[Elecraft] K2 power control ...

[Don Wilhelm]

Bob,

It is normal for the K2 to develop full power if the VRFDET signal is 
not being sent to the K2 microprocessor.  The 20 watts is not the 
problem, but the result.

For some reason, the VRFDET signal is not getting from the KAT100 back 
to the K2.  First check the cable between the KIO2 (or KPA100) and the 
KAT100 to be certain it is connected like the illustration in the KAT100 
manual.

If your wattmeter calibration for the KAT100 was successful, you had 
good level signals at the inputs to U5, and I conclude there is no 
problem with T1 or the diodes in the wattmeter.

Check U5 with RF power applied to the KAT100 - you should have the same 
voltage at U5 pin 1 as the voltage at U5 pin 3.  If that is true, check 
the voltage at U6 pin 3 and the VRFDET signal at U6 pin 6 (should be 
about half the voltage of pin 3).  Be certain you have an active enable 
signal (near +5v) to U6 pin 8.

If you do have a VRFDET signal at KAT100 U6 pin 6, but none at the K2, 
then there is something wrong with the wiring of the VRFDET signal path.

73,
Don W3FPR

F5UL wrote:
> In the lasr email ,I forgot to say that evec with more than 20w output 
> on the
> power meter, the indicated power on the display was only 0.4 w!!!
> 
> Rectification  :  about VREFDET it is 0.8 v , not 1.3v!
> 
> VALC (Q8 emeteur) power set to 0 v=0.8, powet set to max v=2.6 v
> 
> Puting back the KAT2 I have the same reaction power out ~20w with 
> VREFDET 3.8 v whatever
> power asked for.
> 
> With the KAT2 the display is giving the real power as I have on the 
> external wattmeter (more or less 20/22w)
> 
> Regards F5UL/Bob