[Heathkit] DX-100B Capacitor Question

[Glen Zook]

There were 3 capacitors in the driver circuit that were changed in the DX-100B from the original DX-100.  The changed values were to improve drive on the 10-meter band.
 
Glen, K9STH


Website:  http://k9sth.com


________________________________
 From: L L bahr <pulsarxp at embarqmail.com>
To: Bruce Spacer <wb8vcm at hotmail.com> 
Cc: heathkit at mailman.qth.net 
Sent: Wednesday, April 11, 2012 8:58 PM
Subject: Re: [Heathkit] DX-100B Capacitor Question
 

Bruce,

I had a conversation with Garey Barrell, K4OAH about this and he pointed out there is no 68 pf Silver Mica between the driver and the final tubes.  That coupling cap should be a .001 and not 68.  There is a 47pf cap between the 12BY7 and the 5763 tube.  So are you talking about something else, or do you have the wrong capacitor where there should be a .001 ???  (I'm talking about the blocking capacitors). After the .001 blocking cap you have a pi-network feeding the grids of the 6146 tubes.  There is a variable cap on the input side of the filter and a fixed 47pf cap hanging from the filter to ground on the output side of this pi filter feeding the 6146 grids.  There should be no 68 pf cap of any kind in the entire DX-100. 

Thanks, Garey.

Lee, w0vt



I am rebuilding a DX-100B and saw a posting that it would be a good idea to replace the 68 pF mica between the driver and final.

The existing capacitor is a molded mica Sangamo.  It has no color codes, but on one side is stamped "68 5%".  

On the other side, it is stamped "2000 VW" (not WV).  It is arranged like a 6 dot format, and when you hold it with the arrow pointing right, the digit "2" is molded into the upper middle dot.

Is this a 2000V part ?  A quick check of the Mouser site shows the typically available CDE micas (CDV19) are only rated up to 1000V.  Any suggestions for a replacement ?