On Tue, 17 Feb 2009 08:25:16 -0800, Ross, NS7F wrote:

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:/...om/g/d5a7ff03/
t/3d5e036fddd024eb/d/355b6c8e64361096%3Fhl%3Den%26ie%3DUTF-8%26oe%3Dutf-8%
26q%3Dsabin%2Brelay%2Bband%2Bfilter%23355b6c8e6436 1096&ei=u-SaSdCSGIOU-
wGVlcGnBQ&sa=t&ct=res&cd=1&source=groups&usg=AFQjC NHG7VKozzInElLsIi0baYXpyphcAw
) 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

I've found that for RF below 2m, about any really will work within
reason. Bad relays to use are reed relays or any relays where the RF
leads are wrapped or parallel with large surfaces. Yaesu and Icom use
smaller DIP based relays just like the ones at radio shack. I would
simply calculate the current at the power level you need and use the
appropriate relay. I use "KP" relays all the time. even in the 2m band.