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NEAR-Fest Official News and Information => Mister Mike's "Mishigoss" Board => Technical Stuff => Topic started by: W1RC on December 19, 2020, 07:27:24 AM

Title: ICOM IC-735 Modification to Swap the RF Power Control and Squelch Control
Post by: W1RC on December 19, 2020, 07:27:24 AM
This is a very useful modification for the classic 1980s ICOM IC-735 if you like to change the power output level more often than you use the squelch control.  Essentially the modification ?swaps? the controls from the stock configuration where the SQUELCH is the outer control on the VOLUME knob and the RF OUTPUT is one of the slider pots in the sub-panel. 

The easy-to-perform mod was written and posted by Ian G4ICV/AB2GR to his web site with a link posted to the FACEBOOK IC-735 group.  However several months later his site disappeared and this valuable mod along with it.  Fortunately ?The Wayback Machine? archives has it and I was able to recover it, reformat it and now it is posted here. 

Thanks, Ian, for your mod.


MrMike, W1RC

ICOM IC-735 Modification to Swap the RF Power Control and Squelch Control
by Ian, G4ICV/AB2GR

I have hardly ever used the squelch control of my IC-735 but I often want to change the RF power output. The tiny control for this is difficult to adjust with any precision and the panel is showing some wear where my finger unavoidably touches it while adjusting the power.

I heard about this modification but no details of how to implement it. I examined the circuit diagram and discovered that both of these functions are controlled by a 10K potentiometer, the wiper connected to the function, one end of the pot open ended and the other grounded. It's a simple matter to cut two wires and cross connect them. The two functions to swap are marked POC and SQLL on the circuit diagram, respectively the brown wire in J3-P7 and the white wire in J6-P9. These jacks and plugs are on the main circuit board which is accessed by removing the bottom cover.

In the first of these pictures, the locations of the two plugs are shown. Use the two IF crystal filters to orient the picture with the IC735. J3-P7 is the nine pin jack and plug and J6-P9 is the six pin jack and plug.

The second picture shows how I made the cross connections. Trace the brown wire from J3-P7 to where it appears in the bundle near J6-P9. I had to pull it to identify it because there is another brown wire in the bundle there. By pulling the brown wire it's possible to extend it out of the bundle. The white wire on J6-P9 is easy to snip with not much manipulation needed. Snip the brown wire close to the white wire nearby and cross connect them as shown. I slipped a piece of orange insulation taken from a heavier gauge wire on to the wires before soldering them together and then slid them to cover the solder joints.

And there you have it..