Date : 900605/1310 Subject : TS-790 Mods. for 9.6kbps
TS-790 & 96-14 and CBBS operation currently used at my site.
Please refer to G3RUH's notification for FT736R for more detail. RX/TX mod suitability remains same as his notes.
TS-790 ; FM Direct from Discriminator
Detected and amplified/buffered FM direct from the receiver discriminator is
available from Pin-9 IC1 (Sub) or IC8 (Main).
I use IC1 (Sub) for reception.
TS-790 ; Direct varactor FM Modulation
Inject your TX audio at the cathode side of diode D81 with a 1K ohm resistor
in series. You can find D81 near Q73 in your IF UNIT diagram.
Misc ;
It takes a bit of hard work for very small and jungle PCB. Use tiny tools.
Carefully adjust TX audio level by VR1 of the modem, it's rather low.
You would probably need some local friend to do this adjustment, asking him
to tell you his TNC's DCD LED stays steady (no flicker).
de Kohjin Yamada, JR1EDE @ JR1EDE.11.JPN.AS
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