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Old August 22nd 08, 12:20 AM posted to rec.radio.amateur.boatanchors
afcsman afcsman is offline
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First recorded activity by RadioBanter: Jun 2007
Posts: 63
Default Johnson T-R switch receive port output levels?

Bob Spooner wrote:
I have acquired a Johnson T-R switch and during testing at 3.5+ MHz. and
about 100W into a good dummy load, with the receive port terminated with 51
ohms I'm seeing an initial level on the order of four volts peak before the
6BL7 shuts off and reduces the level. Is this normal? If not, what is
normal?
Thanks. 73, Bob AD3K


Now that you're reassured about receiver safety, please let me know
about your experiences with that Old-timey switch. Years ago, I used
a similar one with my Hallicrafters HT-37 and Drake 2B. I found that
the Xmtr's resonant tank circuit produced a null that went through the
T-R switch, and pulled down the 2B's sensitivity. I eventually
abandoned the Electronic switch for a relay.

Jerry, W9NPI