tl microwave radio order wire and alarm level and f

tl microwave radio order wire and alarm level and f
BELL SYSTEM PRACTICES
Plant Series
SECTION 409-31 0-502
Issue 1, August, 1962
AT&TCo Standard
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TL MICROWAVE RADIO
ORDER WIRE AND ALARM
LEVEL AND F-REQUENCY ADJUSTMENTS
The tests and adjustments listed in this section cover the order wire and alarm circuits at TL
radio stations as well as at the order-wire and alarm control station. All tests and adjustments
in this section can be performed without disrupting message transmission although the order
wire circuit is disabled during some of the tests. The tests should be made when no alarm
conditions exist on the system. No telephone headsets at any station should be plugged in during these tests unless specified.
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APPARATUS:
J99262AA Portable TL Test Set
KS-14510, List 1 Volt-ohm-milliammeter
262B Terminating Plug
STEP
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PROCEDURE
CONTROL PANEL FILAMENT VOLTAGE ADJUSTMENT
Note: Steps 1 through 5 need be performed only on initial installation or at such time
as adjustment is needed.
1
Set the KS-14510, List 1 volt-ohm-milliammeter to the 60-volt de scale.
2
Connect the positive voltmeter lead to pin 9 on the V1 tube socket and the negative
lead to pin 1 on the V1 tube socket.
3
Adjust the Vl FIL ADJ potentiometer until the meter indicates 40 volts.
4
With the KS-14510, List 1 volt-ohm-milliammeter still on the 60-volt de scale, connect
the positive lead from the meter to pin 4 on the V2 tube socket and the negative lead
to pin 3 on the V2 tube socket.
5
Adjust the V2 FIL ADJ potentiometer until the meter indicates 20 volts.
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OSCILLATOR LEVEL ADJUSTMENT
6
Set the input selector of the TL test set for a 600-ohm terminating measurement.
7
Connect the TL test set voltmeter to the EQUIP OUT jack on the control panel.
8
Adjust the OSC OUT potentiometer on the control panel fully clockwise.
9
Adjust the OSC LEVEL potentiometer until the voltmeter indicates 0 dbm.
10
Turn the OSC OUT potentiometer counterclockwise until the voltmeter indicates -7
dbm.
@ American Telephone and Telegraph Company, 1962
Printed in U.S.A.
Page 1
ISS 1, SECTION 409-310-502
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STEP
PROCEDURE
2600-CPS PILOT FREQUENCY ADJUSTMENT
11
Set the KS-14510, List 1 volt-ohm-milliammeter to the 12-ma scale and connect the
meter to the RC jack on the control panel.
12
Adjust the 2600-cps trimming capacitor C20 until maximum current is indicated on
the meter.
13
Disconnect the voltmeter from the circuit.
INTERROGATION FREQUENCY ADJUSTMENT
14
Set the input selector of the TL test set for a 600-ohm terminating measurement, and
connect the TL test set voltmeter to the REC AMPL OUT jack on the control panel.
15
Depress the first station key and, while this key is depressed, adjust the 700-cps trimming capacitor C9 for a maximum meter indication.
Note: This is a measurement of the level of the interrogation tone after it has been
transmitted through the interrogation loop. By adjusting the frequency of the tone for
a maximum meter indication, the frequency of the tone is matched to the minimum
loss point of the interrogation bandpass filter at the first station.
16
Release the first station key and depress the second key. While this key is depressed,
adjust the 850-cps trimming capacitor C10 for a maximum meter indication.
17
Follow the procedure of Steps 15 and 16 for each station tone used on the system.
DETECTOR SENSITIVITY ADJUSTMENT
18
Set the input selector of the TL test set for a 600-ohm terminating measurement and
connect the test set voltmeter to the EQUIP OUT jack on the control panel. Adjust
the OSC OUT potentiometer until the voltmeter indicates -9 dbm.
19
Remove the voltmeter and connect between the EQUIP OUT jack and the MON DET
IN jack on the control panel.
20
Insert a 262B 600-ohm terminating plug in the REC AMPL OUT jack.
21
Turn the DET SENS potentiometer fully clockwise.
22
Slowly turn the DET SENS potentiometer counterclockwise until the PILOT lamp
is extinguished. Repeat the procedure of lighting and extinguishing the PILOT lamp
until the DET SENS potentiometer is at a point where the pilot lamp just goes out.
Note: If the DET SENS potentiometer does not have enough range to perform Steps
20 and 21, check the adjustment of relay K5 per Section 040-267-701.
23
Remove the cord between the EQUIP OUT jack and the MON DET IN jack and remove the terminating plug from the REC AMPL OUT jack.
24
Repeat Steps 6, 7, and 10.
TRANSMITTING AMPLIFIER GAIN ADJUSTMENT
25
Set the oscillator on the TL test set for a 0-dbm 2.6-kc output in accordance with Section 104-440-300.
26
Connect between the TRANS AMPL IN jack on the control panel and the OSC OUT
jack on the test set.
Page 2
ISS 1 , SECTION 409-31 0-502
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STEP
PROCEDURE
27
Connect between the EQUIP OUT jack on the control panel and the VM IN jack on
the test set arranged for a 600-ohm terminating measurement.
28
With the OSC CHK key depressed, adjust the gain of the TRANS AMPL per Table A
until the voltmeter indicates +6.5 dbm.
TABLE A
Screw Adjustments for Various Manual Gain
Adjustment Ranges on the 2278 Amplifier
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RANGE
db
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NETWORK SCREW POSITIONS
51
52
53
21 to 35
Closed
Open
Closed
10 to 24
Open
Open
Closed
-1 to 13
Open
Closed
Open
Release the OSC CHK key and remove the TL test set from the circuit.
ALARM INDICATING CIRCUIT CHECK
30
Insert a 262B terminating plug in the REC AMPL OUT jack on the control panel.
Observe the following:
(a) PILOT lamp is extinguished.
(b) After approximately 35 seconds, the ALM lamp is lighted and the office alarm
is sounded.
Note: If the above observations cannot be made, check the adjustment of relay K5
in accordance with Section 040-267-701. If this relay meets its requirements and the
observations cannot be made, replace thermal relay K3.
31
Depress and hold down the ACO key, remove the terminating plug, and observe that
the PILOT lamp is lighted and the ALM lamp is extinguished.
CHECK OF ORDER-WIRE LEVELS AT THE NEAR-TERMINAL RADIO STATION
32
On initial installation, choose the A pad at the near-terminal radio station in accordance with Note 105 on SD-97041-01, Dl.
Note: The A pad is used to compensate for the length of the connecting facility be-
tween the order-wire and alarm control panel and the near-terminal radio station. The
level of the 2600-cps tone at the output of the control panel is -7 dbm, and this tone
must be at a level of -22 dbm at the output of the A pad.
33
Set the input selector on the TL test set for a 600-ohm bridging measurement.
34
Connect between the OW OUT jack on the order-wire panel at the near-terminal
transmitter-receiver bay to the VM IN jack on the TL test set.
Page 3
ISS 1, SECTION 409-310-502
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STEP
PROCEDURE
35
Contact the attendant at the control station via the order wire circuit and have him adjust the OSC OUT potentiometer until the voltmeter indicates -33.5 dbm.
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Note: Be sure that voice on the order wire circuit does not interfere with the meter
indication.
36
The attendant at the control station should now repeat Steps 6 and 7. The level at the
EQUIP OUT jack should be measured and recorded for future reference.
ALIGNMENT OF THE RETURN VOICE-FREQUENCY IVFl TRANSMISSION PATH
Note 1: Before proceeding with the rest of the steps in this section, the requirements
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stated in Section 409-303-501 concerning system alignment must be met.
Note 2: In Steps 40 and 45, it is assumed that the level at the OW IN jack is -22 dbm
on the rear end terminal. The level at the REC AMPL OUT jack on the control panel
must reflect any deviation from the -22 dbm level at the OW IN jack on the nearterminal order-wire and alarm panel. When setting the gain of the amplifiers in the
VF line from the near terminal to the control panel, remember that if the level at the
OW IN jack is 1-db low, the level at the REC AMPL OUT jack must be 1 db below the
normal level.
37
Set the input selector on the TL test set for a 600-ohm bridging measurement, and
connect from the OW IN jack on the near-terminal order-wire panel to the VM IN
jack on the TL test set.
Note 1: The nominal level of 2600-cps tone at the OW IN jack is -22 dbm, but this
level may vary in accordance with the variations of net loss of the radio system as
stated in Section 409-303-501.
Note 2: Steps 38 and 41 are to be performed on systems which do not employ a receiv-
ing amplifier at the order-wire and alarm control station.
38
Set the input selector on the TL test set for a 600-ohm bridging measurement, and connect between the MON DET IN jack on the control panel and the VM IN jack on the
TL test set.
39
A craftsman at the near-terminal radio station must contact the attendant at the
control station via the order wire circuit.
40
The gain of the A amplifier at the near-terminal radio station must be adjusted in
accordance with Table A until the voltmeter at the control station r~ads 0 dbm.
41
Disconnect the TL test set from the circuit.
Note: Steps 42 through 46 are to be performed at stations employing a receiving am-
plifier at the control station.
42
Set the input selector on the TL test set for a 600-ohm bridging measurement and connect the P2DG cord to the voltmeter jack on the test set. Remove the leads from terminals 18 and 19 of TSA (TSA is located on the bay framework to the left of the radio
equipment). Holding the pins of the P2DG cord against the screws of terminals 18
and 19 of TSA, adjust the A AMPL on the order-wire panel until the voltmeter indicates -4 dbm.
43
Reconnect the leads to terminals 18 and 19 of TSA which were disconnected in Step 42.
Page 4
ISS 1, SECTION 409-310-502
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STEP
PROCEDURE
44
At the order-wire and alarm control station, set the input selector of the TL test set
for a 600-ohm terminating measurement and connect from the VM IN jack on the test
set to the REC AMPL OUT jack on the control panel.
45
Adjust the gain of the REC AMPL until the voltmeter indicates 0 dbm.
46
Remove the TL test set from the circuit.
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Note: On initial installation the calibration procedure associated with trouble location
by net loss measurement of interrogation tones as stated in Section 409-303-501 should
be made at this time.
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Page 5
5 Pages
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