
detectors and servo amplifier driven motors. Control signals from the RT 353
are used to operate the Attenuator RF Antenna Tuning (AFAT).
CONTROLS AND FACILITIES (Fig 2)
23. The functions of the RT 353 are controlled by six front panel switches
(1a)Sl - (la)S6, control and information signals being passed to and from the
equipment by eight front panel connectors, (la)PL2, (1a)SKl - (la)SK6.
Fig 2. Controls and Connections
24. Frequency Selector Switch (1a)Sl The inner selector determines which
decade will be varied by the outer knob. Thus the two left-hand windows select
all MHz settings between 50 and 75 inclusive, and the two right-hand windows
can be set to between ,000and .975 in steps of ,025 MHz. A slipping clutch
becomes operative after the maximum or minimum is reached on each of the
indicator drums. The minimum of the 10 MHz drum is '0'. Thus by counting
the click positions from zero, the desired frequency can be obtained without
visual observation.
25. MODE Switch (la)S2
facilities:
A five position switch providing the following
WIDE DATA
NARROW DATA
WIDE
:
WTDE TONE
NARROW
:
:
:
:
Data operation of 50 kHz channel spacing
Data operation of 25 kHz channel spacing
Analogue operation at 50 kHz channel spacing
with no 150 IHz tone modulation.
As for WJDE but with 150 Hz tone modulation
Analogue operation at 25 kHz channel spacing
with 150 Hz tone modulation,
26. POWER Switch (la)S3 A seven position switch providing the following
facilities:
complete equipment switched off.
r.f. power output level 100 mW nominal.
r. f. power output level 1W nominal.
r.f. power output level 15W nominal.
r.f. power output level 50W nominal.
Equipment will not transmit except during tuning
sequence of T U W T N 4 0 2 when the power output is
absorbed by a dummy load in the tuner.
The 28V supply to the T U W T N 4 0 2 is interrupted.
This causes the T U A M T N 4 0 2 to start a tuning
sequence when the switch is return from this
position. Switch biased to the 0 position.
OFF
m
1W
15W
50W
0
TUNE
27. TEST Switch /la)S4 A ten position switch providing the following
facilities:
LPS OFF
:
FANS OFF
:
28V SUPPLY
:
RX SIG
:
TX O P
:
All lamps off. Test Meter (1a)MEl indicates received
signal strength.
Fans and lamps off, transmitter inhibited. Test
Meter indicates received signal strength.
Meter indicates supply voltage on marked scale,
whenever the 28V supply is connected.
Test Meter indicates received signal strength on
arbitrary scale.
Test Meter indicates whether the transmitter output
valve is drawing the current appropriate to its
power setting. Correct operation is indicated by
pointer in green area (approx 213 f.s.d)
AFC TX
Test Meter indicates whether the transmitter
frequency control loop is operatmg correctly.
Meter measures d.c. level from loop which will
be OV(nomina1) when phase locked. Pointer should
be central +I- 3 divisions
Test Meter indicates whether synthesiser is locked.
For correct operation meter reads right of centre.
For incorrect operation meter reads left of centre.
Test Meter indicates whether the radio is overheated.
For normal operation meter reads right of centre.
For overheat meter reads left of centre.
Test Meter indicates whether ARFAT temperature is within
limits. For normal operation meter reads right of centre.
For incorrect operation meter reads left of centre.
SYNTH
TEMP
TURF
In this switch position the TEMP and ARFAT alarms
are over-ridden, muting by the squelch circuit is
overridden and the cooling fans are switched on.
The switch is biased to the ARFAT position. Test
Meter indicates whether Transmitter is locked,
correct operation meter reads right of centre.
OVERRIDE
28. GAIN Switch (la)% A ten position rotary switch whch simultaneously
controls the audio level to the AUDIO sockets and the audio level from the
microphone pre-amp such that increasing the level of one decreases the level
of the other.
29. REMOTE Switch (la)S6 A six position switch giving the following
facilities:
LOCAL
:
REM
:
AUTO
:
BK-IN
:
I.C.
:
CALL
:
Control of the radio is by a CLANSMAN headsethandset
connected to either of the AUDIO sockets.
Control of the set, in addition to the local operator,
is by either a CLANSMAN remote handset connected to the
REMOTE terminals or a CLANSMAN harness installation
connected via the HARNESS socket.
Automatic rebroadcast available using a further radio
connected via the REMOTE terminals or via an appropriate
system connected to the HARNESS socket.
Supervisory facility for the local operator preparing
for automatic rebroadcast working. Automatic
rebroadcast is inhibited and operation of the local
pressel causes both the local and the remote controlled
sets to transmit. With the pressel released, the operator
hears both the local and the remote received signals.
Intercoinmunication between the local operator and
the remote user without r.f. transmission.
Audible tone heard by local and remote users.
'Call' current is drawn from the remote lines.
The switch is biassed to the IC position.
30. DC Input Plug (1a)PLI A two-pin plug with '+' and '-' identification.
3 1. AUDIO Sockets ( 1a)SKl (upper) and (la)SK2 (Lower) Two 7-way sockets for
local handsets and headsets.
Pin:
Mic +
Mic Supply ( 2 W
phone
earth (return for C,D,F and G)
pressel
phone
A
B
C
D
E
F
G
The supply at Pin C is through a 470 ohm resistor to prevent damage due to
accidental short circuits. Pin D and G are connected together inside the
equipment, pin B is a separate mic earth return to avoid unwanted audio feedback.
32. HARNESS Plug ( la) PL2 A 7-way plug for operation via CLANSMAN harness.
Pins A and B are connected in parallel with the upper and lower REMOTE terminals
respectively when the RT 353 is operated in the analogue mode.
Analogue pin:
A
B
C
D
E
F
G
Mic +
Mic earth
phone +
phone not used
earth
Data pin:
A
B
C
D
E
F
G
data input
transmit/ receive command
earth
data output
signal strengthlsquelchltone output
clear speech command
earth
33. TURF Connector ( 1a)SK3 A 12-way double density pattern 104 connector for
control of TUAAM/TN402.
Pin:
A)
B
c>
D1
E)
H)
K)
L
M
0
P
S
not used
ARFAT Temperature
Tuner keyline
Silent tune
earth
+28V
34. A current not exceeding 100 mA may be drawn from Pin S whilst the set
is transmitting on full powerj up to 4A may be drawn whilst the set is not
transmitting, but if the set is made to transmit whilst such a current is
being drawn the PSU will trip out. The supply can be interrupted by the
POWER switch.
35. Pin L will be at logic 1 for ARFAT temperatures within limits, this
will change to logic 0 (overheat) to produce an ALARM condition. Pin M
is an input from the TUAAM/'T?\T402.When connected to earth (Pin P) it causes
the radio to transmit at a fixed r.f power level (50W) for TUAAM tuning.
Pin 0 is open circuit except when connected to OV by the POWER switch to cause
the T U W T N 4 0 2 to absorb all transmitted power in a dummy load during tuning.
36. ANTITURF Connecter(la)SK4. A BNC pattern 16 connector for RF input
and output.
37. REMOTE Terminals ( I a)SKS('+') and (1a)SKb. Spring terminals suitable for
connecting to stripped wire, used for the remote handset or remote radio. The
equipment contains 'SEND' and 'CALL' detectors which operate at pre-determined
line current threshold levels. The behaviour of the current detector is shown
below:
FUNCTION
MUST NOT CALL
MUST
NOT
SEND
MAY CALL
OR SEND
MUST CALL
KJST NOT SEND
(SHORT
CIRCUIT
CURRENT)
(SEND CURRENT)
I
0
i
LINE CURRENT (mA)
Similarly, when set for AUTO operation, and not already responding to currents
drawn from the terminals, the equipment draws send current from the line in
response to the appropriate r.f. input as defined below:
MODE switch setting
NARROW
WIDE TONE?
WIDE
Required response to r.f
150 Hz modulation detected:
150 Hz modulation detected.
Squelch operated
38. Indicator Lamps The equipment has a red indicator lamp (la) LP1 which is
illuminated when the set is transmitting. The meter and tuning scale are
illuminated by internal white lamps. All illumination is inhibited in the
LPS OFF, FANS OFF AND OVERRIDE positions of the TEST switch.
39. Test Meter (1a)MEl A test meter is provided, marked 16 to 32V. The
right-hand sector of the scale (24 to 32V) is colowed green and the left-hand
sector coloured red. Divisions are in 2V steps.
The test meter monitors:
a.
b.
c.
d.
e.
f.
g.
h.
Supply voltage.
Received signal strength.
Transmitter power.
Transmitter frequency control loop.
Transmitter lock.
Synthesiser
Temperature.
ARFAT Temperature.
40. Alarm Indications Certain equipment fault conditions produce alarm
indications in one of two ways:
a. Frequency dial illumination flashng on and off (at approx 1 Hz)
and all audio outputs interrupted (at approx 1 Hz).
b. Non-illumination of TX lamp when transmit commanded in other
than LPS OFF, FANS OFF and OVERRIDE positions of TEST switch (la)S4.
4 1. Transmitter working is inhibited in the following conditions:
a.
b.
c.
d.
Failure of transmitter phase locked loop.
Failure of frequency synthesis giving incorrect frequency output.
ARFAT Overheat.
Equipment overheat.
Indication of (a.) is absence of transmit lamp indication with the TEST switch
on other than LPS OFF, FANS OFF and OVERRTDE posistions and by meter reading
in the OVERRIDE position. Indication of (b.) to (d.) is primarily by flashing
lamps together with an audible indication in any earpiece or loudspeaker
connected to the equipment. The TEST switch then allows the cause to be
located by interpretation of meter readings.
42. In the event of a cooling failure a thermostat switches off the transmitter.
If the temperature continues to rise, a second thermostat will switch the
equipment off before overheating causes any damage. Certain alarm conditions
may be overridden, & the equipment can be operated in the ARFAT or equipment
overheat alarm condition if urgently required. Setting TEST switch S4 to OVERRIDE
cancels the alarm output from the control logic circuits and lifts the audio
muting on Audio Board 2d. The blowers are switched on regardless of prevailing
temperature conditions, the front panel meter indicates whether the transmitter
is locked, and the front panel TX lamp is switched off.
TECHNICAL DESCRIPTION
TECHNICAL NOTES
43. The logic circuits within the equipment employ conventional positive logic techniques
with intergrated circuit 'chips' providing elements such as Nand gates, inverters, bistables,
monostables, etc. The symbols employed in this precis together with their associated truth
tables are shown in Figure 3.
44. Unitv Gain Amplifier This is a gated amplifier specially developed for the RT353
being used on both Audio and Modulator Boards. The amplifier exhibits the properties
of a linear gate with both normal and negated inhibiting inputs as the controlling
influences. A logic I input to the normal inhibiting gate will prevent an output signal
representing I whatever the level of the other inputs. A logic 0 input to the negated
inhibiting gate will have the same effect.
45. The 'through' signal paths are at an audio frequency at a level of +/-2 volts
and not switched logic levels; the gain as the name implies is unity.
SIGNAL, IDENTIFICATION AND LOGIC SYMBOLS
46. Identification of Simal Lopic A signal is identified on the Logic Diagrams by
a 'name', the name of the signal relating to the defined I-state. The convention 'name'
with a bar over the top refers to the logic negation of the same signal.
eg SYNC
=
the logic negation of SYNC
Logic Symbols employed in this Precis
TRUTH TABLE
Buffer
Inverter
NAND Gate
INPUT
JK Element
with direct
clear
Clock
K
I
AFTERCLOCK PULSE
J K C R
Q
1
0
0
1
-
1
0
0
1
1
-
1
1
1
1
0
+
D
Q
0
+
1
*
*
0
1
* Depends on last previous Q and Q state (output states reverse)
+ Output states remain as for before the clockpulse
Fig 3. Signal Identification and Logic Symboh
47. The output function P.A. ON (Fig 4) is only present when TRANSMITTER
LOCK AND SYNTHESISER LOCK AND (OVERRIDE
ARFAT TEMP AND TEMP)
are present as inputs.
..
TX M C K
,
TX M C K
.
I
.
I
I
TEMP
.-
Fig 4. Output Function - PA On
TURRET BAND SELECTION
FREQ SETTING
SWITCH
%
r
TX TURRET
CONTROL
I
tt
m
TX TURRET
INHIBIT
TX TURRET
= TURRET LIDS
m
RX TURRET
CONTROL
INHIBIT FREQ
CONTROL
RX TURRET
Fig 5. Turret Control Block Diagram
48. The frequency range of the RT353 is divided into three discrete bands:
Band 1 --- 30 - 40.975MHz
Band 2 --- 41 - 55.975MHz
Band 3 --- 56 - 75.975MHz
49. Each band has discrete RF tuned circuits and oscillator circuits, the
components of which are mounted on the turret lids. The transmitter lid has
one turret per band each containing the P.A. rf timed circuits and oscillator
components (less main timing capacitor). The receiver turret has two lids per
band, the turret lid RF, containing two rf tuned circuits associated with
the first rf amplifier, and the 'turret lid bandpass', containing a further
three rf timed circuits associated with the second rf amplifier and the local
oscillator tuned circuit (less main tuning capacitor).
$0. The receiver and transmitter turrets are each driven from band to band by
individual dc electric motors under the control of associated circuits. The
two control systems are interconnected to ensure that whilst the receiver
turret is timing the transmitter is locked stationary. A control output also
holds the frequency control system inhibited until the receiver turret has
completed tuning.
5 1. Band change is automatic and is initiated as the frequency selection
switch (FSS) is changed from a frequency lying within one band to a frequency
within another band. The system is earth seeking.
Fig 6. Simplified Turret Band Select
15
52. Fig 6 shows the system in the quiescent condition having selected Band 1.
If the frequency selection switch is now changed to a frequency in Band 3 the
following sequence occurs:
a. OV is removed from Band 1 line from FSS and switched to Band 3.
b. The two control relays 3RLA12 and 4RLA 12: de-energise.
c. Contact RLA-I places OV (logic 0) on one input of a 2 input NAND Gate
3TR1 (inhibit Tune).
d. Contact RLA-2 places OV on one side of the Rx turret drive motor 3M1,
the other side of which is permanently connected to +28.
Motor 3Ml thus rotates.
e. Contact 4RLA-I moves over awaiting OV to be placed on it by 3RLA reenergizing after the Rx turret has tuned.
f. Motor 3M1 drives the Rx turret round. The turret is ganged to a six
position rotary switch 3 s 1. Every alternate switch position is used,
six positions being included for mechanical design purposes only. A
single lobed cam on the turret opens and closes microswitch 352 in
sympathy with 3S1 breaking and making. 3S2 is included to ensure a
high degree of repeatability of turret positioning.
g. When the turret has rotated far enough such that 3S1 is in the Band I
position and 3S2 is made, relay 3RLA re-energises. Contact 3RLA-1
removes the OV input to the 2 input NAND gate thereby removing the
Tuning Inhibit. Contact 3RLA-2 removes the OV from motor 3M1 and
replaces it with +28V. With +28V connected to both sides, 3M1 stops
immediately and is not permitted to "run-on".
h. Contact 3RLA-I places OV on motor 4Ml (TX turret) via relay contact
4RLA- 1 (de-energised).
j. 4M1 rotates, taking with it rotary switch 4S1 and microswitch 4S2, in
the same manner as switches 3S1 and 3S2 were moved by the Rx turret.
Upon reaching Band 3 with 4 s 1 in the Band 3 position and 4S2 made,
relay 4RLA re-energses. Contact 4RLA-1 removes the OV from 4M1 and
replaces it with +-28V, thereby stopping it.
53. Incorrect Frequency Setting The construction of the FSS makes it
possible to select frequencies outside the frequency range of the set. These
are designated 'Prohibited Frequencies' and their selection results in OV
being applied to the Setting Incorrect line. This is fed as a logic 0 to the
other input of the 2 input NAND gate 3TR1 placing an inhibit on the synthesiser
tuning. Diode D2 is forward biassed placing OV on the select Band 1 line.
54. Thus both turrets tune to Bandl, but because of the tuning inhibit from
3TR1 the receiver synthesiser does not tune, resulting in the front panel
alarm being activate.
FREQUENCY CONTROL
55. The RT 353 may be tuned to any one of 1840 channels spaced 25 kHz apart
(narrow) or 920 channels spaced 50 kHz apart (wide). To obtain rapid channel
selection and to maintain the selected frequency to a high degree of accuracy
control loops based on a digital frequency synthesiser are employed.
56. A reference frequency at 4.84375 MHz from a temperature controlled
crystal oscillator is fed to a fixed divider in the synthesiser. This divider
provides two outputs one at 968.75 kHz, (divl5) and one at 78 1.25 Hz (did6 1OO),
the latter is fed to a frequency and phase comparator within the synthesiser.
57. A portion of the local oscillator frequency (fo) is fed to a variable
divider within the synthesiser whose division ratio is set according to the
particular frequency set on the frequency setting switch, the resulting
output at fo/N is fed as the second input to the frequency and phase comparator.
58. Any detected frequency error at the synthesiser comparator inputs results
in a logic output to the motor control circuits. This output consists of a
train of pulses at a p.r.f. corresponding to the size and sense of that error
(low/high). The control circuits cause the motor to drive the receiver main
tuning capacitor in the correct sense to remove the detected error by coarse
tuning the local oscillator, the transmitter oscillator being simultaneously
coarse tuned. This primary loop gves a fast pull-in facility to bring the
system rapidly within the capture range of a secondary Delta-Sigma loop in the
motor control circuits.
59. When the inputs to the comparator are within I cycle of one another, the
frequency highllow drive to the motor circuits is removed and replaced by a
local oscillator phase error signal routed to the Delta-Sigma loop circuits.
In this loop system the local oscillator phase error signal is first used to
inch the motor drive to within the capture range of the varactor diodes in
the local oscillator and, having attained this condition, the varactor diodes
then fine tune the local oscillator. The varactor diodes are held in the centre
of their operating characteristic by the inching action of the secondary loop.
60. Fine tuning of the transmitter oscillator is accomplished on a separate
sub-loop system where a portion of the local oscillator output is mixed with a
portion of the transmitter oscillator output to produce a 'Transmitter LF' of
9.6875 MHz. This transmitter IF is fed to a discriminator centred on 9.6875 MHz
with a bandwidth of approx 2 MHz whose output is applied via a summing amplifier
to the varactor diodes in the transmitter VCO to gwe a fast 'pull in' facility
to the oscillator. The transmitter IF is also fed as one input to a frequency
and phase error detector, the second input to the detector being the 968.75 kHz
output from the fixed divider in the synthesiser.
61. Any detected frequency error produces proportional d.c. correction voltage
fed to varactor diodes in the transmitter oscillator tuned circuit to cause the
frequency to change in the correct sense to remove the existing error. With
frequency errors removed, phase relationships are compared and the varactor diode
d.c. correction voltage is modified to remove any detected error.
62. Phase lock detector circuits monitor the phase error detector, and a
Tx Lock (=I) signal is produced by Modulator Board 2b dependent upon four
conditions. These are:
a. Presence of 9.6875 MHz transmitter IF.
b. Presence of 968.75 kHz reference frequency.
c. Presence of transmit 3 command.
d. No phase slip between a. and b.
63. Once tuning is completed the main loop system is continuously selfmonitoring to phase-lock the local oscillator to the reference frequency.
The transmitter fine tuning loop however is only operative when the transmit
command is present ( gpressel operated).
I
3.SV REF
T
Fig 7. Complete Control Diaaam RT353 Receiver
I
mQ
Dh62OO
TCXLO
I
1
VARIABLE
D-ER
mQ
SWITCH
Fig 8. Coarse Tuning of Receiver Local Oscillator
and all RF Tuned Circuits
-
1STLO
-
FREQUENCY
CONTROL
LOOP 2
I
VARACTOR
BUFFER
AMP
AMP
I
v
Ir
PHASE
Div62OO
TCXLO
I
REF
V
ERROR
484375 MHz
I
I
PHASE
COW
A
VARIABLE
+ DIVIDER
L
Fig 9. Fine Tuning of Receiver LO
19
Df 16
mQ
SEITING
SWITCH
FREQUENCY
CONTROL
LOOP 3
297 Hz
k
MOD
CONTROL
BUFFER
AMP
VARACTOR
AMP
Div 16
PHASE ERROR
B M P m
PHASE
484375 MHz
REF
V
ERROR V
L
TCXLO
Di.6200
PHASE
COMP
u u u
4
VARIABLE
DrVTDER
Fig 10. 'Inching' Action - Receiver LO
I
.
v
FREQ
SEITING
MODULATOR
INWT
--
4
4
A
SUMMING
&I
SLOW LOOP
FAST LOOP
Fs
Tx VCO
a
CONTROL
IFMMER
FAST LOOP
DISC
9.6875 MHz
I
9.6875 MfIz
m-
4
FILTER
-.
Rr LO
Fs + 9.6875 hfHz
FREQ AND
PHASE COhIP
I
Fig 1 1. Tx AFC Block Diagram
-
a
I
Div 320
8
jr
FREQUENCY CONTROL VOLTAGE
I
TX OSC
L 1
m
Fig 12. Frequencv Control Block Diagram
RECEIVER
RF Amplifier
64. The received r.f. signal which also contains the 150 Hz Clansman
recognition tone when NARROW or WlDE TONE modes are selected, is routed from
the front panel AETITUKF socket vla the antenna change-over relay (de-energsed)
to the selected turret lid r.f. This turret lid contains a high selectivity
double tuned r.f. tuned circuit. The output of the turret lid r.f is fed to
the grid of triode VI , which with transistor TRl in cascode forms the first
r.f. amplifier. This configuration is used because of its high gain, low
noise characteristic, & it introduces the gain of a pentode without its
inherent noise.
Fig 13. V1 with TR1 in cascode
65. The cathode of Vl is taken to the Front End Protection Unit, which provides
a cathode current of LL 9mA, UL 1lmA for normal signal operation. Under large
signal conditions, the consequent increase in V2 cathode current is drawn from
the bias control circuit up to a maximum of 5rnA. Current drawn from this source
results in the cathode voltage increasing in the range +7V to + 38V, which
reduces the gain of V1 proportionally. A bias voltage in the range -30V to + l V
is also produced and applied to the anode of a PIN diode which is connected
between the signal input line to V1 grid and the OV line. Reception of an
extremely high signal will cause the cathode voltage to exceed 37.9V, at which
point the bias voltage to the PIN diode, having increasing from -30V has
become positive, thereby forward biassing the diode, causing it to conduct and
shunt the received signal to OV. V1 and the subsequent stages are thus protected.
F ~ 14.
P Front End Protection
66. The amplified output of VlITRl is fed to the selected turret lid bandpass
which contains a high selectivity triple tuned r.f. tuned circuit and local
oscillator tuned circuit. The total selectivity provided by the tuned circuits
in the turret lids (r.f. + bandpass) is such that receipt of a signal whose
frequency is more than +I-5% away from the frequency of the wanted signal is
greater than 15 dB down on that signal. The output of the turret lid bandpass
is fed to the grid of V2, a conventional triode r.f. amplifier. V2 output is
fed as one input to the signal mixer.
67. Local Oscillator The local oscillator is a VHF Colpitts oscillator
operating in the range 40 to 86 MHz, controlled by the frequency synthesis
loop. The local oscillator output is fed to a buffer amplifier which matches
the single input to three outputs. One output is used as the second input to
the signal mixer, and the other two are used in the frequency synthesis loop.
The local oscillator output is modulated by the 85 Hz tone generator on Control
Board 2c for squelch operation. This tone is inhibited when the transmit (=I)
is produced by control board 2c or when data working is selected (except when
clear speech is commanded).
68. Simal Mixer The signal mixer is a balanced WE mixer converting the two
inputs (from the turret lid bandpass and the local oscillator) to a push pull
output at the difference frequency of 9.6875 MHz. This frequency is fed to the
Signal IF Output which is a balanced transformer tuned to a centre frequency
of 9.6875 MHz.
IF-Unit
69. The frequency modulated first IF at 9.6675 MHz is passed via relay contacts
to one of two crystal filters, one for WIDE band (50 kHz channel spacing) and
one for NARROW band (25 H z channel spacing). The selectivity produced by these
filters is such that frequencies outside the filter pass bands are greater than
80 dB down on the wanted signals.
70. Relay contacts select the appropriate filter output and pass it to an AGC
controlled IF amplifier with a gain of greater than 100 dB. AGC is employed to
prevent overloading the stage and prevent 'pulling' of the local oscillator
frequency. The AGC voltage is also passed to the front panel test meter to
give an arbitrary indication of the received signal strength. This meter
indication also provides a useful aid to fault finding
71. The amplified IF output is fed to a balanced mixer stage where it is mixed
with the output of a crystal controlled oscillator at 9.575 Mz to produce a
second IF of 5 12.5 kHz. The second IF is then limited before being applied to
a Round Travis type discriminator tuned to 3 12.5 kHz. The resulting demodulated
output is passed via a buffer amplifier to the Audio Board 2d and the Control Board 2c.
72. For data working the IF output is routed to HARNESS Plug pin D via the
MODE switch S2 for onward routing to the data equipment.
Audio/Tone Circuits
73. The demodulated output taken to control board 2c contains:
CONTROL BOARD
SQUELCH TONE @5&)
I
Fig 15. Squelch Tone Circuits
a. the 85 Hz squelch tone (except for data selections of MODE switch S2
when clear speech is not commanded).
b. the 150 Hz Clansman identification tone (except for WIDE and data
selections of MODE switch S2 when clear speech is not commanded).
74. The input to Control Board 2c is passed through a h g h 'Q' active filter
nominally tuned to 85 Hz but which will pass 150 Hz. The filter output is
routed to both the squelch and tone detector circuits.
Squelch System (85 H z )
75. The 85 Hz tone is generated by a three stage RC oscillator whose output
is fed via a series regulator circuit to the first local oscillator. The 85 Hz
oscillator is inhibited in the transmit condition and in data mode working.
76. The squelch tone on the demodulated signal is fed to the squelch detector
which produces a squelch detected (=0) output. The squelch detected (=O) signal
is fed:
a. to logic circuits on the audio board 2d to open the squelch gate.
b. to the modulator board 2b for data working
c, to the MODE switch S2 for auto working
77. The response of the first local oscillator for a given modulation level
input is not linear with frequency. Therefore, if the output level of the 85 Hz
tone generator were maintained at a constant level, the deviation produced at
the local oscillator would vary from channel to channel throughout the frequency
range. The output of the 85 Hz generator is therefore routed via a series
regulator, the output level of which is controlled by the level of the 85 Hz
on the demodulated signal, to maintain a constant deviation at the local
oscillator of 1 kHz throughout the frequency range. Resistor R80 is included
to reduce the output level of the 85 Hz tone generation when NARROW mode is
selected.
Tone Detection ( 150 Hz)
78. The 150 Hz content of the high 'Q' filter output is fed to a full wave
tone detector tuned to 150 Hz. The detector will respond to frequencies in
the range 146 to 154 Hz. Detection of the 150 Hz tone switches on a transistor
switch to g v e a tone detected (=0) output. In WIDE TONE and NARROW modes this
logic 0 is fed back to the transistor switch to maintain it in the on condition.
A transmit 3 (=I) signal switches on a second transistor switch which in turn
switches on the transistor switch controlling the tone detected (=0) output, which
is fed to the modulator board 2b together with the squelch detected (=O) output
for data working.
79. The 85 Hz tone is always used to operate the squelch circuit, and the
150 Hz tone, when present, is always used for automatic rebroadcast working.
When the set is in the WIDE mode there is no 150 Hz on the demodulated signal,
therefore to permit automatic rebroadcast the 85 Hz squelch tone is utilised to
simulate the tone detected (=O) output from the 150 Hz tone detector. The tone
detected (=O) output is also routed to the remote current detectors for auto working.
Audio Routing to Phones
80. The demodulated output from the IF buffer amplifier is passed through, a
150 Hz band stop filter before dividing into two paths:
a. the received audio path.
b. the sidetone path.
The received audio enters the unity gain amplifier ML3b (see technical notes
para 44) the signal path of which is controlled by the squelch detected (=O)
output from the 85 Hz tone detector, the alarm flash generator, TEST Switch
S4 and the transmit 1 line. With the alarm flash generator in the quiescent
(non-alarm) condition a logic 1 is placed on the 3 input NAND gate. 'Gate
Control 2' which together with the logic 0 from the squelch detector and
l o p 1 from the TEST switch S4 wafer CF (when not switched to OVERRIDE)
places a logic 1 on the negated inhibiting input of unity gain amplifier m 3 b .
The normal inhibiting input of h4L3b is connected to the transmit 1 line which
when the set is in the receive condition is at logic 0. ML3b is thus opened
allowing the received audio to pass through. After passing through a 300 Hz to
3 liHz audio filter (also shared by the transmitted audio path),the signal is
fed to unity gain amplifier ML,4a, whose normal inhibiting input is connected
to the transmit 1 line (logic 0 in receive condirion), and negated inhibiring
input is permanently connected to logic 1, and is thus opened, allowing the
s~gnalto pass through. The signal is amplified by the audio output amplifier
a d passed to the audio o u t p t transformer 2T I, and to the remote transfarmer
2T2 whenever reiay RIA is energised by the 'speak to remote' command fi-om
control board 2c. The output of transformer 2Tl is fed directly to the
HHmSS
plug pins D and E for all anelope setti~gsof MODE switch S2, and
to the AUDIO cormector via the gain control. The ouiptit of rznote rransfomer
2T2 is routed directly to the REMOTE terminals SK5 and SK6.
8 1. When in the transmit condition, due to the 85 Hz tone being inhibited,
the squelch gate ML3b cannot open. If it were opened the sidetone wiould mix
with the trmsmitted audiv in the 300 Ez 40 3k.H~ filter ca~singdistcrtion.
To ailow the sidetone through to the receiver phones, unity gain amplifier
ML4b is opened by the transmit 1 (=I) line thereby isolating the sidetone
from the transmitted audio
TRANSMITTER
MODULATTON ROLTTINCJ
82. In the analqye mode the *ir.rophone input is pre-amplified on assembly f ld) before being
applied to a gain control. This coztrol is meshar,isally linked to the receiver audio output gain
control such that increasiilg the microphone gain decreases the receiver audio gain and
vice-versa, preventing unwanted feedback and providing a whisper facility.
The gain control output is routed to a buffer amplifier on Audio Board 2d.
83 The harness/rernote microphone inputs are not subject to gain control and are routed
via remote transformer 2T2 and relay contacts on 2d before being applied to th~rebuffer amplifier.
84. The buffer amplifier output is routed to a constant voltage amplifier
(CVA) functioning as a peak noise limiter acting in an AMC circuit without
detracting from the modulating characteristics of the audio signal.
85. The CVA output is routed via 2d ML3a (open in transmit condition) to an
t
active audio filter which is shared with the received audio, the filter o u t p ~being
passed to Modulator Board 2b . 'The 15OHz identification tone is routed
from Tuning Board (2a) to Modulator Board (2b). For WIDE selections of
MODE switch laS2 the 150& tsne is inhibited.
86, In Data mode working the data input is fed directly to the h/Iodula:or Board
(2b) by-passing circuits so far mentioned. The 150IFlz tone is inhibited far
data working.
8'7. For Narrow selections of MODE switch (la)S2, the modulating inputs to (2b)
(analogue/dataltone) are routed via a 1 k ohm resistor to a summing amplifier to
provide the required 5k% deviztion. For WIDE selections, a second !k o h
resistor is switched in parallel to effectively double the current and hence
produce 10& deviation. The dc oscillator control voltage from the frequency
synthesis loop is added to the modulating signals in the summing amplifier to
produce a coxnposite output which is ro-uted to the Transmitter (4).
88. The trmsmitter oscillator has a separate voltage contitro!led oscillator
for each frequency band, located in the turret lids. Each osciilator is a
common emitter astable mdtivibrator giving an output of appro.ximately 50V
peak to peak The osci!!ztttors, pre-set by external capacitor C!, are tuned to
the selected frequency by the frequency synthesiser loop, varactsr diodes
being used for fine frequency control. The 28V supply to the osciiiators is
routed via transistor switches on Control Board 2c, contmEd bj;the
transmit 3 (= 1 j command. Modulatim is achieved by rsuxing the. sizamming
amplikr output via a varactur amplifier to varactos diodes which h r m pas uf
the voitage conirrola'ed o ~ ~ ~ ~ ~ a i o r s .
-17
a 'Tx lock (= 1 ) - transniitter frequency sqnthesrser loop locked
b. AXFAT temp (= 1) - no overheat of AWAT
c. Temp (=1) - transmitter temp within Limits
d. Synth lock ( = l ) - frequency synthesis loop coarse tuning complete
90. Tf one or more of the above inputs changes to logic 0 (fault) the PA On
(=I) command is not pm$:ced, thus &hibiting the transmitter. Ccnditims b
and c may be overridden by settmg TES'I' switch S-i to OVEiiliii>E, should an
emergency occur and the transmitter must be used.
9 1. The PA On condition can be stated most concisely by using the BOOLEAN
EQUATION:
PA Or! = Syr!th lock. Tx lock (?'emp.AJWAT T e z p + OR)
ie FA os = Synth lock AND Tx lock MYE~
Temp AP.D M A T Temp
PA On = Synfn lock AND Tx lock A h 3 01%
92 The PA On (=I j is applied as one input to a two input NANT, gate, the
other input being from a 30 sec delay circuit 30 sec after switching on the
equipment, the delay circuit provides a3 output (=I). Ths is a safety device
io allow sufficimt i;vzriii iip tiii-ie fix the FA 'vtiith boih iii-pis present the NAND
gate activates the lamp and relay drive circuits and enables the bms control
circuits.
P O W R AMPLIFIER
93. The Power h p i i i j e r consists of a power tetrode output vaive. T'ne PA
cathode current flows through a combination of resistors on Control Board (4d)
selected by the POWER switch S5 The effective resistance for each switch
settizg is as fcllows:
94. A ccnsta~tvo!tage !cop acts to ixai~ltainthe PA cathcde pelentml at 3. IV
wrt ijTVTby acijuting the grid bias within the range -20'1; to -260V as the caihodt:
current IS adjusted by POWER switch selection The power delivered by the PA
is directly proportional to its cathode current: thus the POWER switch controls
the rf powe: ~ u t p ~The
f . Tx c!p position of TEST switch S4 gives ax indicatim
ofcathode potentiai. As the cathode po~entlaiis maintained ar 3. iV, the
front panel test meter will indicate centre scale on all four ranges for
correct power outputs.
Should the antenna become open or shod circsit, the constant voltage loop
biasses the power amplifier hard back to protect it and its associated circuitry.
CONSTANT
VOLTAGE LOOP
Fig 16. PA Bias
95. The power output is fed to a harmonic filter located on the end plate
assembly (4e), there being one filter per band. Each filter passes frequencies
in the selected band with an attenuation of less than @.5dB,whilst for
harmonics of these frequencies the attenuation is greater than 30dB.
PA OUTPUT
96. The output of the selected harmonic filter is routed via the antenna
change over relay contacts to the ANTITURF connector on the fi-ont paiel.
97. True sidetone is achieved by leakage across the contacts of the antenna
c.hange over relay into the receiver circuits. The sidelong path on Audio
Board 2d is via unity gain amplifier ML4b to the audio output amplifier,
by-passing the squelch unity gain amplifier ML3b.
TRANSMIT COMMANDS
98. Presence of either pressel 1 (= 0) or pressel 2 (= 0) command from the front
panel audio sockets will produce a transmit (= 1) command from Control Board 2c
when REMOTE switch (S6) is set to LOCAL. A current of 8-1 1mA drawn from either
the harness microphone lines or the remote terminals produces the same transmit
(= 1) command for E M or AUTO selections. This transmit (= 1) command is also
used to inhibit the 85- squelch tone.
99. The transmit (= 1) output from Control Board 2c is fed:
a. to Audio Board 2d:
(1) to enable the Tx af unity gain amplifier ML3a and the sidetone
unity gain amplifier ML4b.
(2) to inhibit the squelch unity gain amplifier ML3b, and the Rx af
unity gain amplifier ML4a.
b. to Tuner Control Board (lj) (designated transmit 2)
100. Provided the TUAMTN402 is not tuning, the transmit 2 command is routed
via relay contacts on Control Board (Ij) to:
a. Modulator Board 2b to enable the transmitter frequency synthesis
fine tuning loop.
b. Control Board 2c for control of the tone detector circuits.
c. The Transmitter Unit (4) to enable the transmitter oscillator.
101. The transmit 2 command is inhibited in the FANS OFF position of TEST
switch S4 to prevent transmission under radio silence conditions.
102. During SILENT TUNE of the TUAAMKN402, OV is fed to the Audio Board 2d
(along the transmit 2 line) to inhibit the Tx at unity gain amplifier ML?a,
thus ensuring that the high power rf output into the TUAAMiTN402 is not
modulated under radio silence conditions.
103. For data selections of MODE switch S2 the transmit command originates
from the data equipment and perfonns the same functions as already described
for the transmit 2 command. The audio routine is held permanently in the
receive condition as the data input by-passes the Audio Board.
REMOTE SWITCH CONTROL FUNCTIONS
104. For analogue selections of MODE switch S2, Control Board 2c produces control logic
outputs according to the settings of REMOTE switch S6.
105. Local For LOCAL, setting of the REMOTE switch it is required that full control of the
equipment is with the local operator only. The 'speech to remote' relay 2dRLA is energised
allowing a remote operator to monitor traffic. The remote transformer 2T2 output is
connected to the HARNESS plug via the MODE switch S2 allowing any harness
operator to monitor traffic. Depressing either the harness or remote pressels produces no
change in the logic outputs from Controf Board 2c, and control of the equipment
remains solely with the local operator.
106. Remote For REM selection of the REMOTE switch it is required that both
local and remotelharness operators shall have control of the equipment.
Depressing either local pressel puts the equipment to transmit without deenergising relay 2dRLA, thereby maintaining the remote monitor facility.
Depressing either the harness or remote pressels draws a current of 8-1 1rnA via
the remote transformer 2T2 through the current detector. This results in a
send command from Control Board 2c logic circuits, putting the equipment to
transmit. Relay 2dRLA is de-enerpsed allowing the audio from the harness1
remote microphone to be fed to the modulator via the remote transformer 2T2,
contact 2dRLA-1 (de-energised), the CVA, unity gain amplifier ML3a and the 300Hz
to 3kJdz filter. Control of the equipment is now with the harnesslremote
operator as well as the local operator.(The local operator, however, has priority)
107. Auto For AUTO selection of the REMOTE switch it is required that the
equipment forms part of an automatic rebroadcast link. In this role it must
fulfil two functions:
a. To receive a signal via the antenna and to pass the resulting audio
to modulate another equipment connected to the harness pluglremote
terminals, and to put that equipment in the transmit condition so that the signal is rebroadcast.
b. To receive audio via the harnesslremote lines and route that audio to modulate the
transmitter, and to rebroadcast the information in answer to a send command received
from the harnesslremote lines .
Setting S6 to AUTO places the set on receive, energises relay 2dRLA, and selects the current
detector on Control Board 2c. Reception of a signal containing the 150Hz identification tone
in WlDE TONE or NARROW selections of MODE switch 52, or detection of the 85Hz squelch
tone in WIDE selections introduces the 10mA load on Control Board 2c. This load is connected
via remote transformer 2T2 and the remote terminalsharness plug to the current detector of the
set connected to the remotelharness terminals. The 8- 1 IrnA drawn fi-om that current detector
puts the remotehamess equipment in the transmit condition.
108. Relay 2dRLA routes the received audio to the equipment connected to the remote
terminalslharness plug via remote transformer 2T2. With the link working in the reverse
direction the roles of the local set and the remote set are reversed. Each operator can
monitor the traffic through the auto-rebro link.
Fig 17. Auto Rebro Link
109. Break In For BK-IN selection of the REMOTE switch it is required that
the local operator acts in a supervisory capacity during automatic rebroadcast
working. To achieve t h s he must perform three functions:
a. Inhibit the rebroadcast link
b. Receive from both ends of the link
c. Transmit to both ends of the link.
110. Setting S6 to BK-IN places the set on receive, de-energises relay 2dRLA, introduces the
current detector on Control Board 2c and places a BK-IN logic command (= 0) on to audio
board 2d. Relay 2dRLA being de-energised prevents any audio being routed to the remote
pluglharness terminals, and the tonelsquelch detected (= 0) does not connect the IOmA load
in Control Board 2c resulting in no current being drawn from the remotelhamess current detectors.
The auto-rebro link is thus inhibited in one direction. Upon receipt of a send command from the
remoteharness 1OmA load, Control Board 2c does not produce a logic command to put the local
set to transmit, thus the auto-rebro link is inhibited in the reverse direction.
I I I . The local operator is able to monitor his own received signals by normal
receiver act~on.Tomonitor signals from the remote set the BK-IN logic
command (= 0) to the Audio Board 2d is used to open unity gain amplifier ML3a,
the Tx af gate. ML3a is normally closed in the receive condition, but the
signal from the harness plughemote lines is now routed via ML3a7ML4a and the
audio output amplifier to the local phones. Depressing either local pressel
produces logic send command from Control Board 2c, placing the local set to
transmit. The I OrnA load on Control Board 2c is also switched in and relay 2dRLA
is energised putting the remote set to transmit and routing the transmitted
audio to it.
112. Intercommunication (IC) For IC selection of REMOTE switch S6 it is
required that the local operator shall be able to communicate with the harness1
remote operator without rf transmission.
113. Setting S6 to IC places the set on receive, de-energises relay 2dRLA,
connects the current detector on Control Board 2c and places an intercom logic
command (= 0) on Audio Board 2d.
114. The intercom logic command (= 0) to Audio Board 2d opens mity gain
amplifier ML3a in the same manner as did the BK-IN logic command.
The local operator can now hear the remote operator via the remote transformer
2T2,2dRLA (de-energised), ML3a, ML4a and the audio output amplifier. Any
audio from a received rf signal at the antenna will also be heard by the local
operator when switched to IC.
115. Depressing either local pressel energises relay 2dRLA without putting the
set to transmit. Audio from the local operator is now fed via ML3a7NIL4a,
audio output amplifier, relay contact 2dRLA-1 (energised), and remote transformer
2T2 to the remotelharness phones.
116. Call For CALL selection of the REMOTE switch it is required that the
local operator shall be able to gain the attention of the remotelharness operator
by producing an audible tone in the remotelharness headset. Similarly the
remotelharness operator must be able to call the local operator.
117. Setting S6 to CALL places the set on receive, energises relay 2dRLA, and
connects the current detector on Control Board 2c. Wafer AJ! of switch S6 draws
more than 15mA from the current detector circuit which produces a call (= 0) to
the control logic circuits and to Tuning Board 2a, where it is inverted to
enable a 2-input NAND gate. The 2kHz call tone is derived from the temperature
controlled crystal oscillator after which it is divided down and fed as the
other input to the 2-input NAND gate. After passing through the NAND gate the
call tone is fed to the audio output amplifier from where it is routed to the
harnesslremote phones via relay contact 2dRL-I (energised) and the remote
transformer 2T2, In all positions of S6 except CALL, if the remotefharness
operator depresses his CALL switch, he places a load of 10 ohms or less across
the remote terminals/harness plug, thereby drawing a current of more than 15mA
from the current detector on Control Board 2c. The call is then generated in
the same manner as for local operation of switch S6.
TEMPE3ATLJRESENSOR (4k)
118. The control input to the series limiter in the blower supply line is
produced by a temperature sender located in the transmitter. A positive
temperature coefficient (PTC) resistor (THI) located in the transmitter heat
transfer wall is used to control the bias of a transistor amplifier such that
for temperatures of below 60 C the blowers are inhibited, and for temperatures
above 70 C they are switched on. The control output is routed to the series
limiter in all but FANS OFF and OVERRLDE positions of TEST switch S4. In the
FANS OFF position the blowers are permanently inhibited, and in the OVERRTDE
position switch S4 provides a OV input to turn the motors on.
119. A second PTC resistor (TH2) is also located in the transmitter heat transfer
wall. For temperatures above 95 C TH2 inhibits the transmitter by routing OV
to the alarm flash circuit. In this condition, with TEST switch S4 set to
TEMP the front panel test meter (laME1) will read 'hard left' in the red sector.
The transmitter inhibit may be overridden in emergencies by setting S4 to OVERRIDE.
CONTROL OF WAAMiTN402
120. Information passed by the set to the TUAAM/TN402 via the front panel TURF
connector (laSK3) is:
a. +28V d.c, at pin 3 (except for OFF and TUNE positions of POWER switch S3).
b. OV at pinP.
c. Silent tune (OV) at pin 0 (when POWER switch S3 is set to '0').
121. Information received by the set from the TUAAMPTN402 via the front panel
TURF connector (1aSK3) is:
a. Tuner key line (OV) at pin M (during TUAAM/TN402 tune sequence).
b. ARFAT temp (-1) at pin L.
122. Setting the POWER switch S3 to the spring loaded TUNE position breaks the
28V supply at pin S of the TURF connector and starts the tune sequence. After
breaking this 28V supply to the tuner, it's re-connection by returning S3 to
any position except OFF, produces a OV on the tuner keyline (pin M) whch is
fed to the tuner control board (lj) energising relay IjRLl. Relay contact
RL1-2 places a permanent logic 1 (=transmit) on the transmit 3 line, and
contact RL1-1 bypasses the POWER swith S3 and places OV directly on to the
power 4 line. Contact RL1-2 thus puts the set to transmit, and contact RL1-1
switches the PA to power 4 (50W nominal output).
123. In the '0'posistion of POWER switch S3, OV is placed on the silent tune
line (pin 0) which switches in a dummy load in the TUAAMlTK402, thus ensuring
that no r.f. power is irradiated from the antenna during the tune sequence when
radio silence is required.
124. When the tuning sequence is completed the OV is removed fiom the tuner
keyline (pin M) de-energising relay ljRLl and putting the set back to receive.
125. Normal transmit will be inhibited as long as POWER switch S3 remains in
the '0' (silent tune) position.
126. Should the 50 ohms 10 dB attenuator in the ARFAT become too hot ciming
the tuning sequence the logic 1 at TURF connector laSK3 pin L changes to
logic 0, inhibiting the transmitter. In this condition, with TEST switch set to
TURF, the front panel test meter (1aMEl) will read 'hard left' in the red
sector. The transmitter inhibit may be overridden in emergencies by setting
S4 to OVERRIDE.
Fig 18. Power Supply Unit Block Diagram
127. The power supply unit is fundamentally a DC to DC converter controlled
by a square wave switching regulator. Control loops operate on the regulator
and converter to ensure adequate overload and over-voltage protection.
128. The voltage supply to the equipment, +24V nominaly is applied at (1a)PLI
from where it is passed via supply filter (le) to Meter Control Board (lb).
The negat~veline is also routed d1rectIy to (7g)X2 and the positive line to (1a)RLAl.
129. The Meter Control Board (lb) has a resistive network incorporating variable
con~ponent(1b)R I which enables the front panel test meter (1a)ME 1 to be centred
when the input voltage is at +24V d.c. (TEST switch 54 to 28V supp1:i).
130. The positive line conrtect~oninto (lb) is routed via (1b)Dl to Power
Relay RLA. In the event of a reverse polarity supply connection into (lb), D l
prevents (1a)RLA from energising. The negative supply to ( 1a)RLA is routed
via (1a)THT (closed for temperatures LT 85 C) and wafer AF of POWER Switch
53. (1a)RLA will energise for correct polarity supplies in the range 2 l-33V d.c.
at all temperatures below 85 C when S3 is in any position except OFF. With
(1a)RLA energised, contact RLAl connects the positive polarity input line to
(7g)Xl. Both input lines are isolated from the chassis.
131. The wide range of input voltage levels over which the power supply unit
is expected to perform to specification presents different impedances at XI
and X2.To compensate for this an impedance correction network comprising R1 and
C5 is incorporated.
132, Voltage Control The negative polarity input at X2 is fed to a series
regulator switch (7TR1) which switches on and off at a nommal32 kHz,controlled
by the regulator drive (7TR2), one input of a four input NAND gate (ML6a), a
D-type bistable (ML2b) and a clock pulse generator used as the clock input to
ML2b. (7g)D2 provides reverse spike protection for (7)TRl when it is switching
rapidly. The output of the series regulator is sampled and fed via a SET VOLTS
variable resistor to a voltage comparator, the reference voltage input of which
is derived from zener diodes. With the series regulator open, the sampled
voltage to the comparator falls below that of the reference resulting in an
output from the comparator (=I) being fed to a one input of NAND gate (MLGb),
inverted and fed as the clear (=O) input to h4L2b. The resulting logic 1 at
ML2b (NOT Q) output is fed as one input to the four input NAND gate ML6,
whose output (=O) is fed to the regulator drive to close the series regulator
switch (7TR1). With 7TR1 closed, the sampled voltage output rises above that
of the reference input, thereby removing the clear input to ML2b. On the
next clock pulse input to ML2b the Q output changes to logic 0 and is fed to
ML6a. The resulting logic 1 from ML6a ia fed to the regulator drive opening
the series regulator, allowing the sampled voltage to fall and the cycle to
repeat itself. A tendency for the sampled voltage to fall acts via the loop
to increase the regulator ON time, and a tendency for the sampled voltage to
rise increases the regulator OFF time. The regulator is self starting upon
application of voltage at X1 and X2.
133. Over Volts If, due to a fault condition, the sampled voltage rises to 22.5V, an over-volt
detector circuit produces a logic output to ML6a and the resulting logic 1 output from ML6a
holds the series regulator off The time for which the logic 0 is applied to MLGa is integrated
in a trip time integrator, and should this be greater than 4 mS a pulse is applied to a thyristor
(SCR) which places a logic 0 output to Mi6a to hold the series regulator off. Once 'fired',
the thyristor can only be reset by switching off the input supply (POWER switch to OFF).
134. Over Current The maximum available current drawn from the power supply
unit is controlled by monitoring the output of a tunnel diode oscillator which
is in series with the main current path. A tunnel diode is used as it displays
a negative resistance over part of its operating characteristic. When the
device is operated over this portion of the curve it can be used to enable
an oscillator. The frequency of the oscillator is approximately 1 MHz, but
it will only oscillate when the current instantaneously exceeds the trip level
(16.5A approximately). This will normally occur at least once during each
32 uSec period due to switching transients. Hence the output in any one
clock period of 32 uSec, consisting of a number of 1 uSec wide pulses, is fed
into a counting circuit via an inverting gate ML3a. The counting circuit is
set to ignore this spurious pulse. The counting circuit (ML4, MLSa) is cleared
every 32 uSec by the clock pulse generator, and should ML3a provide more than
7 pulses in any one 32 uSec period the trip cycle is initiated.
135. When an overload current is drawn from the power supply supply unit:
a. The tunnel diode pulse generator feeds negative going pulses of
approximately 1 MHz to M U a , where they are inverted and fed to the did8
counting circuit ML4, ML5a.
b. h&Sa output is used as the clock input to a J-K bistable hE5b which
clocks through both logic I and logic 0 permanently at its inputs.
c. The not Q output of MLSb changes to logic 0, which is fed as one input
to the four input NAND gate ML6a to switch off the series regulating
switch 7TR1 for the remainder of the 32 uSec period.
d. The Q output of ML5b changes to logic 1 and is fed as one input
to a two input NAND gate MLSb, thus enabling the gate.
e. A series of pulses from the div/4 counter ML4 is fed as the other
input to ML3b. Under overload conditions, the prf of these pulses is
high enough (approximately 250 kHz) for them to be considered as a
permanent logic 1.
f. The resultant logic 0 output from ML3b triggers a recovery delay
circuit the output of which changes to logic 0 and climbs back up to
logic 1 after approximately10 uSec, thereby inhibiting the two input
NAND gate ML3c for this period of time. With ML3c inhibited, no
reset pulse from the clock pulse generator can reach the J-K bistable
MLSa, via ML3c, ML3d. Thus, should a fault condition occur within
10 uSec before a reset pulse, this pulse wiIl be ignored and the
bistable will not reset until the next pulse, (32 uSec later).This
circuit is incorporated to ensure that the protection circuit is not
reset too rapidly after a fault condition occurs.
g. Upon receipt of the clear (=0) pulse, the Q output of ML5b
returns to 0, inhibiting ML3b.
136. Should the fault conQtion be permanent, and not just a transient, ML3b
output is permanently held at logic 0 and the output of the recovery delay
circuit is never permitted to climb back up to logic 1, thereby permanently
inhibiting ML3c. The logic 0 at the not Q output of MLSb is fed to the trip
time integrator which then operates in the same manner as during the over
volts fault condition. Once again, should the thyristor be 'fired', it can
only be reset by switching off the input supply and switching it back on.
137. The stabilised 18V is fed to an inverter operating at 5.33 kHz,the
inverter frequency being derived from the clock pulse generator and the did6
circuit ML1. The inverter output is fed to a power transformer, rectified
and smoothed to provide the requisite voltages for the ra&o. Addtional
voltage stabilisation is provided for the synthesiser supply.
CONTROL OF EQUIPMENT I
NDATA MODE
138. For data selections of MODE switch S2, control of the transmit'receive
function of the equipment is performed by the data equipment connected at
HARNESS plug laPL2.
DATA RE$EPTlON
139. When receiving data:
a. the demodulated output from the IF Unit (5) is fed via the MODE
switch S2 to the HARNESS plug pin D, by-passing the receiver audio
circuits. Various inputs are combined on the Modulator Board 2b,
producing an output to the HARNESS plug pin E to control the data
equipment. These inputs are:
(1) Tone detected (= 0) from Control Board 2c
(2) Squelch detected (= 0) from Control Board 2c
(3) Signal strength from the mixer and AGC detector in the IF
Unit (5).
b. It is required that the 85Hz squelch tone is inhibited. This is
achieved by the MODE switch 52 feeding OV to the modulator board 2b
when set to either DATA selection thus enabling the control logic
circuits. As long as the transmit clear speech (= 1) command is not
received from the data equipment, Modulator Board 2b feeds a logic 0
to the Control Board 2c as the Inhibit Squelch command. If a
"Transmit Clear Speech" command is received from the data equipment,
the Inhibit Squelch command reverts to logic 1 and the squelch tone
is restored.
DATA TRANSMISSION
140. When transmitting data, the 'Tx data' command at the input to the HARNESS
plug laPL2 performs the same function as the transmit 2 command for analogue
selections. As the data input by-passes the audio board the transmit 1 function
is not required to control the audio routing and is therefore taken to OV for
both DATA selections of MODE switch S2.
141. The data input at HARNESS plug laPL2 is routed via MODE switch S2 to the
Modulator Board 2b, where it passes through the data level potentiometer and
the current doubler circuit to the summing amplifier for transmitter modulation.
The data mode (= 0) input to Modulator Board 2b is used to inhibit unity gain
amplifier ML3a thus preventing any audio from either front panel AUDIO socket
modulating the transmitter.
142. When transmitting data it is required that the 150Hz tone is inhibited.
This is achieved by the data mode (= 0) input to Modulator Board 2b
being passed to the logic gating circuits. Provided the transmit clear
speech (= 1) command is not received from the data equipment, the resulting
logic 0 (tone off) output from Modulator Board 2b inhibits the 150Hz tone. The
150Hz tone is also inhibited in the WIDE selection of MODE switch S2 by a wide
mode (= 0) input to the Modulator Board 2b.
143. Associated Literature
EMEK Tels H6 10 - 6 19 Clansman Radio UKNRC 353
EMER Tels L2 10 - 2 19 Clansman VHF Antenna Systems
144. A m y Code Number
61393
6 1388
61 172
User Handbook for Radio Station UKlVRC 353
User Handbook for VHF Antennae for Clansman
User Handbook for Clansman Radio Control Harness
User Handbook for Test Set Audio, Radio Audio Accessories
User Handbook for Adaptor, Telegraph, Radio
INTRODUCTION
The Clansman Radio Control Harness is a system of active and passive electronic units,
connectors and ancillary audio gear designed to interconnect crew positions with the
installed radios in vehicle installations.
The Radio Control Harness can be fitted to provide for one, two or three radio
installation, depending on the operational role of the vehicle.
CLIMATIC DURABILITY CHARACTERISTICS
Clansman Radio Control Harness has been produced to meet all the requirements of
Class L3 of DBF 133 and is thus classified as Ground Equipment (exposed and immersible
unpacked).
It is capable of continuous operation between ambient temperatures of -40 C to +52 C
(plus solar radiation to give a case temperature of +75 C) under conditions of
heavy driving ram, salt spray, driving dust and sand.
It is also capable of operation in 95 - 100% humidity with temperatures not
normally exceeding 30 C.
The equipment will withstand rough treatment, including operational shocks when
installed m vehicles travelling over rough ground, and in armowed vehicles due
to impact of non-penetrating shells on the vehicles' armour.
The equipment will withstand immersion in up to 5 ft of water for at least two
hours and is immune to corrosion from acids and alkalies.
Operation is unaffected by severe comamination by fuel oils, hydraulic and
lubricating fluids.
Storage can be for long periods of tropical conditions in a trade pack.
Normal storage should be held within the range of -40 C to +60 C.
Normal vehicle supply (& nominal 28V) is used to power the Clansman Radio
Control Harness, and it will withstand variations in supply of 21V to 33V with
switching surges and pulses without malfunction. It is electromagneticallycompatible
with vehicular equipment.
LOGISTICS
The Clansman Radio Control Harness is a flexible system of eight control units and twelve
ancillary items. Flexibility is ensured by mechanical and electrical interfaces between
harness ring units, radios and audio gear. Faulty units areeasily changed and
diagnosed drtwn to sub-assemblies level.
A minimum range of sub-assemblies needs to be carried as spares.
It is possible to operate the equipment efficiently after only a brief period of ins-truction
and as such can used by relatively unskilled operators.
It is capable of efficient operation under difficult conditions, g in the dark or in a
vehicle moving across open country whilst subject to high ambient nolse,
(avehicle and gun noise, etc).
145. IC: Normal voice intercommunication between crew posistions with 'press to talk' facilities
LIVE IC: Voice mtercommunication between crew posistions with 'hands free' operation.
COMMUNAL IC: Common voice intercommunication between vehicles via communal
terminal and line
REBROADCAST: (LRB or RRB) Signals received by one radio are re-transmitted by the other.
This can occur through the harness using two installed radios (LRB) or one installed radlo
and a remote radio though a 1ine (RRB).
OVERRlDE (O/R): The O R allows any crew member's voice to be heard by all the crew,
in their right ear, irrespective of their switch settings without interferring with their selected
working channel.
WORKTNG SIGNAL: Signal of selected working radio or channel, heard in the left ear.
MONITOR (M): This allows reception of signals on a selected channel without
the ability to transmit, heard in the right ear.
REMOTE: (REM) To perform the same function as a person able to "use" the harness,
from a remote point. Operation of a radio or intercommunication via a telephone cable (D 10)
up to 3 km in length, or up to 5km using CTlO cable.
SYSTEMS
146. The basic harness configuration is the two radio installalion which can provide set
selection, IC, Live IC, Monitor and Ovemde facilities for all crew posistions.
The harness facilities, as determined by the B 2 , are also available to a Remote user.
Provision is made for Automatic or Manual rebroadcast between the two local installed
radios or between either installed radio and a remote radio.
The system will also accept a Central Warning Indicator (CWI) tone.
A three-radio installation would normally be used in a Command Vehicle role where
re-broadcast and remote facilities are not required. It provides the control of up to three radios,
normal and live IC, override and monitor. Communal IC is provided so that two or more vehicle
harnesses can be linked together for voice intercommunication whilst the vehicles are stationary.
UNITS FOR TWO RADIO SYSTEM
147. There is a combination of seven types of units which can be used in the two-radio system,
the types and quantities in any particular installation being dependant on the opperational
role of the vehicle.
Auto Manual - Local Remote rebroadcast facilities on two radios either in Local in Harness
or with one remote and connected via twin cable (D10) up to 3 km distance through the
remote terminals of the lR2.
148. Interconnectin Box 2 Radio (032,)
The 1B2 is used in a two-set installation and is a combined control, junction and power supply
unit for harness items. It contains an IC amplifier and acts as the inlet and outlet to the main
harness distribution for radios and remote users.
It enables the two installed radios, or one installed radio and a remote radio, to be connected
for manual or auto rebroadcast, as appropriate; or a remote user to be connected into the
harness to use an installed radio or talk to the crew using IC. These facilities are controlled
by a local operator whose headset is plugged into the 1B2.
From the vehicle supply 28V DC I S fed mtn !he box and nut to the harness items
The harness is protected by a I A fuse In the 1B2. The LB2 does not supply power to the
radios, loudspeaker amplifier or emergency crew control boxes.
For PRC-3511352 and LARKSPUR radios, the MAMJALIAUTO switch may be
lef't at AUTO for any condition of use from the harness
149. Interconnectinn Box 2 Radio, Crew and Remote (IB2CR)
As an alternative to the IB2 where rebroadcast is not required, the IB2CR may be used.
Its main advantage over more conventional alternatives is cost reduction since only one
box is required and it allows a virtually universal application.
150. Crew Box 2 Set (CB2)
The CB2 is the standard Crew Box. It gives the crew member access through the harness to
either of the two radios, one as a working set and simultaneously to the other for
monitoring purposes.
Volume controls are provided for both the working set and the monitor set
NORMAL, LIVE IC and LIVE IC + MONITOR posistions are providcd on the
selector switch. With LTVE TC selected the microphone is live all the time without the use
of a pressel, thus giving hands free operation on intercom.
Operation of the pressel under these conditions switches the selected working radio
to transmit With LIVE IC -t MONITOR selected with 'A' radio being worked and 'B' radio
being monitored, the hands free operation on IC is retained, the 'A' radio is heard in the left
ear and operation of the pressel causes the 'A' radio to transmit. 73' radio and IC are heard in
the right ear at a reduced level. Switching to OVERRIDE enables the operator to be heard
at all other crew posistions irrespective of their switch posistions.
151. Commander's Bax Fixed (CBF) and Commander's Personal Unit (CPW
The CBF comprises a fixed box installed in the vehicle and a CPU carried by the commander.
These boxes are always used together and are connected by a 2m or a lorn lead.
The CBF and CPU together provide all the facilities of the CB2, but the most imperative
controls, such as radio selection, press to talk and override are carried on the CPU which is
held by a webbing strap around the commander's neck. A standard CLANSMAN headset is used.
Webbing and headset cable are fitted with snatch release devices.
An independent pressel may be plugged into the CBF and it is in parallel with the press to talk
button on the CPU. When not in use, the IND PRESSEL switch should be OR,to prevent
accidental operation. The CBF will also accept tone signals from a Central Warning Indicator.
152. Driver's Box Fixed (DB) and Driver's Box Set Selector (DBS)
In installations where intercommunication facilities only are required, the DB is used by itself.
The DBS can only be used in conjunction with a DB; together they provide similar facilities as
the CB2. They are used in turreted vehicles where the DB is located in the driver's compartment
and the DBS in the turret. Interconnection between the two units needs only five wires through
the Rotary Base Junction (RBJ) and the DBS is controlled by an operator in the turret.
The DBS is fitted with an indicator lamp which lights when the selector is switched to I or Ia.
The driver has full intercom facilities as well as use of either radio, but he cannot work one
radio while monitoring the other. When a Tank Telephone is fitted, this can be connected
into the harness via the Driver's Box.
Fig 19. Interconnecting 80s-2 Radio (1B2 1
Fit 20. Crew Box 2 Set (CB2)
Fin 2 1 . Commanders Hos Fiscd (CRF)
Fiu 23. Drivers Box (DU)
1,JNTTS FOR THREE RADIO SYSTFM
153. Two additional units are used in a three radio system, they are the Interconnecting Box 3
Radio (IB3) and a Crew Box 3 Set (CB3). CB3 provides for the working of any of the three
installed radios while monitoring either of the others. IC and O/R are also available.
Any combination of CLANSMAN Harness Units, except the IB2, may be used in a three
radio installation. IB3 together with CB2 provide for the control of two of the three radios
by the CB2 operator as well as IC and O R . The IR3 is also fitted with Communal IC
terminals to allow intercom with the harness ring of another vehicle.
154. Interconnectinn Box 3 Set (033)
The IB3 is a junction and power supply unit for harness items in installations of up to three radios,
where rebroadcast facilities are not important. The IB3 connects the radios into the harness so that
(a) 'A', 'B' or 'C' radio, IC or CALL may be selected and operated from a C83 connected to
the HARNESS and ACTlC soc.kets on the lB3.
(b) Nornlal 'A' or 'B' radio, IC or CALL may be selected and operated from any CB2 connected
to the HARNESS socket on the IB3.
'A'
or 'C' radio, TC or CALL ('A', 'C', together with TC - ACTTC) may be selected and
(c)
operated from a CB2 connected to the ACTIC socket on the R33.
The operator will read C or B on the control box selector switch.
155. Crew Box 3 Set (CB3)
The CB3 is used in the special case of a three set installation and is used in conjunction
with the B 3 . It enables the user to select and operate one of the three installed CLANSMAN
radios, to select and monitor a second radio, and have intercoinmunication and call facilities.
ANCILLARY ITEMS
156. In addition to the standard range of boxes, there are ancillary units that can be supplied
to extend the range of facilities.
157. A n ~ l i f i e AF
r Loudspeaker (A AF L)
Amplifier AF Loudspeaker is a four watt audio amplifier which can be connected into the harness
ring and used to select and amplify a radio or 1C signal. It can drive up to four fixed (LSV) or
free standing (LFS) loudspeakers. The A AF L can be used outside of a harness installation,
completely seperate from the harness and be fed directly with signals from a radio or audio gear.
A 28V DC power source is supplied to the A AF L either from a battery or a vehicle power supply.
158. Loudspeaker Free Standing (LFS)
The Loudspeaker Free Standing is a portable loudspeaker fitted with its own volume control,
a short six-way connecting lead and a socket to which may be connected another loudspeaker
or a headset/handset to give talk-back facilities. Short distance remote use (up to 10m) is
available when the loudspeaker is connected via an Audio Extension Lead (AEL).
The loudspeaker may be connected to any audio socket in the harness for use under quiet
conditions, or it may be connected to any Amplifier AF Loudspeaker by up to 50m of
twin cable (DlO) or by AEL.
159. Loudspeaker Vehicle Mounting (LSV)
Loudspeaker Vehicle Mounting is an installed loudspeaker which can be connected into any
of the audio rocket.; i n the lian~css~mtallation9 r radio for u r e under quiet condificlns
or connected io any A AF L
160. Aud~oExtention Lead (AEL)
The audio extension lead provides short range (up to 10m) remote audio facilities from any
harness unit with an audio outlet It has access for two sets of headgear or handsets.
16 1. Rernote Combining Unit (RCU')
The remotc combining unit (RCU) permits one of the two CLANSMAN radios to he selected
and used on voice or lnorse as appropriate, and a second radio to be monitored; at a &stance
of up to 3 Kms over Dl 0 cable, or 5 E(ms over one pair in a CT 10 pr.
It contains a transistor amplifier to increase the signal power to the line and to provide a
locally-generated side-tone. The amplifier obtains its DC supply along the line from
the radio or harness.
When switched to CALL, a tone is generated within the connected radio, which is heard by
the local operator, and by any crew member switched to that radio.
The RCU is used as follows:
(1) To a two-radio installation:
(a) The line is connected to the B2.
(b) Morse and/or voice as appropriate are available on radio,
and IC and CALL within the harness.
(2) To any CLANSMAN radio (except PRC-320 and PRC-350); no harness
(a) The line is connected directly to the terminals on the radio.
(b) Morse andlor voice as appropriate are available on radio,
and TC and CALL within the harness.
(3) To PRC-320; no harness.
(a) The line is connected to the radio through the CRSLR.
(b) Morse andor voice as appropriate are available on radio,
and IC and CALL within the harness.
162 Remote Personal Unit (RPU)
The RPU permits the operation of CLANSMAN radios, CALL and IC with an operator at
the radio, at a distance of up to 3 Kms over Dl0 cable or 5 Krns over one pair in a CT 10 pr.
Cable is connected between the terminals on the unit and the REMOTE terminals on the radio,
or the LINE terminals on the If32 in an installation.
The unit is carried by a webbing around the neck of the user and the headset plugs into it.
Both webbing and headset cable are fitted w t h snatch release devlces.
The unit contains a transistor amplifier to increase the signal power to the line and to provide
a locally generated side-tone. The amplifier obtains its DC supply along the cable from the ra&o
or IB2. The unit is polarity conscious. A wrong connection will be indicated by the call tone
being heard at both local and remote terminals.
163. Interconnecting Box Harness Adaptor (IBHA)
The IBHA adapts the CLANSMAN manpack rado PRC-320 or PRC-35 1/352 for connection
into the harness system, and provides control and rebroadcast facilities through the harness, as if
the manpack radio was a vehicle radm The unit also contains an amplifier which raises the audio
output level of the rnanpack radio to that of a vehicle radio harness output.
The radio is powered from its own battery, which may be float charged from a DC charging unit.
The DC charging unit can obtain ~ t 28V
s supply thrntlgh the IRHA
PRC-320. The BHA is used in conjunction with the CRSLR of the PRC-320.
The CRSLR will be switched to E M . Normal selection and operation of the radio is available
from control boxes in the harness; manual, local or remote rebroadcast is possible through the IB2.
PRC-35 lI352. The normal selection and operation of the radio is available from control boxes
in the haness The radio will be switched to REM. Manual or auto, local or remote rebroadcast
is possible through the IB2. The radio will be switched to REM for manual rebroadcast and
to AUTO for auto rebroadcast as for any other VHF radio.
164. Set Combining Box (SCB)
The SCB is used when CLANSMAN radios are not in harness and 1C is not needed.
It enables an operator to use two radios, monitoring the receiver output of the radio not being
worked. A third radio may be held in readiness for selection, its cable being plugged into a
dummy socket on the box.
Connection to the radios is made using cables from the standard CLANSMAN range,
connected to the audio output of the radio. This cable length should not exceed 1 metre when
connecting the PRC-350 or PRC-35 11352. Any of the standard range of audio gear may be
connected, appropriate to the mode of signalling intended.
Audio levels, however, are adjusted at the radio.
165. Radio Adaptor Box (RAB)
The Radio Adaptor Box (RAB) enables the LARKSPUR generation of radios to be used
at their full potential when controlled from the CLANSMAN Radio Control Harness harness.
166. Interconnecting Box Radio Adaptor (IBRA)
The LBRA permits any installed CLANSMAN radio to be used by vehicle crew members
using LARKSPUR harness, headgear and remote control gear.
B R A converts a VRC into a C13142145 type radio, and a PKC into a B47148 type radio.
In the latter case, it is necessary to use an IB in the installation if the PRC plus B R A
combination is to be used as the 'A' set, since the I/C amplifier in the BRA is used to increase
the PRC audio output, and therefore is not available for IC use.
The type of radio input, VRC or PRC, is selected by a preset switch.
Power supply is fed through the box to the radios.
167. Kev Telegraph Manual (KTM)
The Key Telegraph Manual (KTM) can either be used free or clipped into a mounting tray
in its vehicle role. It is connected into any audio socket in the harness or radio by a short
jumper lead that is permanently plugged into one of its two sockets. A Clansman headset or
handset can be plugged into the second socket to monitor the key operation. In this mode,
normal audio facilities are available when the key is not being operated.
168. Remote Rebroadcast Box (RRB)
The Remote Rebroadcast Box (RRB) enables CLANSMAN HF radios to be used in the
rebroadcast function. This box may be used with IB2CR or IB3 in harness installations,
and SCB or RCU in non-harness installations.
SELF-PROPELLED
ARTILLERY
-
COhWUNTCL4T1ONHARNESS
169. An example of the application of this harness can be seen in the British version of the
Anglo-German-Italian SP70 self-propelled gun. In wminon with standard armoured fighting
vehicle practice the harness has a central feature of a harness ring with interconnecting boxes,
including as the main unit the Radio Lines Box (KLB).
Two features are included to meet the special requirements of self-propelled artillery:
(i) Automatic communication of gun laying data, in digital form, from the battery
command post over existing voice channels. This communication is effected by land line,
or in exceptional circumstances via the installed rado.
(ii) Two-way cordless communication with ammunition numbers working outside the vehicle
under non-silent conditions. This is achieved by use of rugged amplifierAoudspeaker units
mounted on the turret bustle. Either loudspeaker can be used as a microphone by the
operation. of a press-to-talk button. The use of two speakers ensures that at least one is
accessible at all turret positions.
A typical system includes seven types of installed box, of which the Interconnecting Box
Harness Adaptor (IBHA) and the Drivers Box (DB) are taken from the existing Clansman
range (the DB is utilised as a general crew box).
The personal communication gear, including the Commanders Personal Unit (CPU), is standard,
except that the CPU switch has a slightly different function from standard Clansman practice.
The radio equipment may be based on either a PRC-35 1 VHF Manpack adapted to the vehicle
role by use of the Interconnecting Box Harness Adaptor, or a Clansman vehicle radio, interfacing
directly with the RLB. Signals received over the radio or lines, or both, can be superimposed
on the harness intercommunication channel at the discretion of the commander.
170. Radio Lines Box (RLB)
The Radio Lines Box is operated by the commander in conjuction with his Commanders Personal
Unit (CPU). The controls comprise the working and monitor volume controls for his headphones,
the harness power supply odoff switch, the ordoff switch for the loudspeaker function of the AD3,
a live IC intercom switch for the commander's microphone, and a push button for passing a status
signal over the land line. The internal circuits include the lines signal amplifier, the crew
intercommunication amplifier, the voltage regulator for the harness power supply, and the relay
contacts by which signals, including the radio signals, are selected and diverted in response to the
CPU switch positions.
171. Amplifier Intercom Box ( A B )
Two identical Amplifier Intercom Boxes are mounted on the rear exterior of the turret bustle for
intercommunication with ammunition numbers working outside the vehicle. When switched on at
the RLB, both AIB's become loudspeakers, allowing the ammunition numbers to monitor the
harness intercommunication channel or be addressed by the commander. The volume of each ALB
can be adjusted independently by a control on the lower surface.
The operation of a push-button switch, located on the same surface of the AIB, connects the
loudspeaker into the harness as a microphone. A microphone amplifier is incorporated in each
AIB to raise the output of the loudspeaker to a level compatible with the output of the other crew
boxes. This facility is independent of the loudspeaker control switch on the RLB. Under silent
conditions a Clansman headset can be connected to the audio socket of either of the ATB's to
provide the user with the same facilities as the clew members inside the vehicle.
172 Loudspeaker Tee Box (ISTI
The Loudspeaker Tee Liox (LST) has two Sutlcilons
(I) As a harness junction box with two SPW outlets, one to each Amplifier Intercom Box (AU3)
(ii) As an interconnector between the two N13's so that operation of the press-to-tal k button
on either box mutes both loudspeakers, thus eliminating acoustic feedback
173. Interconnecting Box 12-way [IB12)
The Interconnecting Box 12-way (IB 12) is a junction box connection into the harness ring to
provide one spur outlet to the Emergency Crew Control equipment (ECC) and another,
via the slip-rings to boxes installed in the hull.
There are no operator controls on the box, and it has a wide field of potentla1 applications.
173. Telephone Adaptor Box. (TAB)
A tank telephone position, incorporating a handset, is mounted on the vehicle exterior.
This is also the normal connection point for line connection to the battery command post.
The Telephone Adaptor Box (TAB) is the first interior box to which the tank telephone
connects. The lines connection are linked through the TAB, and terminate at the Radio
Lines Box. The signals to and from the tank telephone handset are adjusted within the
TAB to levels compatible with the harness. The TAB also incorporates an indicator lamp
visible to the driver, who may respond to a call fiom the tank telephone handset by
operating a switch on the TAB, thereby, connecting the handset to the harness ring.
AUDIO ANCILJLARlES
174. Racal-Amplivox Communications Limited specializes in the field of electro-acoustics
and has developed the Arrnoured Vehicle Crewman's Helmet and Staff User's Headset
to meet the stringent requirements of the Clansman programme.
Both items incorporate the unique Amplivox "Acoustic Valve" in the earshells which can
be opened or closed at will. In the 'open' position, the wearer can hear important airborne
sounds such as commands, warnings, etc., whilst being protected fiom loud percussive
noises, such as gunfire. In the 'closed' position, the earshell becomes a high quality
ear-protector.
175. AFV Crewman's Helmet (Helmgard)
This helmet protects the AFV crewman against head injury due to the serious shocks
that can occur in an AFV when travelling at high speed over rough terrain.
Different head sizes can be accommodated by means of detachable headband comfort
pads and ad-justmentof the crown pad.
176. "A" Vehicle Staff User's Headset ( S o n o v a l v a
This maximum comfort headset has been designed for use by troops and other military
personnel engaged in areas of continuous or intermittent noise where headsets have to be
worn with seperately issued protective helmets.
This headgear is designed to be worn under the later style infantry helmet and will be used
by staff oficers in 'A' vehicles. It is fitted with noise-excluding earshells having adjustable
valves and a boom microphone, similar to those mounted in the AFV helmet.
177. "B"Y e h i ~ f f U s e r ' s I - l e a d s &
This headgear is sitnilx in gencsal design to ihe 'X x h i c l e staff'user's headgear>
but the earshells provide less noise exclusion and are not fitted with acoustic valves.
Primarily intended for use with the Clansinan range of Manpack and 'B' vehicle radio
sets, the assembly is fitted with rocking armature receiver insets mounted in foam
padded circum-aural earshells, a boom mounted noise-cancelling niicrophone and a
1 metre 6-way coiled cable terminated in a 7-way snatch connector, for connection
to the Pressel Switch Box Assembly.
The left-hand earshell carries the microphone boom and a 3-pole socket which provides
for the optional connection of the Clansrnan Respirator Microphone. The right-hand
earshell (Satellite) is detachable from the headgear, leaving its earpad in position to
stabilize the assembly. The action of attaching the Satellite to its earpad automatically
completes the electrical circuit to the right-hand receiver.
The headgear is compatible with the latest type of Infantry Helmet and also with Respirator,
Anti-Gas, No. S6. Cables atid earpads may be changed without the use of tools.
178. Pressel Switch Box Assembly
This assembly is for use with the Clansman Infantry and 'B' Vehicle Headgear,
AFV Creman's Helmet and the Staff User's Headset. It consists of a pressel box with
snatch socket, clothing clip and a coiled cable, extending to 1.5 metres, fitted with
a 7-way bayonet lock plug for connection to user equipment.
The fixed socket on the pressel box accepts the headgear while the main pressel bar
actuates a double-pole microswitch, controlling the microphone and sendlreceive control lines
The pressel box may be set to either the 'live microphone' or the 'switched microphone'
(Mic. Off-On) mode by adjusting the sliding stepped washer at the cord outlet end to the
appropriate limit of its travel and tightening the retaining screw.
179. Respirator Microphone
The respirator microphone is provided to allow communications to be retained when
wearing the AFV crewman's helmet or the staff user's headgear with the respirator S6.
The primary function is to maintain full voice communication facilities when the use of
a boom microphone is rendered ineffective due to the use of a gas rcspiratior.
It consists of a rocking armature receiver (used as a microphone) mounted in a rubber
housing designed to clip over the exit of the respirator voice valve. The cord of the
microphone terminates on a 4-way plug which iits into the respirator microphone socket
mounted on the associated assemblies. The fit of the microphone on the respirator is reletively
loose, and the cord is kept short, so that any snagging of the cord should displace the
microphone without breaking the seal between the respirator and the face.
180. Single Transducer Assemblv
The Single Transducer Assembly can be worn as a single-sided headset or used as a
hand-held microphone. The design includes a press-to-talk switch, webbing harness
and a coiled cable extending to 1 metre in length.
The single transducer assembly consists of a single rocking armature receiver,
which is used alternately as a receiver, with the pressel switch released, and a microphone
with the pressel switch operated.
1 8 I . General Purpose Handset
'i~'hcGcncral Purpose Handset may he used with any CI,RNSMAN sadio eithcr by
direct connection or through a control harness box. It is fitted with a rocking armature
receiver and a pressure gradient (PG) microphone. A pressel switch operates the
rado transmitlreceive or control harness IC switching.
The Remote Handset can be used to remotely operate the following radios, either
by direct connection over 3 Krns of Dl0 cable or through the control harness
via an IB2
PRC-320 via a CRSL/R, when not in harness.
(1)
PRC-35 11352
(ii)
VRC-353
(iii)
(1~)
UKPRC-344
The remote handset is fitted with a rocking armature receiver, a PG microphone and
a transistor ainplifie-r to increase the signal power to the line and to provide a locally
generated side-tone. A pressel switch operates the radio transmitlreceive or control
harness IC switching. A second pressel switch operates the call tone which is generated
by the radio, and is heard by the local and remote operators or all crew members
connected into a control harness. The handset is fitted with insulation piercing cable
contacts and is polarity concious. If it is incorrectly connected, a call tone will be heard
at both local and remote terminals.
183. Tank Telephone Handset
The Tank Telephone Handset is used in the tank telephone assembly mounted in an
armoured box on the outside of the vehicle. The handset is attached by 3 metres of
telephone cord which is wound on a spring loaded drum for automatic retraction after
use. The handset is similar to the GP handset but contains a transistor amplifier to
match into the vehicle harness circuits.
184. Associated Literature
User Handbook for CLANSMAN Radio Control Harness, Army Code No. 6 1172.
User Trials Report, School of Signals, Report No. 723 F/72.
Ease of Maintenance Assessment Report No. EME/8c/2896.
Technical Specifications, SRDE No. DS 1192B.
CREW BOX - 2 mTSTRtTC'TTON
Switch Positions
Working
Monitor
Facility
OFF
Work 'A' set; press to talk;
signal in both ears.
ON
Work 'A' set; press to talk;
signal in left ear.
Monitor 'B' set; signal in right ear
OFF
Work 'B' set; press to talk;
signal in both ears.
ON
Work 'B' set; press to talk;
signal in left ear.
Monitor 'A' set; signal in right ear.
OFF
Intercom; press to talk;
signal in both ears.
ON
Intercom; press to talk;
signal in left ear.
Monitor 'A' set; signal in right ear.
... ,
(Over-ride,
spring loaded)
Voice call without use of pressel;
heard by all crew members
Revert to I A for subsequent
communication.
An O R call from any other control box in
the harness replaces the signal in the CB-2
operators right ear, irrespective of any
switch settings. The loudness of the O/R call
will depend on the MOMTOR - VOL setting
ABorBA
Live TC
Microphone live - talk on 1C;
monitor IC in right ear.
Press to transmit on selected 'A' or
'B' set; signal in left ear.
ABorBA
+
Microphone live - talk on IC; monitor
'A' or 'B' set and IC in right ear.
Press to transmit on selected 'A' or
'B'
set; signal in left ear.
Switch Positions
Working
Monitor
A, B and C
OFF
Facility
Work selected 'A', 'B' or 'C' set;
press to talk; signal in both ears
Work selected 'A' ur 'B' set.
press to talk; signal in left ear.
Monitor 'C.' set; signal in right ear.
Work selected 73' or 'C' set.
press to talk; signal in left ear.
Monitor 'A' set; signal in right ear.
Work selected 'A' or 'C' set.
press to talk; signal in left ear.
Monitor 'B' set; signal in right ear
A, B and C
OFF
Lntercoinm; press to talk;
signal in both ears.
Intercornm; press to talk;
signal in left ear.
Monitor 'A', 'B' or 'C' set;
signal in right ear.
(Over-ride,
spring loaded)
Any
Combination
of
A, B and C
Call to all c.rew members
without use of pressel.
Microphone autornaticlly made live.
Revert lo I for subsequent commun~cation.
An O/R call hum any other control box in
the harness replaccs the signal in the CB-3
operators right ear, irrespective of any
switch sett~ngs.The loudness of the O R call
will depend on the MOMTOR - VOI, setting
Switch Positions
Monitor
Working
Facility
A
MORSE or
VOICE
Work 'A' set;
signal in both ears
AB
MORSE or
VOICE
Work 'A' set;
signal in left ear.
Monitor 'B' set;
signal in right ear.
BA
Work 'B' set;
signal in left ear.
MORSE or
VOICE
Monitor 'A' set;
signal in right ear.
B
Any
posistion
Work 'R' set;
signal in both ears.
MORSE or
VOICE
CALL
(spring loaded)
CALL tone heard by local operator
of selected working set, who will
switch to IC to reply.
Remote operator then switches to
VOICE for subsequent communication.
SET COMBNNG BOX INSTRUCTION
Switch Positions
Monitor
Working
Facility
VRC or
PCIC
OFF
Work selected set; press to talk;
signal in both ears.
VRC or
PCR
ON
Work selected set; press to talk;
signal in left ear.
Monitor other set;
signal in right ear.
signal in both ears
at reduced level.
LTVE TC
As 'A' or 'B'
-- NORM above
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