It's two days before Christmas, you
try to tune up your HF as a quick
check before you head off into the horizon
and it doesn't work. What do
you do? After checking coax, cables. take the
lid off the transceiver and
see if any transistors on the tuning board
(Option AD) are hot while the
antenna is being tuned. The four power
transistors often fail making
tuning difficult. If after checking these the
antenna still wont tune,
your next step is to take over the kitchen table and
pull your antenna
to bits.
Remove the four hex head bolts
holding the base on.
Seperate the base, taking care not to break the
O-ring.
Step 2. Remove the four screws
holding the earth plate on.
The centre screw is adjusted so it just makes
contact with
the base on re-assembly.
Step 3. Undo the screws holding the
coax and control cable connectors.
Disconnect the wiring from the PCB. Mark
the orientation with a texta
or similar. If you hook them up wrong on
re-assembly you destroy the
circuitry and stepper motor. Remove
the connectors from the antenna.
Remove the screw holding the ground wire by
placing a long screwdriver
through one of the holes where the connectors used
to be.
Be careful when removing connectors or this may happen.....
Step 5. Tap the base of the antenna
on the ground to loosen the internals
and slide out the worm drive
mechanism.
Step 6. Unsolder the red wire from the PCB.Remove the insulation tape
holding the wire in place. Undo the two
brass bolts holding the tuning
coil to the motor and remove.You may have a different
antenna to what
is pictured, see bottom of page for dissassembly
details.
The problem with this antenna is
that the solder has come undone at this
point. Other problems that may be
encountered are broken plastic tube,
particularly on these clear tube models
and the top cap unscrews.
Unwind the tube from the worm
drive, taking care not to lose the small
brass button. Apply a smear of
grease to the worm drive after removing
any old dried grease. Carefully clean
any carbon off the wire spring
contacts with contact cleaner and a soft
brush. Use a brush with a long
handle to clean inside the tuning coil. Check
the screw that holds the
white cap on the top of the tuning coil is secure.
Using the long brush
again clean inside the antenna case where the tuning
coil plugs into the
top of the antenna.
You may find you have the later
style internals. If so unsolder the red
wire from the PCB as metioned, and
remove the screw holding the black
flylead to the tuning coil before
removing the two brass bolts.
Re-assemble antenna taking care
when re-attaching the tuning assembly
to the motor that the small brass
button is aligned properly in the
tube. Be careful not to overtighten the
brass bolts, they break easily.
Remember to replace any insulation tape that
was removed. When inserting
the assembly into the case give it a slight
wiggle to seat the connector
at the top of the coil. Use silastic to seal
under the coax and control
cable connectors.
Hopefully when re-installed on the vehicle it works.