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</head><body bgcolor="#FFFFFF" text="#000000">Hi Keith,<br>
<br>
You're very thorough - quite a virtue in its own right.<br>
<br>
I have to admit to being lazy. I connect the transmitter to a 50 ohm
dummy load and measure the voltage across the load with my scope. I just
use (Vp-p^2)/400 as the power output and figure it's close enough.<br>
<br>
73 Bruce<br>
<br>
<br>
<br>
<span>Keith Wilson wrote on 4/15/2019 4:20 PM:</span><br>
<blockquote type="cite"
cite="mid:CABs1b9WtcJNPdmBOLiJJYrYTVjE9cQ=WNr7rQiJtWJsVkCH4Xw@mail.gmail.com">
<div dir="ltr">Gentlemen - an update to my power output measurements
on the 20m Raspberry Pi board:<div>The (impedance unknown, alligator
clips to BNC) cable between the board and the dummy load was affecting
the dummy load impedance. The SWR was showing about 1.55 with a
RigExpert!</div><div>I tried an alternate method using the Flex
panadapter and sampling with an Alpha Delta coax switch, attenuation
about 90 dB. The WSPR board signal was down about 15 dB vs a 5 W
signal. So that gives an output of 22 dBm which looks pretty good. I
also tried a 0.5 Watt signal and the Flex panadapter looked pretty
accurate i.e. down 9-10 dB from the 5 W signal. I think this is a
better test!</div><div>Keith - KE4TH</div></div>
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