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[AMPS] Full QSK for the SB-200

To: <amps@contesting.com>
Subject: [AMPS] Full QSK for the SB-200
From: measures@vc.net (Rich Measures)
Date: Mon, 24 Aug 98 19:24:44 -0800
>.....
>Still playing with the idea of full QSK for the SB-200.  I ran across a
>circuit in the Hints and Kinks column in the April 82 QST.  The circuit is
>a simple design to switch the cathodes of the 572Bs on and off based upon
>the presence of RF.  The presence of RF grounds the filament winding and
>turns the tube on.  The absence of RF applies +125 volts to switch them
>off.  
>
>I'm thinking about combining this circuit with the fast T/R portion of the
>Rich Measures' circuit to give the SB-200 full QSK.  Additionally the grid
>bias circuit could be permanently grounded instead of running it through
>the T/R relay.
>
>Seems reasonable, although I'm not sure what impact it would have long-term
>on the 572Bs. I wonder if they are truly "instant on" 

yes

>to support this concept.
>
>Any thoughts?

RF activated bias switching produces rough sounding audio and generates 
more IMD.. 
>
-  later, Tom


Rich...

R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  


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