[VHFcontesting] 222MHz tube amplifier help - AM-456A/TRA-19

larry zm1267 at gmail.com
Sun Nov 22 21:33:41 EST 2015


   Hello all, I'm trying to resurrect this amplifier I found today at a local antique store. It appears to be for the 222MHz band, and uses a 4CX250 tube. It is currently missing several tubes in the Power Supply section (V101, V102, V103 which look to be the rectifier tubes, and V105 which I'm guessing is maybe the time delay), and I could not locate anything of value on the web as far as schematics go. I took a peek underneath the PS to see if it's been updated with diodes, but there isn't anything extra added. Plus, there are 4 wires connected to V101 - 2 coming from the transformer, and 2 leaving and connected to V102. It appears to have been modified for the Amateur frequencies already or was in the process of being done, and I'm hoping it's on 222. Would someone have any idea what tubes I could use in this old beast, or a conversion article or tips on upgrading old military power supplies to SS? The transformer has a 1500V secondary if that helps any.

It looks like I've found my winter project ;-)

Thanks for your help,
Larry
N1MIW


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