Richard and all,
If you look back to Lyle Johnson's reflector posting of April 6, you
will find the following: (plus other good information about setting up
data modes.
"In this case, the ALC meter display is acting as a "VU Meter" and is
being used to help you set the Tx audio path gain correctly. It is not
showing you how much you are over-driving the PA. This is why you can
set it up in Tx test mode, when you are not transmitting any RF at all. "
Additional information can be found in Rev D of the K3 user's manual on
page 32.
73,
Don W3FPR
Richard Ferch wrote:
Well, I'll be doggoned!
Thanks, Joe - I seem to recall reading that somewhere, but I hadn't really
taken it in, and I was still using the procedure that worked with my
previous radio.
If I set the K3's requested power to 100 watts, then with 0 bars ALC I get
IMD well below -30 dB, but with even 1 bar it rises to -26 dB, and gets
worse with more bars. At the same time, the average transmitted power rises
above 50 watts - clearly the peaks are getting into compression.
However, if I set the requested power to 50 watts, I can push the ALC right
up to 4 or 5 bars while the average transmitted power stays at 50 watts on a
two-tone signal and the IMD stays below -30 dB. That's a safer and easier
way to operate.
So now to remember: in modes like CW and RTTY set the requested power to
100w, but in PSK and other similar modes cut it back to 50w. I can probably
figure out a way for my digital-mode software to remember this for me and do
it by software control.
Actually, I think I'll set it to some other number, such as 40w, to lessen
the risk of inadvertently recalibrating TX gain by hitting the TUNE button.
Thanks again, Joe.
73,
Rich VE3KI / VE3IAY
K3 #1595
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