WA5ZNU
Thursday, November 11, 2004 Zulu
 
K2 Power

k2out
At first I thought my K2 had low power out on 12M and 10M. I checked T2 and it is raised off the board. I re-peaked the 10M and 12M band-pass filters on TX and can't get more than about 1W out on 12M and 10M.

Eric Swartz suggested a current draw check and said that high draw would point to LPF problems and low draw to T2 or BPF.

Unfortunately, I've discovered the problem is worse than I thought. I have good output below 20M and it drops precipitously at 20M and above, as does the current. (4MHz has a dip, but that could be due to the LPF, since the current is steady there, so I'm willing to believe that's a different problem.)

I've also plotted the efficiency assuming 12.5V, but neglected to measure it. If the voltage is constant and I only want a relative measure, it doesn't matter, though. (Also my K2 internal DVM seems to be off a few tenths of a volt.)

I guess my next step is signal tracing.

Note efficiency is at an assumed voltage level of 12.5v and should be used only for a rough relative estimate.

MHzWattsAmpsEfficiency
3.515.32.2554
411.42.536
7.1516.42.4852
10.12514.72.3250
1410.72.0841
14.355.81.6827
18.166.21.533
214.51.3526
21.453.21.1821
24.921.71.0812
281.51.259
28.61.11.127

- posted by Leigh @ 18:31 z
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