Transmitter and Receiver Modifications for the FT-736 and Other
Rigs for Microsat Operation
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- Before you do any modification, call your rig's manufacturer
to see if they have a service bulletin for 1200 baud PSK and 9600
baud FSK modifications. Other sources for this information are
the various AMSAT nets, and the
AMSAT-BB discussion group on the
- In some Yaesu manuals the data in/out jack pins are listed in
reverse of what they actually are. The mini-stereo tip is the
received data (RD) and the ring is transmitted data (TD).
- My 9600 baud modifications are based on a bulletin by James
Miller, G3RUH. I expanded on this information based on my own
experimentation and from messages from other users.
- I received reports that R91 has been mounted in reverse on
some production runs, so that the discriminator must be tapped at
pin 10 on the RX module's FM scanner board. Yaesu assured me
this has never been the case. Although Pin 10, which comes
directly from the discriminator, reportedly works for DSP-2232
users, the recommended tap is on R91's side opposite the
discriminator, as discussed above.
- Pin-outs for the CAT port was in error in some FT-736R
manuals and in an old Yaesu "Application Note". The correct
Pin 1 Ground
Pin 2 Serial Data In
Pin 3 Radio Port Busy
Pin 4 Serial Data Out
Pin 5 No Connection
Pin 6 13.8 volts
Note that the pins are not numbered sequentially:
(rear view of male plug)
- This method of setting deviation was suggested by James
- PBLOGNEW.EXE by Patrick, F1TFQ was used to statistically
analyze my throughput from my pb.log files for UO-22, KO-23 and
KO-25. This file was downloaded from KO-23.
- Modification and performance evaluation by Manfred, XQ2FOD.
He can be contacted on KO-23 and KO-25.
Article and notes by Howard Sodja, W6SHP. HTML conversion by
and feedback to KB5MU.