[Johnson] Kit wiring instructions for Johnson Valiant

[Glen Zook]

Like many other things, there are two opinions on this and neither side is probably going to "give in"!  It has been years since I have owned a Ranger but I have worked on a number of the Johnson transmitters with the same basic VFO.  It has been my experience that putting the resistor outside of the compartment results in at least a longer period before the VFO stabilizes.

Now, I think that virtually everyone agrees that the 18K ohm resistor has to be replaced since it was grossly under-rated in terms of wattage.  

As I originally posted, the decision as to where to locate the resistor can only be made by the person doing the actual work.  Based on my experiences, I vote for retaining the inside position is desired.  However, there are definitely others who have had different apparent results.  As such, where to put the resistor is left as an exercise for the student!
 
Glen, K9STH

Website:  http://k9sth.com


________________________________
 From: Jerry K <w5kp at hughes.net>
To: Glen Zook <gzook at yahoo.com> 
Cc: "johnson at mailman.qth.net" <johnson at mailman.qth.net> 
Sent: Thursday, January 19, 2012 5:43 PM
Subject: Re: [Johnson] Kit wiring instructions for Johnson Valiant
 
Can't argue with that. Glenn. Haven't done any scientific experiments, but I have overhauled six over the past several years. I put the resistor outside on all of them, and have had excellent VFO stability from all six. Maybe I was just lucky, or maybe I was using more warmup time or something.
Jerry W5KP

On 1/19/2012 12:01 PM, Glen Zook wrote:
> There have been a number of experiments concerning the placement of this resistor.  Most have found that putting it outside of the VFO compartment actually affects the stability of the VFO in a negative manner.  The VFO temperature compensating capacitors were chosen to include the effect of the heating caused by the 18K ohm resistor.  When the resistor is put outside of the compartment it takes longer, in some situations never, for the temperature to reach the conditions at which the compensation capacitors were calibrated.
> 
> Of course, the choice of where to locate this resistor can only be made by the person doing the modification.  However, the previous experience of others should be considered.
> Glen, K9STH