YAESU FT480R VARACTOR DRIVE MOD FOR 9600FSK AND 1200PSK
        -------------------------------------------------------
                     by Dave Hulatt G4WFQ
                     --------------------

For those of you who owning an FT480R and would like to be able to modulate
the varactor directly heres a simple mod. It will give you a much better
uplink on Fo20, Lusat and Pacsat. You will also be able to input 9600bauds
directly to the same point and be able to work UoSaT-3 aswell.


First of all make up the following simple small circuit.
                                     8vTx
                                     :
                     8vTx            :--------------
                     :         ------:------        :
                    47k       :      7     6:---:----------(to fm mod post)
                     :        :    ca3140   :   :   :
     Txa in----------.--------:-3           :   : ----- 100n
                     :        :       4   2 :   : -----
                    10k       :-------:---:--   :   :
                     :                :   :-----:   :
                     :                :             :
                     :                :-------------:
                     :                :
      Txagnd-------------------------------



Note pin 2 is linked to pin 6 on the ca3140.



Locate the so called FM modulator which is XM01, you will find that there
is a connector post nearby which you can apply the output from the above
circuit to. Then connect 8vTx from the post which is also nearby.
Keep the leads as short as possible. You will have to connect a switch in
the 8vtx line so that you can use the mic skt as normal.


Some component changes are needed to the modems.
G3RUH 9600 Modem :- change C34 for 470n or place in series.

G3RUH Psk Modem :- Remove R5, change R3 for 50k pot, change c9 to 100nf.

Set output of Psk modem for 500mv.

Nb. This will pull your radio off frequency slighly about 5 khz. Allow
for this simply by adding 5khz to your read-out.

eof