Barrett Communication BARRETT2040HF HF SSB Transceiver User Manual Part 5
Barrett Communication Pty. Ltd. HF SSB Transceiver Part 5
Part 5
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| Document ID | 729125 |
| Application ID | SNPapE1OJfWnYQ4p86zjCQ== |
| Document Description | Part 5 |
| Short Term Confidential | No |
| Permanent Confidential | No |
| Supercede | No |
| Document Type | User Manual |
| Display Format | Adobe Acrobat PDF - pdf |
| Filesize | 33.13kB (414138 bits) |
| Date Submitted | 2006-11-16 00:00:00 |
| Date Available | 2006-11-16 00:00:00 |
| Creation Date | 2006-11-16 14:04:57 |
| Producing Software | Adobe Acrobat 6.0 Paper Capture |
| Document Lastmod | 2006-11-16 14:05:08 |
| Document Title | Part 5 |
| Document Creator | Network ScanGear Ver.2.01 |
BARRETT 2050 HF SSE TRANSCEiV
it is recommended that the uansceiver chassis is connected to ground using the
bolt on the rear panel to stop pick-up ol unwanted noise lrorn local power supplies
and electrical equipment.
Power supply
All Banett transceivers require a supply voltage or 13.8 me. In most vehicles or
vessels this is available lrom the battery, in the case at vehicles with a 24V system
a 24V to 12V converter rated at 25 amps should be used (Barrett F/N ECASOOM).
In fixed station installations where mains power between BBVAC and 256VAC is
aimilable, a Barrett 1022 power supply should be used.
In base station installations where no mains supply is available a Barrett 2001 solar
power supply is available.
Note:- some installations use an AC battery charger to float charge the supply
battery. Battery chargers can produce electrical noise irorn the rectifier diodes.
This noise causes a static type at interference in the receiver. It may be necessary.
thereiore, to switch on the battery charger whilst the transceiver is in use. If float
charging oi batteries Is required or installations with unreliable AC power supply, it
is recommended that a Barrett 2022 be used as this provides a boost and iioat
dierge facility to maintain a battery without the noise problem described above.
Voltage drop
The average current consumption or the transceiver is low but during transmission
or voice peaks, high current is needed tcr short intervals. This means that the
power supply cable must be heavy enough to supply these short duration current
peaks without excessive voltage drop. Freterably use only the power cable supplied
with the transceiver. It extia cable is required use a cable with a conductor square
area of no less than 5mm. Unwanted voltage drop will also occur it incorrect wiring
techniques such as poor choice or connection points and incorrect use of terminal
lugs are used.
Protection ruse
The transceiver is provided with adequate internal protection. However, the fitting
at an external ruse is considered necessary, not for protection or the transceiver
itself, but tc ensure that In the event oi damage to the cable, a fire risk does not
exist. The fuse used must be installed in the active Wire as close as possible to the
battery. and must be of a type which has a Icw voltage drop attire peak currents
expected.
Notez- In-llne 3AG glass fuses are not suitable. An ATC automotive blade type
fuse rated at 25A with a suitable high current ATC iuse holder rated at 30A or more
should be used. These type 01 luses and holders are contained in our standard
installation klt (Barrett PIN BCA20004) or are avallable individually (Barrett FIN
BCA20021)
= 201 01237
BAR TT 2050 HF SSB TRANSCElVER
Antlnna
The antenna is a most critical part or the complete radio installation It must accept
the output power from the transmitter, radiate that power with minimum loss and in
the receive mode, accept weak signals ior input to the receiver.
Incorrect anuenna installations will yield poor system performance and are often the
cause or complaints of poor transceiver performance,
A range of antennas is available irom Barrett to suit most small fixed stations.
Detailed instrucfions are included with each antenna.
912 Single Wire Broadband DIpoI-s - Barrett PIN BC91201
Banett 912 single wire broadband dipoles are ideal for base stations that require
operation on multiple frequencies throughout the HF speetrum using a single
antenna.
The 912 antenna can be mounted either in a horizontal or inverted 'V' configuration
as illustrated in the following diagrams. In the horizontal configuration the maicr
radiafion direction is broadside to the antenna. When mounted in the inverted ’V'
configuration the antenna becomes iairly omni directional. In the horizontal
configuration the minimum distance between the masts is 49 metres and the
recommended mast height is 15 metres. In the inverted ‘V' configuration the
recommended mast height is 15 metres and
125 watt standard single wie broadband dipnle
at this height the 2 metre stub masts are each Installed ata minimum or 19 metres
from the mast base. In locations with limited space the antenna can he mounted
with the ends past the load resistots drooped down towards the ground. White
nylon supports located just past the load resistors are provided to attach haiyards
ior this configuration. In this configuration the minimum distance between masts is
reduced to 33 metres. Support towers may be either lattice masts as illustrated,
202 of 237 l=—=
BARRETT 2050 HF SSB TRANSCEIVER
tubular telomosts or other support structures that may be available locally. It Is
recommended that the halyards used to support the antenna be either UV stabilised
Dacron cord or wire rope and mat pulleys shauld be at stainless steel oonstmction.
Install the antenna as illustrated in the diagrams, in the inverted ’V‘ configuration the
eye on the top at the balun is used to attach the support halyard.
a _,_.~‘.,,.z‘~«,‘m.\
£1,354. .
125 wall standard single wire bmadbanfl dipole in an Inverted 'V"
As with all antenna installations ensure the antenna is as far in soumes of
electrical Intelference as possible and In a position that makes possible
for the antenna to come In contact with high voltage overhead mains erlngr
125 wait standard slngle wire bl'wdhand dipole m a limited space configuration
203 at 237
BARRET 50 HF SSB TRANSCEIV
912 Mutt—Mire Broadband Dipoles - Barrett P/N's 8091200, 8091202 and
8091203
Barrett 912 broadband dipoles are ideal for base stations that require operation on
multiple lrequencles throughout the HF spectrum using a single antenna
125500 wad imiIIi wine broadband dipole
The Barrett 912 antenna can be mounted either in a horizontal or Inverted ’V'
configuration as illustrated in the following diagrams. In the horizontal configuration
the major radiation direction Is broadside to the antenna. When mounted in the
inverted 'V' configuration the antenna becomes tairly omni directional. In the
horizontal configuration the minimum distance between the masts is 32 metres and
me recommended mast height is 15 metres. In the inverted v configuration the
recommended mast height is 15 metres and at thls height the 2 metre stub masts
are each installed at a minimum ol 19 metres from the mast base. In this
configuration the mast must have an onset or out—(igger bmcket. at least 0.8 metres
iong, to itoid the antenna away item the mast. Support toweis may be either lattice
masts as illustrated, tubular telomasts or other support structures that may be
available locally. It is recommended that the halyards used to suppofl the antenna
be either UV stabilised Dacron cord or wire rope and that pulleys should be ol
stainless steel construction.
204 of 237 g
SCEIVER
BARRET
50 HF SSB
Install the antenna as illustrated In the diagrams, in me inverted 'V' configuration the
eye on the (op oi the balun is used ta attach the support halyard. In the horizantal
configuration the balun hangs belaw the antenna.
2125/500 wan mum wlre broadband dipole in an invened 'v' configurauon
As with all antenna installations ensure the antenna is as far from sources of
electrical interference as possible and In a position that makes it Impossible
fer the antenna to come in contact with hlgh voltage overhead mains wiring.
1000 wall Mulfi ere Broadband Dipole
l===—== 205 Oi 237
BARRETT 0 HF SSE TRANSCElV
913 serles helical dipoles - Banelt P/N's BC91301 ID 5091305
913 series helical dipole antennas are compact and easily installed, having
exlremely narrow bandwidth characteristics and a perlotmanoe approaching that of
a wire dipole when used at freguencles over 4.5 MHz. The helical dipole antenna is
led by a single coaxial feeder and can accommodate up to 5 irequencies.
fluflagfikm“
3 frequency helical dipole
The 913 helical dipole requires a 50mm diameter mounting pole. This pole should
be long enough to place the helical dipole at least 5 metres above any obstruction.
Alternatively the helical dipole can be mounted on top oi a mast or towerc Make
sure that the site selected for the antenna is as far from any source of electriml
interlerenoe as possible and that under no cltcumslanoes it can come in Contact
with hlgh tension power lines.
Alter mounting the helical dipole hub on the mounting pole, remove the liont
circular cover, pass the coaxial cable through the hole at the bottom oi the hub.
Screw the UHF connector into the balun. Now screw the helical dipole elements
onto the hub Each element has its frequency marked on the brass ferrule used to
screw the element onto the hub. Assemble the helical dipole elements in the
positions on the hub as indimted by the diagram enclosed in the hub. Failure to
assemble the helical dipole as indicated in this dlagmm will cause tuning problems.
206 of 237 a
BARRETT 2050 HF SSB TRANSCElVER
Hub detail
3 frequency helical dipole
Helical dipoles are manufactured to specific frequencies, but may require fine
tuning aflar installation. To enable this the dipole elements have an adjustable
length tip to allow fine tuning for optimum VSWR during Installation. install the
antenna in its final posltlon and check the VSWR on each of the frequencies that
the antenna was manutadured tor. Should the VSWR be greater than 1.5:1 the
antenna will require adjustment. If a tunable transmitter is available, determine on
each lrequency the helical dipole was manufactured lot, at what frequency the best
VSWR is obtained, If this occurs at a frequency below the required trequency than
the tips will have to be shortened on the pair ot elements corresponding to that
frequencyu If the best VSWR occurs on a trequency higter than the required
frequency then the tips will have to be lengthened. Adjust both ends by an equal
amount and repeat the above sequence until an optimum VSWR is obtained, It a
tunable transmitter is not available use a method 01 trial and error to adjust the
length at the tips, a little at a time, until an optimum VSWR is obtained. Remember
always adjust each pair of elements by the same amount at each adjustment.
=—==== 207 of 237
BARRETT 2050 HF SSB TRANSCEIVER
915 wire dipole - Barrett PIN 5091500
Single frequency wire dipole antennas, spot-tuned to the required operating
frequency(s). are the most efficient antennas for use in HF base slaticrns, They are
slmple to install and have a relatively narrow bandwldlh,
smile lreqnency wine (finds
Dipole anlennas should be mounted at least 1/2 wavelength from the ground.
Dipoles may be mounted either between two towers or in an inverted “V'
configuration (requires only one mast), As a guide. when Installing the masts, the
length between insulators of a halt wave wire dipole is 142/(frequency of dipole in
MHZ) metres. To this an allowance should be made for extra insulators 8nd
halyards.
i .a 3.7MHz dipole - length between the Insulators = 142/31 =38.3B metres.
ere dipoles supplied by Barrett are Dre—cut to a specified irequency but have
adlustable ends. Tness adjustable ends allow fine tuning lor optimum vswn during
lnsmllalion. To fine tune a dipole install the antenna In its final position and check
the antenna VSWR. Should the VSWR be greater than 5:1 the antenna will require
adjustment.
Single frequency wire dipole in an
lrwefled 'V' configuration
208 of 237
ARRETT HF SSE TRANSCEIVER
W a tunable transmitter is available. determine at what frequency the best VSWR i$
obtained. ll this occurs at a frequency below the required frequency the dipole is to
long. il it oocurs on a lrequency higher than the required trequency men me dipole
is to short. Drop lhe dipole and adjust both ends by an equal amount and repeat
the above sequence until an optimum VSWR Is obtained. If a tunable transmilwr is
not available use a method of trial and error shortening or lengmening the dipole
ends, a little at a time, until optimum VSWR is obtained. Remember to always
adlust each end by the same amount as the other every time.
Several slngle frequency wire dipoles positioned between
two towers.
_===== 209 of 237
BARRETT 2050 HF SSB TRANSCEIVER
Barrett 911 Automatic Antenna Tuner for base station installations
Antenna
Various antenna configurations. such as verliml whips. Iong-Mn'res and loops. can
be used lor base station Insballations. using the Barrett 911 automatic antenna
tuner. In general however the following points should be considered:-
The antenna should be mounted as lar away as possible lrom buildings, trees.
vegemtion and sources of electrical interference. ll metallic masts or supports are
used, arrange Insulators to ensure the antenna is spaced at least 2 metres lrom the
mast, Remember the radiating part ol the antenna starts at the tuner. The location
ot the bottom portion of the antenna is very important.
Horiloflwl wire antennas have maximum radiation broadside to the antenna when
the lrequency Is less than 1/4 wavelength. Radlafion is at a minimum at the end
points of the antenna. Inverted "v" Installatlon ol horizontal antennas minimises the
directivity and Is recommended lor omni-directlcnal coverage.
High Voltages are present on the antenna system, The antenna tuner and antenna
should be located or protected so lhal there is no possibility ot accidental oonwct.
Transceiver and tuner mounting
The transceiver should be mounted in a suitable position allowlng easy operator
access. The antenna tuner should be mounted, preferably out of the weather. and
as close to the ground (earth) point as possible. The interconnect cable supplied
with the antenna tuner should be routed, away (mm other cables, back to the
transceiver and connected as indicated in the diagram. The maximum interconnect
cable should be less than 25 metres.
Ground tearthi system
The ground (earth) system Is a key part or the overall antenna system and
consequently the system operation, An inadequate ground system is the primary
cause ol poor performance and tuning problems. There is little point in Installing
the antenna unless a good ground system can be provided. In areas of good
ground conductivity (ie. ground always damp), an elfectlve ground can be made
through a grounding rod. This should be approx, 3 metres in length and should be
installed as close to the tuner as possible. Several rods bonded together will
improve the ground contact. In some cases metal water plpes may be used as a
ground providing:-
- The water pipe is close to the tuner and the water pipe enters the ground
close to the timer.
» There are no joints or couplings in the pipe that will increase the resistance
path to ground.
- The water pipe enters so" with good conductivity.
21007237 —====—
EARRET 0 HF SSB TRANSCEiVER
- A low resistance joint is made with the water pipe.
Frequently the ground oonduottvlty win not he sulfioient to provide a safisfactory
ground for tha Barrett 911 tuner. This will almost certainly be the Case in well
drained sandy soils or on rock, In these cases a oounterpolse must be used as a
ground system. This will also be the case in rooltop Installations where no existing
ground plate (such as metal roofing exists). A counterpoise can consist oi radial
wires or a mesh made of materials such as chicken wire. Ir radial wires are used the
counterpoise should consist or at least a to to radial wires, each radial being at
least 5 metres in length. when radials or mesh are used at ground level It Is
recommended that they be hurled a few centimetres below the surface.
Electrical checkout
Aner mechanical installation is complete select the highest frequency to be used on
the transceiver. A directional watt-meter such as a bird model 43 should be
Inserted in the coaxial transmlsslon line between lha transceiver and the timer. The
tune mode on the transceiver ls then energised (refer to the transoeiver user
manual). Upon application of RF energy, the tuner should start to tune, indicated
by the ‘clattering' of the tuner relays. After a few seoonds the relay nolse will cease,
the transceiver shwld indicate a successiul tune and the wattmeter reflected
power should indicate a kyw Value consistent with a VSWR of better than 221. NOW
select the lowest desired irequency on the transceiver and repeat the above
procedure. The result should be the same, except that the tune cycle may take
somewhat longer. W the above procedure does not give the results as indicated
check that the antenna length and connections are correct and re-check all ground
(earth) contractions.
Note:- When received. the Barrett 911 automatic antenna tuner memory system will
usually not have any pre~stored tuning inlon'nation appropriate to your installation
To allow the 911 m 'Ieam' its tuning information simply proceed from one channel to
the next allowing the normal tune cycle to take place. Each successlul tune is
‘memorised‘ so that when that channel is re—selected the tuner will almost
instantaneously retune to that frequency.
=== 211 ol237
212 of 237
BARRETT HF SSE TRANSCENER
Connectlon details - 2050 transceiver and 911 automatic antenna tuner In a
base station configuration.
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BARRETT 20 HF SSB TRANSCElV
Mobile installations
Tmnsoeiver pee on
The following points must be considered when mounh'ng the transceiver.
safety
It is essenh'al that the transceiver be mounted |n a place where It cannot cause
injury to the occupants ol the vehicle in the event dla motor vehicle accident.
For this reason overhead mounting Is not generally recommended and "under dash”
mounting must take Into account the possibility ol injuring the legs ol tront seat
occupants.
Convenience
The chosen position for the transceiver or control head. (if a remote controlled
model is used) should be one which allows convenient operation.
Positions which are often used are:
- on the transmission hump
- in place or the glove box
- behind the seat
- under the dash board (it safe)
Where a remote controlled transoe'wer is used. only the control head need be
mounted convenient to the operator. The transceiver may be mounted under a
seat, in the luggage compartment or any other out of the way place within the
vehicle (which allows tor sufficient cooling).
All equipment should be positioned in such a way that convenient access tor
maintenance is provided.
strength
it must be assumed that the vehicle will be used on rough roads and In many cases
all road. Hence mounting or equipment must take Into account me severe vibration
and shock that can be expected.
Transceivers may only be mounted to structural components or the vehicle body
and not on dress panels or plastic “mtertor panels. In some cases, the area around
the transce'nrer mounting may need reinforcement,
Precautions should be taken to ensure fixing screws etc. cannot ln'brate loose.
213 of 237
BARRETT HF SSB TRANSCEIVER
Air circulation
Most transceivers rely on air flow amund cooling fins to dissipate heat generated by
the transmitter. The mounting position must allow free airflow around these fins.
Obstruction
The installation Di 8 transceiver into a vehicle should not inhibit the normal use at
the vehicle. Beicre finally selecting equipment positions. check that normal
operation of steering, loot pedals, gear ohangs, hand brake etc. are not impeded,
and that heater or air-conditioning outlets, glove box and doors are not obstnlcted.
Always check that the drilling or mounting screw holes will not damage eleotncal
wiring, heater hoses or hydraulic lines.
Power wiring
Connect the red posifl've and black negative wires truth the transceiver power cable
to the positive and negative terminal or the battery, Do not connect to the ignition
switch or lntemal ruse panels as vehicle wiring to these points is or insufficient
ounent capacity, causing voltage drop and possible noise interference.
- m a suitable 25A ATC fuse and holder (Barrett P/N BCA20021), as near as
practicable to the battery connedion in the positive (red) wire.
- route the power cable away from high tension ignition wiring.
- secure the power cable, either to other wiring or the vehicle body. with
suitable cable ties.
- where wiring passes through bulkheads. pnwide appropriate protection to
prevent Insulation being damaged.
2140l237 ===—==
BARRETT
0 HF SSB TRANSCEIVE
Connection details - 2054) transceiver with moblle pack and 914 manual
tapped nwblle antenna
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0 9" Mam‘ ”PM Wm? WM 2050 Transceiver body
lml head ' a mansion speakersuwlied
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came Mm Rm? mnneclors
PIN BCAZDOOS
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Cnnmcflon fa external fan vnil opfinn
Coaxial mic am connedms FIN scAanola
9 Heavy duty Me A homer FIN acAznozl Auxlliary summer
6 mm pawsfcable suwlled
wlm hmeeiver
699069
External 695 receivef option
215 01237
HF SSB TRANSCEIVER
Antenna
In any radio system an etfeciive antenna inswllaiion is essential. Because ol Ihe
need to reduce the size of HF antennas so that they can be fitted to a vehicle,
mobile antenna bandwidth becomes quite narrow and hence tuning Is critical. In
most cases lhe only tuning adjusu'nent that can be eitecled is adjustment to
position. Particular attention must be given to the antenna position if satislactofy
pertormance is to be obtained. Reier to the instructions supplied with the antenna
you have selected.
Antenna mounting
The antenna mounting must provide a strong secure anchorage tor the base oi the
antenna. To obtain maximum radiation, the antenna base must be well bonded
electrically to the vehicle chassis. Paint, dirt, rust, etc. should be removed irom the
respecflve fixing points. The mounting point must provide a low resistance
electrical path to the main vehicle metallic structure.
Antenna feed cables
Antenna feed cables should be run (as tar as possible) away irom other vehicle
wiring and especially away from ignih’on high tension wiring, Where passing
through body panels or lniemal bulkheads, grommets must be used to protect the
cables. Water-prool connectors must be used when they are outside the vehicle.
Voltage standing wave ratio (vswa)
After installation it is recommended that the VSWR of the antenna should be
measured for each channel. The instructions supplied with the antenna selected
will detail this operation.
215 of 237 ===
0 HF SSB TRANSCE‘VER
Connectlon details - 2050 transoelver with mobile pack and 910 automallc
inning mobile antenna
9m anamaiictming Mable anienna
2050 mm! lined
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PIN acAzmos
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Cannecfion brexmaiian unn uplion
Coaxial/comm nae PIN BCMMZ
Auxiliary mnnedor
Enema! GPS receiver Wfim
Optional 5 or 10 metre mansion cable
win ems PIN BCABODSQMD
217 01237
HF SSE TRANSC lVER
Noise suppression
Noise generated by motor or electrical accessories on the vehicle may cause
objectionable interierence to the received signal. This noise enters the receiver
either by means of the battery leads or the antenna system. Prwlding that the
recommendations concerning battery wiring given earlier in this book are followed.
noise injected via the battery lead ls unlikely to be significant. Most noise problems
result lrom pick-up by the antenna ctical cures involve either preventing the
noise from being generated or m ng it from being radiated by the wiring
connected to the noise source.
Interference suppression klt (Barrett PIN BCA90017) is available to assist in
noise suppression and contains filters, suppressing capacitors, earth straps and
fitting instructions.
The techniques involved in noise suppression include re—routing oi wiring, screening
and the use of filters. It is also necessary to maintain all electrical equipment in
good working order as worn bmshes, loose connections and the like, will increase
the amount or noise generated.
Belore attempting to cure a noise problem, the source (or sources) or noise must be
identified. Ideally, there should be no ditterenoe between background noise in the
receiver with motor and accessories on and that with motor and accessories ott.
Ir a detectable dmerenoe does exist, turn oft all accessories one by one until a
change In noise results. Continue, noting eaai contributing unit until there is no
detectable diflerenoe from the 'all oil" noise level. (For accessories such as
alternator. motors, instruments etc. a wire or drive belt may have to be temporarily
removed tor this assessment). Atler identifying each noise source. they can be
worked on one at a time until an acceptable level or suppression is achieved.
Another approach to this problem Is to remove or disconnect all possible sources at
noise then replace and suppress them in turn.
some suggestions for suppressing particular noise sources toilow:-
lgn on systems
All high tension wiring from the ignition ooil through to the spark plugs should be
kept as short as practicable, clean, and as close to the engine block as possible.
The cable should be an impregnated neoprene resistive type and the ooil must be
either mounted on. or immediately adjacent to, the engine block. The low tension
wire from the coil to the distributor contact breaker points must be as short as
possible, and not induded with other wires in a harness or loom. This wire must be
shielded it more than 300mm long. Twin flex or ‘iigure eight’ cable provides a
suitable shield when connected in lieu ot the original wire. This method is uselul lot
shielding other wires suspected or radiating noise. Do not ignore the wire to an
electric tachometer it one is fitted.
BARRETT 2050 HF SSB TRANSCEIVER
Coll to battery wiring
A low pass filter such as that supplied in the interierenoe suppression kit or similar
should be fitted at the coil end of this wire. The eanh oonnection oi the filter should
be short and wellsbonded to the ooil body.
Battery charging system
The charging system circuit consisting or either generator or alternator and a
regulator may also be split into mroe parts;
Alternator I generator to battery wiring
A low pass filter such as that supplled In the |nterierence suppression kit or similar
should be titted to the main battery lead at the alternator. The filter must be rated
for the maximum current available from the charging system. The earth lug or the
filter should be attached to the alternator body or the engine block.
Altomator to regulator control wire (generator field wlro)
This wire carries switching pulses that oflen contribute noise to the receiver.
Suppression using capacitors or filters must not be attempted slnoe damage to the
regulator may result. Separate the wire lrorn all other wiring, keep it as short as
possible and. ii longer than about 300mm it should be shielded as described above.
other regulator wires
Those are normally adequately suppressed using good low-inductance bypass
capacitors. To be etrective, these capacitors must connect to the wires to be
suppressed and to chassis with very short leads. For this reason. the “pigtall' style
of suppressor capacitor olten used with MF broadcast reoeivers is generally
inefiecfive at HF.
other noise sources
Electric motors (windscreen wipers, tans etc.)
Small electric motors can usually be suppressed with good low Inductance bypass
capacitors.
Engine Instrumentatlon
Certain types oi oil-pressure sensors and voltage regulators used in Instmment
systems contain a vibrating or thermal cycling contact. These devices can only be
suppressed by isolating and screening or wiring in the same way as described tor
the alternator to regulator control wire. Dist: ceramic capacitors with short leads
(protected with insulating sleevlng) are treguenliy userul but to prevent damage to
instrument corneas, where the use or bypass capacitors is attempted, values larger
than 1nF should not be used.
=—=—= 219 at 237
BARRETT HF SSB TRANSCEiVER
General noise suppression tips
When searching for sources ot nolse, some ot their characteristics can be helpful In
“identificafiont-
Petrol engine ignition nolse and oontact breaker noise is a sharp slaooato 'p|op'
varying with engine speed. n is only with this class oi noise that the impulse nolse
Ilmlter Incorporated within some transoeivers is etiecljve
Nolse from other sources generally has a more ‘mushy sound. That irom the
eltemator/generator may only be troublesome over e limited range of engine speed
and can also be influenced by the state of charge of the battery.
The noise from instrument regulators may depend on the battery vollege, the
reading at the instrument and the lengm of tlme the system has been switched on.
For this reason. the seamh for noise sources must be done thoroughly to prevent
noise lrom apparently reappearing after the installation has been completed.
Electric motors generate a ‘whining' sound. Do not torget to check windscreen
wipers, electric fuel pumps. heater and air conditioning fans and other motors which
operate only on an intermittent basis.
220 01237 =
BARRET 0 HF SSB TRAN
910 automatic tunlng mobile antenna - Barrett PIN 3091000
The 910 antenna plugs dlrecfly into the rear or a 2050 hansoeiver using the moles
supplied. Import: .- 2050 transceivers must have the 910 antenna option set
during programming.
The 910 antenna should be mounted In positions similar to those illustrated in the
diagrams below. Select a position free from excessive vibration. A bracket.
tabrimted to withstand the tomes and vibration that can be expected during oft-road
driving, should be used to mount the antenna to the vehicle. When locating the
mounting position tor the antenna ensure that the antenna body, when flexing on its
w‘bration mount cannot come into contact with other parts at the vehicle. The
antenna shou|d be mounted as far from surrounding objects on the vehicle as
posslble.
Preferred Mounting Positions
ABSOLUTE MINIMUM CLEARANCE
TOP VIEW
important:
Please note that the mounting
eta 910Amenna on the front of
a vehicle may be considered
illegal In some areas/nominee.
Please check wlth ywr local
transport/vehicle annuity prior
to installation on the (mm of
your vehicle.
221 of 237
BARRETT 2050 HF SSE TRANSCEIVE
Acceptable Mounting Positions
ABSOLUTE MINIMUM CLEARANCE
TOP VIEW
ABSOLUTE MINIMUM CLEARANCE
,IDP.VI£.W¥ ,,,,
EAR OFVEHICLE , . , ~
Important:
Please note Ihal me mwnllngofa
910Antenna on Ihe mm ova venue
may be mnsidsrsd illegal in some
areas/munlrias. Please check wllh
your local transport/venue ammonty
pnorle lns1allalbn on me 1mm
your vshide.
Caution? Whilst the 910 automatic (unlng mobile antenna Is deslgned to
wlthstand vlbratien to milltary specifications on tyred venlcles, some
mounting positions on large prlme-movers, particularly front mounted bull-
bars, are subject to vlbrallon that far exceeds this specmcallon. Do not
mount the 910 antenna in posltlons such as these as damage to the antenna
may result
222 0! 237 g
BARRETT 2050 HF SSE TRANSCEIVER
A good eanli (ground) to lhe main body of llie vehicle is essential for efficient
operation of (he anlenna. To achieve (his clean all ioinls lo here metal and use
copper braid earth siraps ii any non-melallic joints are encounteredl
Aner mounting the meln body of the antenna, screw the black ooil onto the antenna
body followed by lhe stainless sleel wnip.
Note:- Some models of the 910 anlenna have a one piece sprlng and a stainless
steel whip in place of the coil and whip.
Turn the spring bese
ll ' on to the ABS body
| / lightly by hand until
| , It can be turned no furlher.
Using a suitable tool
(le; spanner) turn the
lower mreaded part of the
spring base a furlher
2030 degrees clockwise
wtllle holding the top of
the ABS antenna body
with a free hand,
A5mm HOLE IS PROVIDED
ON THE MOUNTING STUD
T0 ACCOMMODATE A
PADLOCK IF REQUIRED
223 of 237
0 HF SSE TRANSCElVER
The antenna is supplied with a pre-tcrminated 1.5 metre cable tail. Thls should be
routed into either the engine compartment or boat (tmnk) at the vehicle. A 6 metre
pre-terminated extension cable is supplied to connect the antenna to the
transceiver (thls cable may be extended to 12 metres by use at another extension
cable). It the joint between the antenna stub cable and the extension able is in an
exposed positlon, a butyl rubber sel' amalgamating tape should be used to seal the
pint. Do not wrap thlsjolnt it it cannot be made completely watertight as water will
collect In the joint and cause it to corrode.
To test the antenna, attach a VSWR meter ln Ilne with the coaxial cable at the
transceiver. Select any channel on the transceiver and activate PTT or use the tune
funotron # on the transceiver. The antenna should tune (indicated by the sound at
relays ctattering), within 2 sewnds. Use the tune function to check the VSWR of
the antenna, it should be less than 2:1. It the tune sequence does not occur check
all wiring thoroughly and check that the transceiver is programmed for use with a
510/910 antenna. It the VSWR is not within an aweptable limit check the earth
(ground) bonding ot the antenna base to the vehicle.
To secure the whip if driln'ng under low objects or tor use at the 910 In an NVIS
mode (tor short range communication) secure the whlp as illustrated in the diagram
below with the steel wire clip and lanyard supplied.
important:
Please note thet the mounting at
a stoAnlenna on the front ota
vehicle may he considered illegal
in some areas/countries. Please
check with ytmr local transport/
vehicle authority prlor to
installation on the front of your
vehicle.
224 of 237
0 HF SSE TRANSCEiVER
914 Selle! manual tap whip antenna - Barrett PM 5091401 to 5091424
Installation
914 series manual tapped whip antennas are mounted on vehicles using a heavy
duty base and spring (Barrett F/N BCASMOO). The whip should be mounted on the
vehicle in positions such as those illustrated in the diagrams below. A bracket.
labricated to withstand the torces and vlbration that can be expected during offload
driving, should be used to mount the antenna base and spring to the vehicle. When
locating the mounting posltlon tor the antenna. the ring located above the label at
the bottom of the whip should be level with the surrounding ground plane. e.g. the
bonnet oi the vehicle or the root 0! the vehicle. Ensure that the mounting bolt on
the base and spring is elecmcally bonded to the chassis or the vehicle via a very
low raistance path e. clean all joints to bare meal and use braid earth straps if
any non—metal joints are encountered. Use only good quality coaxial cable and
water prooi UHF connectors (such as those supplied by Barrett Communications).
Do not use PL-259 UHF connectors.
When running the coaxial cable from the antenna to the transceiver avoid sharp
comers and heat such as that generated by the manifold oi the engine. Alter
installing the antenna check the antenna VSWR on each channel. Generally If the
antenna has been mounted in the positions as illustrated, the VSWR will be less
than 1.61 and’no adlustment Is necessary. If the VSWR Is not lower than 2:1 the
antenna to ground capacitanoe in that Installan‘on is probably outslde of the design
range ot the factory set tuning. Consideration may be given to retuning the whip ll
Ihe VSWR is so high as to cause the trans'nitter ALC system to begin to reduce
power (to protect the transmitter).
= 225 of 237
BARRETT 2050 HF SSB TRANSCEIVER
For each frequency which will not tune correctly you vln'll need to determine whether
the tunin high or low in trequency. Generally any irequenciee which will not tune
will always be out the same way. When the antenna is made mosttrequencies are
deliberately made on the low frequency side and adjusted upwards by the
placement 0! "tuning rings”. Tuning rings are single short circuit rings or 20 amp
fuse wire placed on the windings or an individual part at the antenna. A tuning ring
inductively raises the frequency of the section ot antenna over which l is placed.
it must be understood that the tuning Of an antenna on a particular vehicle or
installation may not hold tor other vehicles or installations. To determine whether
any panicutar trequency tap is high or low hold the tune key down on the relevant
frequency and observe the VSWR on a suitable meter. Get an assistant to slowly
move his outstretched arm closer to the antenna tap in use.
l! lire VSWR gets better then the
antenna is too high in frequency.
This indicates that there is Insuttlctent
antenna to ground capacity. Usually
this happens when the antenna is
mounted too tar away tram the body
of a vehicle. Either re-site the
antenna closer to the vehicle or
remove any tuning rings whidi are
already on the antenna.
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Raoutnas Amuswarr, mmu was we
mums mus renew my my: uwwws
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neuteresrsnaoumcvon ntzwnr names
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sArrsmmszlsoemNED.
It the VSWR gets worse when
tollewing the above procedure then
too much capacity is already present,
this Is frequently encountered when
mounting the antenna too low on a
vehicle bumper bar or when mounting
close to bodywork as in cab-over type
vehicles. In thls case either re»s|te
the antenna turther away or add extra .
tuning rings to the frequency sections atrected until a suitable VSWR is obtained.
4—lr MINE lowzsr mam nations
, AmthENr Nlmwmsntz mime RING
Hmwsmwu MWE UPWARDS utTlLA
sAnstmRv am: IS oerAlrtEn
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7mm
Notez-Truck cab—over installations usualty produce distorted radiation patterns even
when the VSWR looks good.
When tuning is complete any new rings added should be coated with epoxy resin to
secure and protect the ring from damage. Five minute quick setting type epoxy is
suitable. it rings need to be removed they may be cut on using a sharp pair at side
cutters. Take care not to cut into the body 01 the antenna.
Note:- It the wander lead is damaged or lost and requires replacing. the number on
the first tap indicates the length 0! the replacement wander lead required.
Examptez- WI-SO indicates the length otthe wander lead was 600m. When making
a replacement wander lead ensure it is made to this length to obtain optimum
pertormance,
0 HF SSB TRANSCElVER
Operation Instructions
The 914 manual tapped whip antenna should now be screwed Into the base and
spring mounted on the iront oi the vehicle.
The operation frequency being used on the transceiver should now be
selected on the antenna. This rs done with the supplied jumper lead as indicated
in the dlegrem below and the follwving example (Note:- this is an example only and
your antenna will be manufactured with different irequency taps.)
The 914 manual tapped whip antenna used in the example has the iollowing
lrequencies:-
channel 1 4030 kHz channel 2 4760 kHz
Channel 3 5190 kHz Channel 4 5254 kHz
Channel 5 7180 kHz channel 6 8199 kHz
Channel 7 9134 kHz Channel 8 9145 kHz
Channel 9 1 0557 kHz Channel10 14567kHz
When using Channel 1. frequency 4030ki-iz, the jumper
lead should be removed from the bottom antenna socket
and flared in the vehicle.
On all other channels the jumper lead is required:-
For Channel 2, frequency 4760kHz, the jumper is
plugged into the bottom socket then wound lightly around
the antenna and the other and plugged into the socket
marked 4750,
For Channel 3. lrequeney stsokhz, the jumper is
plugged into the bottom socket then wound tlghtly around
me antenna and the other and plugged into the socket
marked 5190.
An so on to channel 10.
lluunlea a . ta "WWW t
m mnul tlw‘d whlp
utter...- win the wane"
lmw-Mhalwmad
Note:- It Is Impnmnl for correct operation of the whip amen!“ to hlvs the
right frequency tap selected as Indicated above and that the jumper lead Is
wrapped tightly around the antenna between sockets.
227 of 237
ARRETT 2050 HF SSB
Marine Installations
General
The Barrett 911 automatic antenna tuner is designed tor use in land base stah‘on
and maritime HF services. Primarily designed for operation with end-fed un-
balanced antennas such as whips and long-wires, the tuner is built in a waterproot
impact resistant. moulded ABS plastic enclosure.
Antenna selection
The 911 automatic antenna tuner will operate into almost any end-fed antenna with
a length exceeding 25 metres, providing an effective ground (earth) is used. The
antenna efficiency will be proportional to the length of the antenna and win be
maximum when the length Of the anmnna approaches 1/4 wavelength. It is
advisable to limit the wire antenna to 1/4 or 3/4 wavelength at the highest frequency
to be used.
Antenna
oh sailing vessels the antenna can either be an insulated backstay or a whip
antenna mounted verllcally, usually on the stern. Best performance will be achieved
by using an insulated backstay as the radiating length lM'll be longer than that
available when using a whip. The top insulalor on the backstay should be
approximately 300 mm lrom the mast and the bottom insulator should be at eye
level above the deck. The distance between insulators should be greater than 10
metres and less than 35 mehes. A whip antenna is generally used on small to
medium sized power vessels. There are dlllerent length whips to suit the vessel
length.
Transceiver and tuner mounting
Select a suitable position in the vessel to mount the transceiver, It should be a
posifion that is out or the weather and easily accessible to the operator, whilst as
close as practical to the 13.8V no partner source. Mount the transceiver to a solid
fixing point using the mounting cradle. Make sure there is sufficient space at the
rear of the transceiver to connect the power and antenna cables.
The antenna tuner should be mourned as close to the antenna teed point as
possible. In metal vessels the length oi the leader tram the antenna tuner to the
feed-through insulator, inside the vessel. should be kept less than 1 metre.
The antenna teed cable should be a suitable high voltage cable. Care should be
taken to avoid sharp points when terminating the cable m prevent oorona
discharges.
The interconnect cable supplied with the antenna tuner should be routed away trom
other cables back to the transceiver and connected as indicated in the diagram
overleaf.
228 oi 237 m
0 HF SSB TRANSCEIVER
Ground (earth; system
The ground (earth) system is a key part or the overall antenna system and
consequently the system operation. An inadequate ground system Is the primary
cause or poor performance and tunlng problems. There is little point in installing
the antenna unless a good ground system can be provided.
Metal hulled vessels provide an almost periect ground. The tuner ground terminal
should be connected directly to the hull using the shortest possible ground strap.
The point of connection to the hull should be prepared so that it Is tree ot palm and
mst to ensure a good contact area with minimum electrical resistance.
Wooden or fiberglass vessels present more or a problem to ground. Ideally the
vessel should be fitted with an exlemal copper ground sheet. connected to the
interior ot the vessel by suitable stud or an earth plate ("is- plate Barrett PIN
BCA91700)
II the vessel is yet to be conslrucled, then in the case of fibreglass vessels 3 thin
oopper sheet with an area or not less than 4 square metres should be moulded Into
the hull dun'ng lamination, A suitable heavy strap should be connected to the sheet
and left. tree tor sanh connection.
Should neither of these methods be available it will be necessary to bond as many
large metallic obiects, such as the engine and propeller shalt, together to form a
ground.
Whichever method Is used the ground run trom the ground system to the antenna
tuner should be as short as possible and use copper strap at least 50mm wide
(wider if available). Consideration must always be given to the problem ot
electrolysis. Severe structuml damage may occur it electrolysis Is present.
Corrosion
All connections in marine situations are subject to corrosion and oxidation. To
mlnlmlse this all joints should be cleaned and have slIlcon grease applied before
assembly. Under severe conditions ioints should be protected with selt vulcenlslng
rubber tape.
===—== 229 ot 237
ARRETT HF SSB TRANSCE‘VE
Connection defialls - 2050 hanueiver and 911 automatic antenna tuner In a
marine installation
mu Q
o s“ unbound-2 nnbennl Inner
Emmi GPS neeiver option
Featflhm hsulamr PIN BCAQ1701
(n requlm)
o Antenna
0 Heavy mlyiuse A header PIN moon
Comew'on for mm 131 unil option
Auxililry summer
Coaxiallwnm cable P/N swoon
a men we! able wwlled
wilh wansceiver
a 2050 lmnweiverbody
Extenfion speaker suppiied standard
mm 2050 iflnwewar
Omhnd s or 10 mm extenuon able
with commas PIN swoon/40
Miunptnne
eeeeee
230 of 237
BARRETT 2050 HF SSB TRANSCElVER
Electrical checkout
After mechanical installaiion is complete select the highest frequency to be used on
the transceiver, A directional watt»meter such as a Bird Model 43 should be
inserted In the coaxial transmission line between the transceiver and the timer. The
tune mode on the transceiver is then energised (refer to the transoe'wer user
manual). Upon application or RF energy. the tuner should start to tune, Indicated
by the 'c|attering' or the tuner relays. Alter a low seconds the relay noise will cease.
The transceiver should indicate a sucoesslul tune and the watt-meter reflected
power should Indimte a low value consistent with a VSWR or better than 2:1. lithe
cover of the tuner is removed the PCB mounted ‘tuned' LED should be Illumlnated.
Now select the lowest desired frequency on the transceiver and repeat the above
procedure. The result should be the same. except that the tune cycle may take
somewhat longer, It the above procedure does not give the results as indimted
check mat lhe antenna length and connections are correct and recheck all ground
(earth) connections,
Note:- When received, the Barrett 911 automatic antenna tuner memory
system will usually not have any pre-stored tuning Information appropriate to
your installation. To allow the 911 to 'Iearn' Its tuning Information simply
proceed from one channel to the next allowing the normal time cycle to take
place. Each successful time Is 'memorlsed' so that when that channel Is re-
selected the tuner will almost Instantaneously retuiie to that frequency.
= 231 01237
HF SSE TRANSCEIVER
Con nectors
Note:- All connectors below viewed looking at the rear of the transceiver
GPS connector
1 NMEA - -12 VDC data Input NMEA 0183 iormat
2 +5V +5 VDC supply max 75mA
3 NMEA + $12 VDC data input NMEA 0183 tormel
4 Ground Ground UV
5 1PPS 1PF'S liming pulse TTL level from GPS
6 GPS RX GPS TTL data input
Fan connector Automatic antenna
@ my
0 |oo
1 +133ch 1 Tune inmales tune 911,
preamp active low 910
2 Fan control - active low 2 4 13.8VDC (Interrupled for 910
tune initiate)
3 Tuned -tune successful low
going pulse.
4 Ground OV
Power connector
+13.8VDC input $13.8 VDC
-1 3.8 VDC/Ground 1345VDC/Ground
1 Fan control out Active low W
2 Speaker oul External speaker Nov
3 MC
4 WC
5 WC
A1
A2
232 01237 E
RRET
SCEIVER
OHF SSBT
Auxiliary connector (25 pin female ”D” connector on rear panel)
I“ Descrlptlon our-notion Level
“V
7 RS—ZBZ Gnd RS-232 Ground UV
m —n.oww
Aux 1 Scan siep input irorn sxl‘emal modem Active low ov
‘ 11 Balanoed Tx audio lnpui (with pin 24) 500 n mama-rile...
‘ 12 Balanwd Rx audio ourpul (wiin pin 25) em: n Adsmmoslsm
1 Ground ov
14 Aux dig am 0 Linear LPF select Active km W
Aux dig oui 1 Linear LPF sated Acme low uv
Aux our 2 Linear LPF eeieei Acme low ov
Aux dig on] 4 Active low nv
Linear LPF select iAudio mule Active low nv
20 Fuiure use Aciiva low ov
PTT cull Receiver Cross Mine Active low ov
new Outpui lo power auxiliary equrpmeni 133V @ 2 Amp
Bal Tx Audio in Balanced Tx audio inpui (wnn pin 11) 500 n mammals-n
i-
Bal. Rx Audio Oui Balanced Rx audio ouipul (wilh pin 12) 600 n «an remain
Neie 1:- Pin 18 and Pin (9 — Funeiien depends on programmlngt» li Linear
Amplifier selected in lio configuration ihese lines are programmed lo eonirol lire
linear LPF selection oi 2075 linear amplifiers. Otherwise Pin is becomes lire seieail
alarm ouipui pin and pin 19 ioilows me audio mule condition,
15
17
Note 2:- Balanced Rx audlo out on Pin 25 and Pin 12 can be unmuted oriollowthe
audio mute depending on the configuration in the protected menu "1/0 section"
233 of 237
BARRETT 0 HF SSB TRANSCElV
Overview of HF operation
HF (High Frequency) is the radio spectrum with frequencies between 1.6 and
SOMHZ. Within this radio spectrum an efficient form of transmitter modulation, SSB
(sugle Side Band), is used. This, combined with the use of the ionosphere - a layer
of ionisafion gases that resides between 100 and 700m above the earth's surface.
DIOVides efficient, cost effective communimtions over short. medium and long
distances - without the need for expensive re-ttansmlsslon devices, such as the
VHF or UHF repeaters or satellites. all of which have on going operational costs
and a reliance on a physical infrastructure.
In many remote areas. HF/SSB is the only form of wnmunicallon possible.
HF propagation
When HF/SSB radio waves are generated by the transceiver there are usually two
components:-
- The ground-wave. which travels directly from the transmitting antenna to the
receiving antenna following the contours of the earth. ‘
- The sky-wave, which travels upward and at an angle from the antenna, until
it reaches the ionosphere (an lenised layer high above the earth's surface).
is refracted back down to earth, to the receiving antenna.
Generally speaking, ground-wave is used to communicate over shortendistanoes
usually less Main 50km. Because ground-wave follows the contours of the earth, it
Is affected by the type of terrain it passes over. Ground wave Is rapidly reduced in
level when it passes over heavily forested areas or mountainous terrain,
Sky-wave is used to communicate reliably over medium to long distances up to
3,000km. Whilst the nature of sky-wave propagation means it is not affected by the
type of terrain as in ground waves it is affected by factors involving the ionosphere
as descrlbed below,
234 of 237 ===
BARRETT 2050 HF SSB TRANSCEIVER
Radio wave propagation illustrated
The following Illustratlons show the characteristics ol groundmave and sky-wave
propagation during day and night time. In each illustratlon the height of the
ionosphere above the ground is shown.
In both Illustrations Station A communicates with Stations B, C and D. Propagation
from Station A to B is by groundwave The diagrams illustrate that the ground
wave is not altected by the time or day and the helght oi the ionosphere above the
ground.
Propagation from Station A to C and D, however, is by sky-wave and as the
diagrams illustrate the sky wave ls significantly affected by the time at day and the
height or the ionosphere above the ground.
Under each diagram there are recommended working frequencies listed. Please
note that these will vary awarding to time oi year and other factors. They are
intended only as a guide and are subject to change.
Day
|0NOSPHERE
EARTH
The sun is higher, the ionosphere ls lilglier, the best frequency to use is
higher
A to B - Possible optimum working frequency is 3 MHZ
A to c - Possible optimum working lrequsncy is between 7 - 9 MHz
A to D - Possible optimum working irequsney is between 13-15 MHZ
= 235 01237
BARRETT 2050 HF SSB TRANSCEiVER
thm
EARTH
The sun is lower, Ionosphere Is lower, best frequency to use is lower
Ato a - Possible optimum working trequency is 3 MHz
A to C - Possible optimum working lrequency is between 5 - 7 MHZ
A to D - Possible optimum working frequency Is between 9 -12 MHz
Factors which affect HFISSB communications
There are a number ol different factors which will alfect the success at your
communications Via HFISSB radio. These are outlined below:-
Frequency selection
Frequency selection is perhaps the most important [actor that will determlne the
success of your HFlSSB communications.
Generally speaking the greater the distance over which you want to ccmmunimte,
the higher the frequency you should use
Beacon call, a Selcall (selective call) tunction built into the Barrett 950 transceiver,
makes lindlng the correct frequency to use easy. Beacon call is based on the
network transceivers all having a selection of lrequencies that will accommodate
most ionospheric conditions. When in standby the network transceivers scan these
frequencies waiting for a call (Selcall or beacon call) from another tmnsoeiver. The
transceiver wishing to check for the best frequency tc operate on sends a Beacon
Call to the station he wishes to contact. |' his call to the other station is successful
he will hear a revertive call from the station he ls calling, indicating the channel he
selected was suitable for the ionospheric conditions prevailing. It he dces not hear
this revertive call or It Is very weak, he tries on another channel until a revertive call
of satisfactory signal strength Is heard.
236 0! 237 _=
BARRET
OHFS
TRANSCEIVER
(Refer to Selcall (selective call) section of this manual for full details on Beacon call
operation.)
Time or day
As a rule, the higher the sun, the higher the frequency that should be used. This
means that you will generally use a low frequency to communicate early morning,
late aflemcon and evening, but you will use a higher frequency to cover the same
distance during times when the sun is high in the sky (e.g. midday). You will need
to observe the above rule carefully if your transceiver has a limited number of
frequencies programmed into it, as you may only be able to communicate
effectively at certain times of the day.
Weather Conditions
Certain weather conditions will also affect HFISSB communications. Stormy
conditions will increase the background noise as a result of 'statlc‘ caused by
lightning. This background noise could rise to a level that will blank out the signals
you are trying to receive.
Man-made electrical Interference
Interference oi an electrical nature can be caused by overhanging power lines. high
power generators, air-conditioners, thermostats, refrigerators and vehicle engines.
when in close proximity to your antenna. The result oisuch interference may cause
a continuous or intermittent increase in the level of background noise.
System configuration and Installation
The method In which your system Is configured and Installed will also affect the
success at your HF/SSB communications. Your choice of antenna system and
power supply is crifiml. Correct installation is also extremely important. An HF/SSB
transceiver is generall nstalled using different rules to those used to install VHF or
UHF transceivers. Failure to correctly install an HFISSB system will greafly anect
the communications quality you will obtain. Refer to the installation section of this
manual for details.
Vour local Barrett representative will be able to assist with your system
configuration and/or installation.
Special note - HF communications compared with VHF or UHF short distance
communications
Communications on any HF/SSB transoelver will sound different to that on a VHF
(Very High Frequency) radio or UHF (Ultra High Frequency) radio or telephone
This is because ol the nature or HF propagation and the modulation methods used.
On HF/SSB transceivers there will always be background noise evident behind the
signal you are receiving and this will Increase when there is electrical interference
or thunderstorm activity In the area.
===_== 237 M237
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