Amateur Radio

I have two amateur radio licences, one British and the other American: G4ICV issued in April 1979 and AB2GR issued in November 1999.

Reluctantly, I have to make a statement to protect myself in this age of the litigious world where some people call a lawyer to sue someone instead of accepting the consequences of their own actions. By making changes to your equipment in the way I describe, you do so at your own risk and only your own risk.

Modification to swap the RF power control and Squelch control on an ICOM IC735

I have hardly ever used the squelch control of my IC735 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.

board board

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.

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Modification to replace the green bulbs with white LEDs

Because the green bulbs were broken, I replaced the bulbs with white LEDs taken from a cheap eight LEDs torch (USA flashlight). I used emery cloth to roughen them so that the light is diffused. I managed to fit 2K7 resistors in series with the raw power in, where the bulbs were wired. The result is a nice white display instead of green.

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