GROUND RADIO BULLETIN NO. 11 - july 27, 1949 COMMS. DEPT. L.A.D.
RPA-50 CV TRANSFORMERS
Since the advent of the RFA-50, there has been considerable failure of the sola filament transformer, item 23. Recently after a second failure in Guatemala, Fred Brough, Station Radio Mechanic, decided to dismantle the bad transformer in order to determine what happened. He found that sola had terminated the 25 ' ampere secondary with lugs that were entirely inadequate. The lugs were so small that the leads had to be cut down about 2/3 for the lugs to fit. In addition, the lugs were tightened against the bakelite plate which caused an eventual loosening and resultant heating. The lugs finally heated to a point that practically disintegrated the bakelite.
The effect was that the transformer no longer put out sufficient current for the 2000 T.
Fred*s remedy was very good and is a permanent cure. He removed the bakelite terminal board and cleaned up the internal leads. Next, he carefully spliced a piece of heavy stranded (#10 or better) wire to each lead. These splices were taped and painted. For this you can use shellac, cable paint or any suitable varnish. These leads were then terminated with standard 50 ampere lugs and attached to the terminals of the Jones strip. This change brings the internal wiring directly to the external Jones strip and eliminates two lugged contacts.
If you have one of these transformers that is bad, check the terminals inside the transformer and behind the bakelite plate. If it looks repairable, advise the DCS office.
These transformers are valued at approximately $50, and each one that can be reclaimed is that much saved.
