[Elecraft] K2 RF Output

[Don Wilhelm]

Jerry,

Replace diodes D16 and D17 in the KPA100 wattmeter, and things should 
settle down.
If you attempted to adjust KPA100 C1 while this condition was present, 
balance the wattmeter again, it will change with good diodes installed.
The diodes are 1N5711 type.

That wattmeter is still used as long as the KPA100 is installed on the 
base K2 - reducing the power to less than 12 watts does not take it out 
of line.

CAL CUR should be set at 3.5 amperes with the KPA100 installed. That 
(and the current display) is the current drawn by only the base K2, and 
not to the KPA100.

73,
Don W3FPR

On 8/8/2021 12:24 PM, jerry wrote:
> All,
>
>   My new QRO K2 behaves a little strangely...
>
> On Tune - it makes 108W on 40M, very nice.
>
> But on 20M it behaves strangely.  It won't make more than 20W or so, 
> complains about high SWR. Even though my Heathkit HM-102 SWR/Wattmeter 
> says the SWR is zilch.
>
> So I moved it to a dummy load.  As I turn the power up, it makes up to 
> about 80W, and then says "Hi CURR".  And it claims that the dummy load 
> ( an 800W "Florida RF" resistor bolted to a large heatsink ) is 1.6 to 
> 1, which is totally bogus.
>
> OK, there's a null trimmer for the SWR bridge.  I got it down to 
> 1-to-1 SWR on 20M.  It degrades on higher bands though - up to 1.5 to 
> 1 on 10M.
>
> Now, 20M gives me a max of 45W - above that it complains "HI CUR".  
> It's doing that on all bands.  With the PA off via menu, I get a 
> maximum of about 8.5W before getting the "HI CUR" message. I tried 
> setting the current up a little bit on the CAL CUR menu, but no real 
> difference.
>
>   With a clamp-on DC ammeter ( which I don't trust THAT much ) I see 
> 340mA on receive,
> and just about 3.6A when the display goes "HI CUR".  This is with the 
> PA turned off.  The
> display shows 7W just before this happens.  Hmm, 13.8V times 3.5A 
> means 48.3W DC input.  Seems a little excessive.