Dave:
I think you need to look at the published work by Rich Measures, AG6K. See his
web page at
http://www.somis.org/QSK922.html
I implemented his QSK circuit and other mods in my SB-220 and it works fine.
He sells a kit for fast QSK switching. It uses a vacuum relay for RF output
and a reed relay for input RF switching, including an electronic switch for
bias control. He states that switching time is about 2 ms. He discusses the
TL922 as well. I did have to add another transistor stage to take the "AMP out"
signal from the Orion to trigger the switching circuit. It works beautifully.
Paul,
WQ1C
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