[Elecraft] K2 RF Output

[jerry]

All,

    Can I just remove the KPA100 and test the K2 "bare" for current draw?

                  - Jerry KF6VB


On 2021-08-08 09:49, Don Wilhelm wrote:
> 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.