[Elecraft] K2 KPA100 SWR Bridge Readings Way Too High

[Don Wilhelm]

Dick,

Is that voltage at U5 pin 3 actually negative?  If so diode D17 is 
backwards - the voltage should be positive in all cases.  Yes, C1 will 
not adjust if the D17 polatity is wrong.
You can refer to the parts placement diagram at the back of the KPA100 
manual if you cannot see the silkscreen clearly.

After putting D17 in correctly, recheck the 43k initial setting of R27 
and go from there.

73,
Don W3FPR

On 10/3/2017 2:08 PM, Dick Lamb wrote:
> Don,
>
> I set both R26 and R27 to 43K Ohms, applied power directly to the base 
> unit (no power to KPA100), and set power know to call for 10 W.  In 
> TUNE mode the SWR reads about 9.9:1 regardless of C1 setting.  I think 
> the C1 setting has no effect.  I measure the power out at about 15 W, 
> and the K2 says it's putting out about 5 W.  Voltage at U5 Pin 3 is 
> about -1.040 V.
>
>