[Elecraft] K2 / KPA ALC problem. Disconnect VRFDET?

[Don Wilhelm]

Chris,

That is *not* in the newer manual that I have, and it is *not* 
reasonable to do disconnect VRFDET.
Secondly, removing the VRFDET signal from the K2 MCU will cause the K2 
(and KPA100) to go to full output at all times - sometimes in excess of 
160 watts.  If that continues, the base K2 PA transistors will be 
stressed and will fail in a short time.

Bottom line - don't disconnect VRFDET.

It may be that your KPA100 wattmeter is not properly calibrated. Put an 
external wattmeter in the coax link between the KPA100 and the KAT100 
and see if the wattmeter closely follows the power requested setting on 
the K2.  If it goes to full power, then the wattmeter diodes may be 
damaged.  OTOH if the power is quite different (more than 15%) than the 
requested power, you will need to calibrate the KPA100 wattmeter.

73,
Don W3FPR

On 12/13/2013 12:55 PM, Chris Kimball wrote:
> The KAT-100 manual, page 33, suggests disconnecting the VRFDET line at the
> K2 in the event of "Erratic power control with K2/100".
>
> Since may KPA/KAT are in the same box, it's unlikely I'll use the KAT
> without the KPA.
>
> Does this seem reasonable?
>
>