Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
----------------------------------------------------------------------
Doc -
Wow, not pretty! :-)
The original was a ceramic trimmer of 3 - 50 pF, with a single 27 pF 1
kV cap in series with it. This is the neutralization cap and so has to
handle the full plate voltage (700 VDC no load) plus peak RF voltage.
This must be a very early TR-3 (s/n <4000) to have the ceramic trimmer
in that position. Later units used a small air variable here, a
Hammarlund MAPC, 2.7 - 8.4 pF, with a 12.5 pF @ 2KV disc ceramic in
parallel. I suspect they had problems with that ceramic trimmer
breaking down (as did Collins in early 75S-1s) and changed to the air
variable. The same air variable and parallel cap was used throughout
the rest of the TR-3/4 series, so you can get one from just about any
parts unit.
If you can't find one, I may have one here somewhere. I'm not too well
organized after the move! Ya really shouldn't move after 25 years on
one house, especially if you're a pack rat......! :-)
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>
Halo.net wrote:
Garey,
You'll recognize the disk caps in the attached picture from the finals
plate circuit.. these are in bad shape & I can't lift any info from
them. I have a manual on order but no schematic on hand.. Can you
tell me off hand what the capacatance is and voltage rating? Thanks..
Doc WB6WAD
------------------------------------------------------------------------
----------------------------------------------------------------------
Submissions: [EMAIL PROTECTED]
Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body
Hopelessly Lost: [EMAIL PROTECTED] - help in body of message
Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net
----------------------------------------------------------------------
