Title: Harvey Wells TBS-50C Post by: KE5YTV 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 Title: Re: Harvey Wells TBS-50C Post by: WQ9E 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. Title: Re: Harvey Wells TBS-50C Post by: KM1H 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 ;D Carl Title: Re: Harvey Wells TBS-50C Post by: kg8lb 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. Title: Re: Harvey Wells TBS-50C Post by: KE5YTV on April 05, 2011, 02:09:52 PM Thanks for the ideas and the help.
Mike Title: Re: Harvey Wells TBS-50C Post by: kg8lb 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.
Title: Re: Harvey Wells TBS-50C Post by: WD5JKO 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? ??? Jim JKO |