[Elecraft] K2 RF Output

[Don Wilhelm]

Jerry,

Are you measuring the power output with an external wattmeter?  Or are 
you depending on the power setting in the base K2.  Use an external 
wattmeter while troubleshooting this problem and a dummy load (not an 
antenna) connected to the wattmeter.

The K2 power will fold back when the CAL CUR point is reached.  I still 
say it is a wattmeter problem because that is the normal problem.

Leave the KPA100 connected, and place it 'on its back' on a box or book 
about 1/2 the height of the K2.  Remove the shield and get out your DMM.

When you have done that, send me an email off-reflector (direct email 
and take {Elecraft}  out of the subject line.
The troubleshooting details are not likely of interest to the rest of 
the list.  You can summarize the results to the list when it is resolved.

73,
Don W3FPR

On 8/12/2021 1:22 PM, jerry wrote:
> On 2021-08-08 09:49, Don Wilhelm wrote:
>> Jerry,
>>
>> Replace diodes D16 and D17 in the KPA100 wattmeter, and things should
>> settle down.
>
> *** The diodes came in from Mouser yesterday, and I replaced them.  
> Things
> are still not right.  I did get a good adjustment on C1, and it now 
> reads 1 to 1
> on all bands.
>
>    HOWEVER, it still will not give full power. It fails with "HiCUR".
>
>   If the KPA100 is installed but not powered up ( power from the 
> barrel connector ),
> it gets to about 8W then fails "HiCUR".
>
>   If the KPA100 is installed AND powered up AND enabled via the menu:
>    on 40M, it gets to a bit over 80W, then says "HiCUR".
>    on 20M it gets to about 65W, then "HiCUR"
>
>   If I uninstall the KP100 completely, the radio gives full power - 
> 15.3W on
> 20M, 16.7W on 40M.
>
>   Very mystifying.  I made up a cord to connect the barrel connector 
> to my lab supply.
> Interesting results:  with the KPA100 connected but power through the 
> barrel, the radio
> simply does draw enough current to shut it down with "HiCUR" at 8W.  
> It shuts down at
> EXACTLY 3.5A measured by the power supply.
>
>   With the KPA100 entirely disconnected, the radio makes 16W on 40M at 
> 3.15A.
>
>   So my conclusion is that something in the KPA100 is drawing excess 
> current, in transmit mode, even though the KPA100 is mostly not 
> operating.
>
>    In "tune" with the power all the way down, and the KPA100 
> connected, the radio draws
> 750mA through the barrel connector.
>
>    In "tune" with the power all the way down, and the KPA100 
> DISCONNECTED, the radio
> draws 440mA through the barrel connector.
>
>                  - Jerry KF6VB
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