Visit our newest sister site!
Hundreds of free aircraft flight manuals
Civilian • Historical • Military • Declassified • FREE!

TUCoPS :: Radio :: ic275_1.txt

Icom IC275/271 mods

(2) To gain access to ACC1 you must remove the PLL PCB that it is
mounted on. With the board removed I soldered the extension wire to
the underside of the board taking care not to short out any
surrounding tracks. The whole exercise took about 30 minutes.
You will probably need more audio level from you PSK modem (see
changes recommended by G3RUH in his FT-736 discussion). You can then
use the pot, F151, in the IC275H to set the TX modulation level.
Results from making this change have been outstanding with many less
retries on the uplink than previously. The waveform being applied to
the Varicap diode is now identical to the output from the modem.
Performance via LUSAT and PACSAT digipeaters have been equally
pleasing. EXTRA hint: Use DWAIT=0 RESPTIME=0 and start TXDELAY=100 ms
and reduce to as low as possible for your radio - I use 30 ms.
A similar change could be performed on the ICOM IC271 by wiring to J12
on the Main Board. J12 is normally unused in Australian IC271's.
Since the above article referred to G3RUH's FT-736 discussion, I sent a
message to James Miller G3RUH on FO20 and asked him to repost it on the
bird. I had lost the copy I downloaded since I did not anticipate any need
for it.

TUCoPS is optimized to look best in Firefox® on a widescreen monitor (1440x900 or better).
Site design & layout copyright © 1986-2015 AOH