[Johnson] Start of New Year

[Evan Rolek via Johnson]

Failures with coax jumpers are rare in my opinion. BUT there was an experience I had with a jumper I made up, it was about 40 years ago, and it failed last year.  It showed no leakage between the center conductor and outer braid.  Outer braid conducted from one connector to the other, same for the center conductor.  Threads and center pins were not corroded but I cleaned them, applied DeOxit, etc. etc. all to no avail.  But, with RF power applied, it caused distortion in my audio though no indications on my SWR meter that anything was wrong.  I did many tests, substitutions, etc. to confirm that it was indeed the culprit.  This is just one of many things to check...


73,



Evan, K9SQG


-----Original Message-----
From: Bill Cromwell <wrcromwell at gmail.com>
To: johnson <johnson at mailman.qth.net>
Sent: Thu, Jan 1, 2015 1:15 pm
Subject: Re: [Johnson] Start of New Year


Hi David,

I don't know what 'zsac' is but the first thing I would be looking for 
(if I understand correctly what you are saying) is defective coax jumper 
cable somewhere outside of the transmitter. I have had that happen in my 
station a couple of times. It's the easiest part to check. Good luck 
with repair project.

Happy New Year

73,

Bill  KU8H


On 01/01/2015 10:24 AM, David C. Hallam wrote:
>
>
> Yes the grid current does vary when I increase the drive.  In the CW 
> position  I get about 600 mA of plate current.  With the PA tuning I 
> can dip to to about 40 mA with no indication of output on my monitor 
> scope.  All of this leads me to believe the problem lies in the PA 
> tuning/loading circuit.  In the SSB position the zsac does not change 
> from about 220 mA when I apply audio drive from the exciter.
>
> David
> KW4DH
>

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