[Heathkit] SB-200 10M Power Output

[Carl]

Its been long established that a GG amplifier input network should be 
adjusted at power. Tube parameters are quite different between static 
(MFJ) and dynamic (operational) conditions.

While the MFJ, noise generator, etc will get you in the ballpark, final 
adjustment is done at full drive. As the frequency goes up the 
difference becomes more pronounced.

There are also published changes to the input networks to provide 
improved matching, especially on 10/15M. A Google should find them.

Also dont overlook the possibility of saturated or fractured cores. This 
happens from excessive heating due to mismatch and the only cure is to 
replace the coil or core with a known good one. Im fairly sure the cores 
are different material at least between the 5 band extremes.

Carl
KM1H


----- Original Message ----- 
From: <sbjohnston at aol.com>
To: <heathkit at mailman.qth.net>
Sent: Thursday, September 18, 2008 12:13 AM
Subject: Re: [Heathkit] SB-200 10M Power Output


>
> Not sure why Carl felt it necessary to attack the poor defenseless MFJ 
> antenna analyzer (a most useful device in my opinion)...
>
> If you can't reduce mismatch between the exciter and the amp, you 
> might benefit from a change in the length of the cable connecting 
> them, or try an antenna tuner between them as an experiment.  You may 
> find that your rig has been reducing its output in response to the 
> reflected power coming back from the amp.
>
> Is the grid current in the right ballpark on the amp when driving it?
>
> Steve WD8DAS
>
> sbjohnston at aol.com
> http://www.wd8das.net/
> ---------------------------------------------------
> Radio is your best entertainment value.
> ---------------------------------------------------
>
>
>
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>