[Johnson] Valiant problem

[James Liles]

Good evening Dutch:

This problem sounds a bit like it was worked on by several on this reflector 
before.  Don't remember if they resolved the problem or not.

These capacitors participate in the final tuned circuit and the mica was an 
appropriate choice because of their stability.  If you find a 330pf ceramic 
cap, be certain that it is a type 1, COG, NPO, or temperature compensating 
which are the only stable ceramic capacitors fit to participate in an 
analog/tuned circuit where significant voltage swings are the norm.  The 
capacity of the class 2 or 3 ceramic caps varies with voltage like a varicap 
and will result in harmonics and RF distortion.

Just a thought, will an air variable fit in the location allocated?  That 
design appears to be a high current configuration.

Do the 40 meter caps overheat like the 80 meter set?

Good luck and Kindest regards Jim K9AXN





Message: 1
Date: Wed, 14 Mar 2012 17:14:29 -0700 (PDT)
From: Dutch Maurer WB7DYW <wb7dyw at yahoo.com>
Subject: [Johnson] Valiant problum...
To: Johnson Mail list <Johnson at mailman.qth.net>
Message-ID:
<1331770469.34560.YahooMailClassic at web111706.mail.gq1.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1

My valiant has a problem with C-39 a,b,c,d (330Pf 500 volt silver mica) the 
original caps burned so I replaced them they burned also so I used 330Pf @? 
1Kv, they also get hot, now I have a 330Pf 15Kv doorknob, YUP ya guessed it 
it gets hot, rig loads to 150 watts at 330m, any suggestions??? Idling 
current is 60 Ma....

73's Dutch WB7DYW
CCA Member # AC99-00918

Success is not a place in time, it is an attitude!!!!!

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