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Old February 17th 09, 04:25 PM posted to rec.radio.amateur.homebrew
Ross, NS7F Ross, NS7F is offline
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First recorded activity by RadioBanter: Apr 2007
Posts: 12
Default Transmitter filter relay switching?

This is with regards to a medium-power (~50W) CW transmitter that I am
building for 40, 20, 15, & 10m. I would like to use relays to switch
the output filters, but have no idea what kind of relay I will need.
Dr Sabin mentioned that a high-quality relay is required (http://
http://www.google.com/url?url=http:/...Ii0baYXpyphcAw
) but I have been unable to find anything specific. Could anybody
please direct me to a resource that would help me answer this
question? Thank you very much.

For reference, the transmitter is a redesign of the classic '60s
"inexpensive 75W transmitter", originally by Lew McCoy (I believe),
one version of which can be found at (http://www.mines.uidaho.edu/
~glowbugs/inexpensive75wattxmitter.pdf ). It is a simple crystal-
controlled 6AG7 followed by an 807 amplifier at 75W input (50W
output). The filters are from Ed Wetherhold's article- (available at
http://www.arrl.org/tis/info/pdf/9902044.pdf ) 7th order "Chebyshev
With Added Zero" to give better second harmonic attenuation.

Best regards,
Ross, NS7F