Heathkit HW-12 - Page 47

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mount the unit on the floor, See Figures 4A
and 4B, The gimbal bracket should be mounted
in the desired location in the automobile, using
the #10 sheet metal screws, The starting holes
for these screws should be made with a 9/64"
drill, being careful not to drill into existing wir-
ing or instruments, Keep all Transceiver cables
clear of the automobile pedals and control
cables,
Any cables that have to go through the fire wall
will usually fit through existing grommets, If it
is necessary to make holes through a sheet metal
partition, a long tapered punch usually works
better than a drill, A drilled hole leaves sharp
edges which can cut the wires, When a punch is
driven through the metal, the sharp edge is rolled
back and a smooth hole will result,
Be sure to leave enough extra cable sothe Trans-
ceiver can be removed from the gimbal bracket
and operated, to permit adjusting the rear apron
controls,
Mount the antenna according to the manufactur-
er's instructions, Be sure to make a rood ground
omax “ Sv hall — tol wu
connection between the shield of the coax cable
and the car body at the antenna base, Low fre-
ae tee ASL an Um
quency antennas with loading coils must be care-
fully tuned, as a small change in antenna
length changes the SWR considerably, The fre-
quency range of whip antennas on 75 meters is
usually only about 25 ke; beyond this range
loading becomes difficult or impossible with-
out readjusting the antenna,
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bod
IMPORTANT NOTE: To make a loaded whip
antenna present a 50 Q load to match the coax
cable on 75 meters, a 1000 upf mica capacitor
must be connected between the base of the an-
tenna and ground, This can be done inside the
automobile body as shown in Figure 8A, or be-
tween the antenna and one of the mounting
screws, using two control solder lugs as shown
in Figure 8B. The necessary parts are supplied
with this kit, Connect a SWR bridge to the an-
tenna and make sure the SWR is below 1.5 to 1.
Power for operating the bridge may be obtained
by carrier output in the TUNE position of the
FUNCTION switch,
The FINAL TUNE knob will peak in the center
third of rotation with a properly matched antenna
Weld US SULALSUTS Walds We ay scenes at esse,
Do not use an antenna that will not tune through a
"peak" in TUNE.
ath Mo » Sneaker can he used for
utomobile, or a car radio
may be used,
mnect the cables and mount the Transceiver
in the gimbal bracket, Position as desired and
tighten the thumbnuts. "I
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190 0. MLE 1000 LF | |
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SOLDER LUGS
Figure 8B
Figure 8A