ICOM 735 mods
 

hi!
I made a few mods to my Good Ol' Icom 735 and it's now
called Icom 735 PRO, still going strong since late 1980.
A few I found on the internet, but the filter mods I
have not seen anywhere.

Here is a list of what I have done!

- unlock mod: transmit outside the amateur bands.
- change squelshpot for the rfgain slide: very
convenient in use
- change rf attenuator from -20dB -- -10dB: -20dB is
really too much
- check and modify PLL time constant: if you have a late
model, the mod is needed. It results in less spurious
signals.
- check the solderings for antenna and rx connector.
- replace the lower IF (455kHz) SSB-filter and add a
new 455kHz narrow CW-filter, 500Hz or 250Hz.

This last mod needs some skills in electronics, but
makes wonders to the receiver compared to the
barndoor-wide original filters. I use the big 455kHz
x-tal filters from Yeasu FT-1000. 2kHz SSB filter and
500Hz CW filter. They just fit in between the main board
and the front panel. If you don't like the narrow 2kHz
on SSB, you can use the 2.4kHz wide if you can find one.
2kHz is recommended for contest use in a any case...

I'd love to hear if you can add something to this list!

cheers,
cb

ps
I love these old more or less analog radios where it's
still poosible to make repairs at home and mods and
don't have to look for firmware upgrades. A radio is a
radio, not a computer :) (just changing the PA
transistors on my Very Old (1978) TR-7 to get it running
again)

pps
I also rebuilt my Old (mid eighties) Dentron GLA-1000B.
Not much left of the original construction. Added 160m,
changed the very expensive original tubes etc etc...400W
key down output on all bands from 160m to 10m including
WARC bands. Nice small package and cheap compared to
vfets, hi!