Tuesday, October 23, 2018

IC-28A Volume and Squelch

My first 2m mobile rig was the IC-28A.  With a healthy 25w output on high and a 5w output on low, it is compact and a good little radio.  I gave $20 at a hamfest and I still use it as my go-kit radio for events and the XYL's car.

The volume and squelch controls were getting pretty scratchy.  The volume finally gave up and wouldn't make contact with the wiper, which meant full volume!

Consulting the manual showed that Mouser had the parts in stock

Mouser #:688-RK097111202P
Mfr. #:RK097111202P
Desc.:Potentiometers Potentiometers Flat 25mm 10k


Mouser #:688-RK0971114D0B
Mfr. #:RK0971114D0B
Desc.:Potentiometers Potentiometers Flat 15mm 10k

What was not apparent at first was that the pin arrangement spacing on the volume control was not exactly the same.  This required some modification to the sub board.  A #61 drill bit in a manual push drill made short work of this small modification.  The potentiometer tabs were easily bent over to make contact with the original pads.


The other difference that had to be dealt with was the difference in the shafts.  The original was a splined shaft, these new pots have a D shaft.  Adapting the original knobs was reasonably easy.  Since they are plastic and have a bit of elasticity, they were drilled out with an interference fit.  They could then be pressed on the D shaft and still stay in place.

The next project for this radio will be to build a Lithium battery pack for it and make it so it can be mounted to my bicycle.

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