[Elecraft] Power too high in PSK31 / S

[Don Wilhelm]

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
>
>   
>