R4A s/n 6850G
This is one of the latest of the R-4A's. There were two versions, and some modifications during each version run. "Early" ones ran up to about s/n 3300 to 3500, "late" ones sometime after, and are s/n's up to about 7000 are known. The very late ones are close to the same as the R-4B. More info can be found at http://www.zerobeat.net/drakelist/r4asurvey.html
below & above chassis. Top has been cleaned by dry brushing the dust away & rubbing with bits of rag, then swabbing with naptha/mineral oil, a light mix that mostly evaporates but leaves a light film of oil to retard oxidation.
Front panel, no blemishes noted. When I was finishing up with it I realized that the dial was a little tight turning, would not spin with finger pressure. I found that there must have been some dried lube in the main shaft/metal gear bearing area. I flushed it out with alcohol and reassembled it. It's much freer now.
Top cover has a few small nicks and scrapes. Nothing major, probably not warranting a paint overspray. It has original Drake feet on the bottom cover, the rear ones are short, so it tilts up at a slight angle.
The receiver has been completely aligned and is operating well.
The 28.5 band position has a crystal for 28.0 to 28.5 coverage.
The xtal calibrator will not come any closer than about 200cycles to WWV at 10.0. It has a new xtal which must be a little off.
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This page last updated on 02/21/2003.