More Fun With The Hickok 288X: Cleaning and Reassembling The Tuning Capacitor

I've tried a couple of methods of cleaning variable capacitors over the years.  Most recently, on the RF-2200, I just doused it with contact cleaner in situ because I was reluctant to remove it from the radio.

It's best if you can remove the capacitor from the radio to clean it, of course.  And with this one out, I wanted to try a new (to me) method of cleaning - run it through the dishwasher.

I ran it on a regular cycle, with no dishes in the washer, and set it to air dry.

It came out pretty good.  It really wasn't visibly dirty to start with.  As an aside, I've also dunked them in a weak solution of naval jelly and water (great for rusted/corroded capacitors), and I also read that simmering them in tomato sauce (!) is supposed to work well.  The acid from the tomatoes is the key.

While the tuning cap is being washed, I worked on cleaning up the hardware on the signal generator.  The nice acorn nuts on the panel are dirty and could use a good cleaning.

So I took my usual solution of Simple Green to them, followed by a polishing with Noxon.

They came out looking pretty good.

I also cleaned the control knobs while I had them off.

After the capacitor came out of the dishwasher, I put it in a toaster oven set on low (200 degrees F) for a couple of hours to make sure it was dry.

Then I relubed the bearings since all of the old lube was washed off.  It turns nice and smooth now.

Here's the tuning cap back in the Hickok 288x.

The results are good!  It now oscillates over 5 mc - all the way up to 90+ mc.  This is good.   It doesn't quite go up to 100 mhz, so I'll look at that.

The bad news is that the low end of frequencies drop out at the same point on each band - the exact frequency depends on what band it's switched to.  More troubleshooting to come.