Re: K3 Power Output

Posted by Julian, G4ILO on
URL: http://elecraft.85.s1.nabble.com/K3-Power-Output-tp3563445p3565662.html

hb9ari wrote

Hi Trev,

Since the beginning, i always get the same behavior
with my K3 #1212 (factory build). I work
essentially with JT65A mode; as this mode
is a single tone mode, i've set the modulation
level just before full ALC and power to 50W
(for DX only...). At the beginning of a
JT65A transmit sequence, the power start
at ~ 25W and go up to ~ 48W in 3 to 5 sec.
If  the PA temperature is at ~ 40 to 46°C,
the power variation is lower and power
output start at ~40W; i'm certainly
wrong, but i've always thought that this
was related to PA temp and, as i never get
an output power higher then selected,
this was not a problem in my case.

What is a problem for me is the transmit
audio response; i've tried to adjust XTAL filter
without success; TX EQU compensation
too. As my VFO working frequency
is always set to the JT65A "preferred"
frequency, it's the audio frequency who
defines the actual output spectrum;
for some audio values, i get well over 3dB
output power variations between some
JT65A instantaneous frequencies;  for example,
with a 45W max power, for somes frequencies,
level go under 20W;  i work  with this since more
then one year and i'm always hoping that
the AGC of my correspondent can handle
a "little" ~3dB RF input variation (the QSB
is generally higher...)

Sorry for this time and bandwidth consuming
message.

73 QRO de Rudolf, hb9ari

Are you not using DATA A for this, Rudolph? If so, you can set the audio drive for a steady 4 bars in the "ALC" scale and the K3 will adjust the power for the value selected across the whole range of the audio spectrum (that you might reasonably want to use.)

It didn't always work like this, but it has for many months now. Using PSK31 I can click on a signal anywhere from about 300Hz to 2700Hz, call them and get exactly the power requested (within reason, of course.)