>.....
>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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