[Elecraft] Power Readout Discrepency

Sun May 18 19:06:59 2003

Parker
There's another thing you can do to eliminate having the
WM-2 in line all the time.  Write down what power you have to
request by band to get 5w out on the WM-2 into a matched load.
Then put the WM-2 away.
73, Bob N6WG

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Parker Buckley
Sent: Sunday, May 18, 2003 2:29 PM
To: Ron D'Eau Claire; [email protected]; Don Wilhelm
Subject: Re: [Elecraft] Power Readout Discrepency

Don and Ron, here's some better data.  I had made my
previous comparisons with the dummy load at the far end of
an internally bypassed Palstar antenna tuner, a coax switch,
a homebrew tuner-tuner, and the Diamond wattmeter.  Hard to
say what all that does to the poor K2 trying to push a few
watts through it.  With the dummy load right on the back of
a WM-2 wattmeter and a short piece of coax from the rig
straight to the wattmeter, shown below is the displayed
power on the K2 to get 10 watts on the WM-2.  I get very
different values now, and for the most part they are within
10%!  Sometimes I have to do this to myself.  Sorry to drag
everyone else through it.  :)

Here's the data from 160 to 10 meters for 10 watts on the
WM-2:

8.5, 9.4, 9.9, 9.9, 10.8, 10.8, 11.7, 12.2, 12.2

According to the WM-2, the Diamond wattmeter, the tuner
tuner, and the coax switch each provide an impedence bump
resulting in some reflected power.  Thankfully, the Palstar
tuner switching is not a problem.  I am about to eliminate a
few accesssories and/or rely on the WM-2 for power settings;
not the K2 display.  I think I've learned enough this time,
and will just go look for a QRP contact somewhere.  Thanks
for all your patience.

Parker WD8JOL

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