re: Peculiar problem on 80 M
Posted by
Torsten Clay on
Sep 25, 2006; 5:12pm
URL: http://elecraft.85.s1.nabble.com/More-information-Need-help-with-fluctuating-power-output-on-K2-tp386379p386395.html
>Fellow Elecrafters:
>
>I have a strange problem with my K2/100 on 80 meters.
>
>The situation is as follows:
>
>I work QRP DX at the low end of 80 M, (say 3508 kHz or thereabouts) with a requested >power of 4.5 watts, and get an indicated 5 watts out.
>
>I then check into the Pine Tree Net on 3596 kHz and crank up the requested power to >10 watts (this is before the relay clicks; I'm still in QRP mode), and I get about 10 watts >out. So far so good, right?
>
>Then I go back to 3508 kHz, without resetting the power request level knob, but the rig >puts out 5 watts, even though the display acknowledges my ten watt request. If I go >back to 3596 the output goes back to 10 watts in agreement with the requested level.
I have seen similar power output glitches with my K2/100. See the link below. In one case, I was getting 160W output on 1.8MHz. This is really bad when you are driving an amp! Having the KPA100 doesn't matter though, the same effect occurs in the basic K2.
I believe these issues are because the K2's TX agc doesn't have any "memory" about what drive level is needed on different bands, but always tries to correct in real time. The agc level for a given power output varies quite a bit on different bands. Changing frequencies rapidly appears to confuse the agc in some cases. In my case increasing the resistor in the agc (R98 if I remember) helped.
see:
http://www.ac6rm.net/mailarchive/html/elecraft-list/2006-07/msg00684.htmlTor
N4OGW
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