FAULTY VFO DIAL?

This post is to hopefully help beginners who are experiencing trouble with their dials! That could be your VFO, your volume knob, or virtually any other potentiometer or encoder that is not behaving itself (except optical encoders).

I noticed that my VFO dial on the ELAD FDM DUO was operating perfectly when turning clockwise but not anti-clockwise. It would either do nothing or it would tune down very erratically (sometimes even going up in frequency)! I also had a similar problem with my BELKA DX, so I dug out my can of contact cleaner and gave the dials a spray.

So what makes encoders go rogue? Well quite often it will be due to oxidisation on the contact surfaces or dirt and sometimes even moisture from condensation. The latter is especially true if your equipment is kept in a location which might be at risk of damp or moisture. My Belka DX for example spends a lot of its time in the glovebox of my car, where temperatures can quickly change from freezing cold to very hot. Some people have their shack in an out-house or a garage where humidity levels and temperatures can change significantly.

Whatever the reason, once a dial starts to malfunction, you need to do something about it - and it’s often extremely simple to get things back to normal. Buy a tin of Electrical Contact Cleaner and choose one which has a thin application-tube.

Remove sufficient panels on your radio to access the faulty switch and apply brief squirts of the contact cleaner to the switch’s moving parts. Some older switches will have their wafers open and visible, but most will be enclosed. Direct the spray to the part of the switch which will result in the cleaning fluid running down to the internal wafers as shown in the example below…

Spin the dial backwards and forwards (clockwise and anti-clockwise) to help spread the cleaning material across the contacts. If the dial also has a push function, be sure to work that too. It may require multiple applications depending on how bad things are.

Try not to get the spray all over your radio internals by covering open areas. And before operating your radio, allow time for the spray to evaporate and dry completely before powering up.

The encoders on both my radios now work perfectly and it only took a few minutes to complete the job.

73, Tom, M7MCQ.