[ARC5] Getting GF Transmitter Going.

[David Stinson]

This information is drawn from the GF-11 manual.
There are differences in models; especially among the early sets.
But this should cover the GF-12 OK.
While the GF-12 is officially "28 volts," as Robert pointed-out,
the transmitter fils are wired for 12 volts.

I'm assuming you have checked the tubes, 
checked all the ground screws and connections 
to make sure they're not hi-Z,
de-Oxit on the metering jack contacts and etc.

You'll need:
---------------------
    12 VDC at about 4 Amps for fils and relay.

    200 Ohm  1/2 watt resistor.

    400-450 VDC with enough "juju" 
    to deliver 180 mils under load.

    For 80 meters- 75 pFd, 1000 VDC NP0 capacitor
    For 40 meters- 50 pFd, 1000 VDC NP0 capacitor

    Connector, likely available from Steve  swkb4dmf at windstream.net
        (awesome connector guy).

    12 VDC, 2PDT relay
-------------------------

Here's a diagram for running the transmitter "stand-alone:"

http://home.netcom.com/~arc5/gfru/GF-11.jpg

If you want the MCW tone to work, like for 
checking the modulator, unground pin 47.
Be sure to ground it in CW or Phone.
Pin 54 is sidetone out, if you want that.

Put the 75 or 50 pFd cap in series with the ANT lead in
order to match a 50-ohm antenna or coax.  
These values are not exact, but will get you close.
The Antenna Current meter will not show much using 
the method, but it's cheap and works.  If you want the
meter to swing, you'll need a 4:1 or 9:1 UNUN to 
step-up the output impedance.
    
Tune-up is tedious but once you get it set, you're done.
Pull the coil pack and check that all the connecting pins
are tight; they can "metal fatigue" on the back of the 
connection board and need to be re-soldered.
This happens on the back of the main connector, too.

Check that the antenna loading coil and contact wheel 
are clean.  If they are dirty, disassemble and clean with 
mineral spirits or acetone and a toolbrush.  
Allow to dry, polish with a paste silver polish,
clean with distilled water and reassemble, 
locking the screws down with orange or red nail polish.
Make sure you get all the cleaning/polishing residue 
washed-out or, in a few years, it will make you unhappy.

Set the tap wheel at half coil.  Plug in the coil pack
(you don't have to seat it completely; just make contact).
Tune the "ANTENNA COND" crank for max out.
Pull the coil pack and hold it with cover to the right.
Move the tap wheel two turns to the right.
Re-insert and retune.  If power goes down, pull the pack
and move the coil four turns to the left.  Go turn by turn,
which ever way increases power, retuning each time,
until you find max out.  If you want to monitor plate current,
you can plug a meter into the "RF AMP RF OSC" jack.

If you'd rather use a modern amplified microphone, 
replace the 200-Ohm current-limiting resistor 
with a DC blocking capacitor 
( 1 to 10 mFd at 16+ VDC. Not critical.  
Positive toward transmitter).

That's pretty much it.  Let us know how you do.

73 Dave AB5S