[Johnson] Johnson Valiant doorknob cap

[Roy Morgan]

On Mar 11, 2008, at 8:27 PM, Joe Roth wrote:

>
>    I need to change my doorknob cap (C37) on my Valiant from the  
> current
>        500pf value to 1200pf (20Kv). Can someone recommend a source?

Joe,

Is this the final plate output coupling cap?  (The loading mica caps  
have been reported to give trouble, but I think this is not one of  
them.)  Did you find advice to replace this cap for 160 meter  
operation?  If so, I'd like to know more about it.  I have two Valiants.

Keeping in mind the advice about using 5KV caps, here are some sources:

http://www.af4k.com/capacitors.htm
He has a 500 PF doorknob cap, and two not yet measured.

The Presidents Page at Max Gain Systems lists 400  PF doorknob 7.5 kv  
caps for $6 each, but they may be N3300 or N5600 negative temperature  
coefficient types.
http://www.mgs4u.com/RF-Microwave/doorknob-capacitors.htm

Another place to look (with normal commercial prices) is RF Parts, Inc.

You should avoid the Robber Barons of Nebraska if you can, unless  
high prices don't bother you.

Roy
K1LKY