Saving the Kenwood TR-751/TR-851 transceiver from the electronic scrap yard

The very first VHF transceiver I bought when I got my HAM license was the Kenwood TR-751E.
It was at the time in the early 90's one of the best VHF transceivers on the market.
After a while the very well-known potentiometer problem started to appear.
At the time there was still spare parts to be found, today it is a different story.

I came across two stations, one TR-751E and also a TR-851E for as I saw it, a very reasonable price.
The low price was as I suspected due to the faulty potentiometers, but that could easily be fixed, right?
NO...! I Searched the Internet for several hours looking for spare parts and I ended up with nothing.
The problem is to find a double potentiometer with the shaft diameters and lengths that are used in
the TR-751/851 models.

There are two potentiometers that could fit with some modification.
RV50303522 for the Vol./Sql./Pwr.
RV20303523 for the RIT/RF Gain.
Unfortunately I could not find a supplier who would ship to Sweden :(
On the other hand the previous owner had done Vol/Sql replacement which would have been much harder to repair.

So what to do? Could the faulty RIT potentiometer be repaired or modified somehow?
I came up with an idea to reuse the shafts and use standard trimmer potentiometers.

This is how I did it....


The radio was opened up and the front panel removed.
Circled in the picture above you can see the two potentiometers. The one to the right is the faulty
RIT/RF Gain potentiometer.
While I was at it, I also replace one broken LCD lamp. It was a lot of work just to replace a lamp.



Potentiometer removed from front panel.

Dismantling the potentiometer I realized that it was beyond repair.



I ordered two 10k potentiometers from my favourite electronics supplier.
Together with the original shafts and a piece of an experimental board I had the parts to build
a new functional double shaft potentiometer that would fit inside my TR-751E.



The RF gain potentiometer soldered to the experimental board.



RF gain section completed with outer shaft mounted, and board cut to fit inside the radio.
A drop of glue was added to keep things in place before assembling it together with the RIT shaft.



Rit potentiometer mounted and aligned with the shaft.



The new potentiometer is soldered to the original board with wires about 5cm long so that the board
could be stowed away to the side.



RIT/RF Gain potentiometer mounted in place. Nice fit!

Works well. Mission accomplished. Radio saved from the electronic scrap yard!