Hello Jeff,

I collect TOs as well. Some time ago there was a collector who posed a similar
question on this forum. A long time and knowledgable member, Ludwell Sibley,
posted a response that is probably a better solution to the 50A1 problem. For
cosmetic purposes you may be able to find a 50A1 with an open filament to put in
the socket, but I personally wouldn't be concerned about that. This solution is
safer and will protect the other tubes that are getting rarer and more expensive
as well. You might want to consider putting a fuse under the chassis for
protection as well. Here's a link to a collector's website with some more
pictures and tips:

http://www.antiqueradio.org/transoceanics.htm

You may have to buy a whole wavemagnet with cable to replace the red line. Keep
looking on ebay. Like another writer said, these antennas from parted out TOs
show up there all the time. They usually aren't too expensive. "Basket Case"
model 600 TOs are fairly common at shows and hamfests as well and usually have
the antenna with line that can be used. They were made from around 1956 to
1962, even after the transistorized model 1000 came out, so they are around.
Keep looking you'll find one.

73, Mark, N3NBL

Here's the email:


Question:

I just picked up a Zenith A600 TO in VG shape. As fate would have it, the
50A1 ballast tube has open filaments! AES list the tube for a lot of money
and is out of stock. E-Bay prices are outrageous. Looks like the tube is
almost rare. >> My tube checkers don't list it nor do my tube manuals!

Does anyone have a solid state replacement or a tube they they are willing
to sell for a reasonable price or any suggestions? >> This TO is the last of
the Zenith tube TOs and is in very good condition. I would like to restore
it and return it to working condition.


Answer:

No sweat. Hang a 1000-ohm, 3-watt resistor (or two 470 ohm 2-watt in
series) across the filament pins, 2 and 7, of the 50A1 socket.

Then put a 9-volt zener (say, a 1N4739, 9.1 volts +/-10%, 1 watt) across the
9-volt filament string (i. e., across the final filter cap for the
filaments). In the case of my sets (I fixed two this way), the cathode of
the zener goes to pin 7 of the 3V4, and the anode to Pin 1 of the 1U5.

This does two things: you get better voltage regulation than the 50A1 ever
gave. Also, you are now utterly safe from the case where you have one of
the tubes out of the set, have the power turned on, so the final filter cap
gets charged to some voltage far above 9 V. Then you remember to plug the
missing tube in, and one of the tubes goes F*L*A*S*H . . . the 1L6, say.

This deal appeared in "Restoring the later Trans-Oceanics," "Radio Age," May
1995.

50A1, fuggedaboudit.

Lud

----- Original Message -----
From: Jeff Miller
To: antiquewirelessassociation@yahoogroups.com
Sent: Monday, September 24, 2007 5:58 AM
Subject: [AWA] WANTED: Zenith Trans-Oceanic "50A1" tube and "ladder line"


Hello all,

I just started restoring a 1959-1962 Zenith "Trans-Oceanic" (model
B600) and need a "50A1" current limiting tube. I just got the radio on
vacation up in Maine last week and discovered yesterday it was missing
this particular tube.

Does anyone have a good 50A1 tube available?

Also: Does anyone know where I can find the original style red "ladder
line" wire for the "Wave Magnet" antenna? This would be the red
plastic covered two-conductor stranded copper wire for the AM band
coverage. Mine was damaged by mice. There was a helpful suggestion on
how to work-around the wire issue last week (use zip cord), but I
would like to get the original style wire if possible. I'm starting to
think I will have to find a donor radio for this part.

Summary:

01) Type "50A1" tube.
02) Red "ladder line" wire for Wave Magnet.

Thank you,

Jeff
KC2OQG
kc2oqg@...





[Non-text portions of this message have been removed]