233D Transmitter Restoration Project
Here is the status and comments on my restoration of the PA output network.
The two large ceramic capacitors are a thing of beauty but unfortunately both are open. These guys are Cornell-Dubilier Electric Type 223-50, 0.002 mdf @10,000 Volts. They are constructed with cast aluminum end plates and each carries a name plate with serial numbers !!! I have serial numbers 4226 & 4123296. Do you think one was replaced much later? or why such a wide range in serial numbers???
I believe these are mica caps that are/were oil filled. The chassis was covered in the most vile oily gunge - maybe from the caps?? Anyway I used engine degreaser spray to do initial cleaning. Then removed the straps, two variable capacitors, two large tank coils, and one of the most interesting band-switches you ever want to see. These parts are all designed and fabricated by Collins and carry Collins nameplates with serial numbers.
We have to find out who the mechanical engineer was that designed this band switch.
I have taken the whole assembly apart and as I did so, I made lots of sketches and notes - even took about 25 digital photos so I can hopefully get it all reassembled again.
Today I worked on the band switch cleaning. Interestingly enough, under all the tarnish and crud, much of the RF conductors are tin plated copper strap. However, some was simply bare copper and others are silver plated. So the "before" photos show brown conductors while the "after" photos will show three different colors of metal.
The band-switch end pieces are cast aluminum painted gray. Holding it all together are 8 long hex posts all coated with corrosion crud. I cleaned them off with Phosphoric acid solution plus elbow grease and steel wool. I was surprised to find that the posts were nickel plated and really look spiffy now.
| May 8, 2013