barrett 2050 - Barrett Communications

barrett 2050 - Barrett Communications
BARRETT 2050
Advanced HF SSB Transceiver
BCA20008/BCA90017 Interference Suppression Kit
1.
General
Satisfactory suppression cannot be achieved if faults exist in the vehicle/vessel
to be suppressed. Cracked distributor caps, worn commutators or burnt contacts
may not yet be seriously degrading vehicle performance but will generate very
high radio frequency noise levels. Before attempting to suppress noise,
problems described above should be sought out and rectified.
2.
Ignition Systems
Audible as a 'popping' noise - frequency varies with engine speed.
2.1
High Tension
High tension wiring should be of the impregnated neoprene type. Suppression
cables using graphite powder in a paper core are not reliable. If necessary
replace with a suitable set of suppression cables recommended for the vehicle.
All high tension wiring should be separated from any other wiring and should be
placed as close to the metal block of the motor as practical to reduce radiation of
any RF noise.
2.2
Low Tension
Ensure that the wire from the distributor points to the ignition coil is as short as
possible and that it is not loomed together with any other cables. If the wire length
exceeds 200mm it should be replaced by a screened wire. This may be coaxial
cable with the shield connected to ground or simply consist of a twisted pair of
wires, one used for the distribution/coil connection and the other earthed at both
ends. Keep all wiring as short as possible.
In some cases the wiring from battery to coil may require suppression.
In this case use the FI-07630 noise filter supplied in this kit.
3.
Battery Charging Systems
3.1
Alternator or generator
Audible as a whine - frequency dependant on engine speed.
Fit an FI-07630 noise filter as supplied in this kit in series with the main charging
output of the alternator. If a satisfactory earth point cannot be found on or
immediately adjacent to the alternator then the alternator/filter connection should be
screened as in section 2.2 above.
Generators are treated in the same way as alternators.
BCM20008/1
3.2
Charge regulator
Audible as a 'sizzling' noise above engine idle speed. The alternator/regulator
control ('field') wire should be removed from any other wiring by replacing with
screened wire as in section 2.2 above. Capacitors should not be connected
between this wire and ground as they may damage the regulator.
4.
Instrumentation
Some vehicles use thermal chopping regulators and/or sensors within their
instrument systems. These may be heard as a noise similar to the charge
regulator which starts 5 to 20 seconds after the engine is started. This can be
suppressed using capacitors on the supply side and screening on the
switched side of the device.
5.
Accessories
Windscreen wipers, fans and all other electrical accessories should be
checked to ensure they do not contribute RF noise. They can be suppressed
using FI-07631 filters or capacitors and the installation method given in the
FI-07631 application note.
6.
Bonding
All metal objects on a vehicle/vessel should be bonded to one common earth
with reliable connections. Ensure that the body of a vehicle is connected to
chassis bypassing rubber mounts.
Heavy duty earth straps and copper braid are supplied for this purpose.
FI-07630 Alternator noise filter Application Notes
Alternators can produce substantial amounts of noise that interferes with HF
transceivers. The interference varies in pitch with engine speed, and it may be
readily distinguished from the rough buzz of normal petrol engine ignition noise.
The FI-07630 filter is specifically designed to control alternator or generator radio
frequency interference. It is a pi-type LC filter using self-fusing metalised-film
capacitors and solid epoxy incapsulation for reliable service in the severest auto
or marine environment. Each will handle up to 60 amps continuously. Filters
may be paralleled to handle higher currents.
Installation
To Battery
FI-07630
Alternator
FI-07630
Optional second filter
Find a point on the alternator or within 200mm of it on the engine where
the filter can be mounted. Orientate the filter to allow access to its terminals after
it is mounted. Carefully clean any paint or scale around the mounting area so as
to assure good electrical contact between the filter case and the alternator case
or engine block. Mount the filter.
Disconnect the negative terminal of the battery. Locate the heavy positive
(red) output lead from the alternator. Cut this wire where it runs near the filter.
Strip the insulation back by about 10mm, crimp and solder suitable ring lugs
and secure to the filter terminals. Reconnect the battery.
NOT WARRANTED OR FAA-EVALUATED FOR USE ON AIRCRAFT
FI-07631 Electrical accessory filter Application Notes
Noise from accessories such as small DC motors used for bait pumps, fuel
pumps, bilge pumps, windshield wipers, electric heads and the like can also
interfere with HF radio systems. These sources of the noise are easily identified
by turning the accessories involved on and off while listening to the HF
transceiver. The interference will sound much like the motor itself.
Motors - Fig. 1 shows the FI-07631 filter installed to suppress a small DC motor.
The filter base plate is mounted to the motor frame or mounting plate. Paint or
scale must be cleaned away in order to provide a good electrical contact between
the filter and the motor frame. Where the two motor wires (+ and -) pass near the
filter, carefully strip off about 10mm of the insulation and secure the bared wire
under a filter terminal screw. Be sure each wire runs from the motor to a filter
terminal and then continues from that filter terminal to the battery.
Voltage regulators - older mechanical type voltage regulator used with both
generators and alternators generates substantial radio interference. This type
usually has a removable sheet-metal case whereas the solid-state type is most
often encapsulated in a smaller metal case. The interference sounds like an
intermittent frying noise, and it will change in nature and severity as the battery is
brought to full charge.
Most of the new solid-state transistorised voltage regulators used with
alternators do not produce objectionable radio interference. The few that do are
treated the same as the mechanical types.
Installation
Fig. 1
Fig. 2
Shielded or
twisted wire
F
A
B
DC Motor
FI-07631
Field
Output
Alternator
To
Battery
Voltage
Regulator
FI-07631
To Battery
Mount the FI-07631 filter on the regulator frame itself as indicted in Fig. 2,
cleaning away any paint or scale so as to assure a good electrical contact to the
filter case. Where each of the wires from the regulator except the field wire
passes near the filter, strip the insulation from 10mm or so and secure the wire to
a filter terminal screw.
Field wire - the wire connecting the alternator or generator field to the regulator
should not be connected to a filter as above. Shielded wire may be substituted
for a single conductor, grounding the shield at both ends. Alternatively, a second
wire can act as a shield if it is twisted around the field wire (perhaps one turn per
25mm) and grounded at both ends.
INTERFERENCE SUPPRESSION KIT CONTAINS:
ITEM
1
2
3
4
5
6
7
8
9
QTY
1
1
1
1m
4
4
4
1
1
DESCRIPTION
Noise Filter FI-07630
Noise Filter FI-07631
Earth Strap
Earth Cable
8mm Terminal Lugs
10mm Terminal Lugs
Capacitors
Suppressor
Clamp
BARRETT P/N
FI-07630
FI-07631
PO-07633
CA-06518
CN-07640
CN-07641
CP-01515
NB-04563
NB-04565
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising