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That 17A485459 ballast tube sounds a lot like the 50A1s used in very old Zenith Trans-Oceanic tube radios. I believe those tubes also were gas-filled and used a length of iron wire, hence the "1" in the designation. It's the only vacuum tube I have ever heard of with just one element and no filament, except perhaps for the 0Z4, 0D3, etc. gas-filled regulator tubes that were the forerunners of today's Zener diodes.
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Jeff, WB8NHV
Collecting, restoring and enjoying vintage Zenith radios since 2002
Zenith. Gone, but not forgotten.
Last edited by Jeffhs; 05-07-2014 at 12:02 AM.
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