Posted by
Don Wilhelm-3 on
Mar 09, 2006; 8:10pm
URL: http://elecraft.85.s1.nabble.com/K2-low-power-on-160m-tp387410p387411.html
Glenn,
The most likely reason you did not get a response is that none of us have a
good immediate answer.
I suggest that you look at the RF voltages at the collector and base of Q5,
Q6 and Q7/Q8 to determine where the problem is located. You can use a
'scope or an RF Probe to check the RF voltage levels (if using an RF probe,
do not measure the collectors of Q7/Q8, you may zap the diode). Compare the
readings obtained on 80 meters with those obtained on 160 meters. What you
are looking for is a stage that has lower gain on 160 meters, so the
measurements may be a bit more complex than a simple comparison - the K2
power output control may try to push the RF voltages on 160 higher trying to
produce more output - so do the comparisons at a power level that your K2 is
capable of delivering on 160 meters (the 2 or 3 watt level should do fine).
73,
Don W3FPR
> -----Original Message-----
> Dear all
>
> I tried to send this question to the reflector yesterday but I
> haven't got any responses so maybe the message did not make it
> onto the reflector. One more try...
>
> I finished building K2 s/n 5361 Tuesday and managed to align it
> on all bands 80-10m per the specs in the manual.
> First tests (RX only) showed a wonderfully quiet receiver with
> "good ears". TX is well within specs, up to 15W power out.
> Encouraged by the FB results I started constructing the 160m
> extension yesterday. No worries during assembly as far as I could see.
> Then, after having installed the 160m PCB into the K2 I started
> the alignment procedure.With 2W out all was OK both on 160 and
> 80m, no problems peaking output power to about 2,5W. However,
> when I try to crank the output power up to 10W as per the
> instructions on p9 of the installation manual, I am unable to get
> more than 6W output on 160m. 80m is OK (up to 16W output).
> I have tried the alternative frequencies for peaking. 2W out is
> OK all the time, but I get no more than 6W when I should be
> reading 10W out. Cal Cur is set at 3.50A. Checked all solder
> joints, toroid winding numbers, what have you.
>
>
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