[Elecraft] Re: KAT100 alignment: a DOH! moment

[Wayne Burdick]

Hi Peter,

Yes, this is what you need to do. Advancing the pot 20% improves SWR measurement
accuracy. It compensates for an inherent underestimation of reflected power by
any Bruene-style bridge with a resistor at the center tap of the transformer.

73,
Wayne


Peter Halpin wrote:
> 
> Hi all,
> 
> Now that I have recovered my KAT100 from the Christmas tree I am faced by a
> small problem.
> 
> I don't quite understand the KAt100 manual errata sheet (dated 7 Nov 2002
> rev A-2) where it says:
> 
> "With power still disconnected from the KAT100, measure the resistance from
> pin 5 of U5 to ground. Multiply this value by 1.2 (120%). Adjust the REFL
> pot, R4, until the resistance measured at pin 5 equals this value."
> 
> Now it's down to me not understanding this properly - but does this mean
> that I align it as per the instructions then disconnect everything and just
> measure the pre-aligned resistance and bump it up 20%? That's the way I
> understand it, but I don't understand just WHY...
> 
> Please help!