For my transverters here I went with ~30 dB atenuators. They
were very easy to make. I just bought some 300W dry dummy
loads from Vectronics. Then drilled a hole under the SO239
for BNC connector. Then inside I made a "pi" section with the
50 ohm load resistor as the input shunt, then a 1K 1/2W
resistor for the series section, and then 2 100 ohm 1/2W
resistors in parallel for the output shunt. So there was
almost no metal working involved, and the 300W loads were
ready made cases for the attenuators. When I measured them
tonight they came in very close to 32dB, just as the online
calculators say they should for the values I used.
I see that the Elecraft transverters can be driven with as
little as -20dBm. So I would reconfigure it for low level
drive and run more attenuation on the TX IF. However with 30
dB of attenuation you would obviously need to use split RX/TX
IF lines (something I would always do anyhow).
So with these attenuators I end up runing the TX IF output at
about 15-20W, well within ALC control / power stable range of
most any radio. And with 30dB it is next to impossible to
blast the transverter with distructive power, this is for
when (not if!) you accidently transmit full power into it
someday.
Duane
N9DG
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