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Author Topic: Harvey Wells TBS-50C  (Read 4205 times)
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KE5YTV
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« on: April 03, 2011, 05:52:43 PM »

Does anyone have an easy preamp idea for a TBS-50? I would like to use a crystal mic rather than a carbon.

Thnx, Mike
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Mike
KE5YTV  Dallas, TX
"The longest trip begins with a stop at the ATM."
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« Reply #1 on: April 03, 2011, 06:45:55 PM »

Mike,

The preamp built in as part of the TBS-50D is pretty simple.  You might consider just building in this simple 3 tube (2 X 6AU6 plus a 12AU7) into your TBS-50C case.  If you don't have the manual with the variants it is on the edebris reflector.
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« Reply #2 on: April 05, 2011, 10:35:14 AM »

That sounds like too many tubes to drive 6L6's, as it doesnt require 2 pentodes to tickle a 12AU7. One dual triode or a triode-pentode should do it.

HW probably wanted to be sure there was sufficient gain for the various cheap mobile and other hand mikes. I had a D model mobile but forget what mike I used but it was certainly something low end Grin

Carl
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kg8lb
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« Reply #3 on: April 05, 2011, 01:51:58 PM »

Mike,

The preamp built in as part of the TBS-50D is pretty simple.  You might consider just building in this simple 3 tube (2 X 6AU6 plus a 12AU7) into your TBS-50C case.  If you don't have the manual with the variants it is on the edebris reflector.

  Yes, 2 6au6 and a 12au7 are exactly what HW used in the "D" variant.
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KE5YTV
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« Reply #4 on: April 05, 2011, 02:09:52 PM »

Thanks for the ideas and the help.

Mike
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Mike
KE5YTV  Dallas, TX
"The longest trip begins with a stop at the ATM."
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« Reply #5 on: April 05, 2011, 02:14:33 PM »

 You can probably get enough drive out of most mic preamps (try ebay) to tickle the grid on your driver tube with a little experimentation.
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« Reply #6 on: September 30, 2011, 08:59:05 PM »

That sounds like too many tubes to drive 6L6's, as it doesnt require 2 pentodes to tickle a 12AU7. One dual triode or a triode-pentode should do it.

    I was thinking the same thing until I realized the TBS-50D used them 6AU6's in triode connection. I was home sick yesterday, and foolishly bid on an Ebay TBS-50D. Dam if I won, so now I get to think of restoration of a really old transmitter. What the heck was I thinking?  Huh

Jim
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