[Elecraft] Re: Funny KAT100 behavior

[Wayne Burdick]

Vic, this is most likely not a problem. In CAL mode, there is significant stray
reactance which will may make the SWR appear to be high, especially on the
highest bands. The ATU itself can tune out the strays in AUTO mode. 

To quote the KAT100 manual, revision A, page 31:


Bypassing the Matching Network (CAL mode)

You can bypass the matching network by setting the ATU menu entry to CAL. This
sets the L and C values in the matching network to zero. However, there will
still be considerable stray reactance present within the ATU. This stray
reactance may de-tune any antenna or dummy load connected to the ATU's antenna jacks.

As an alternative to CAL, you can tune up the ATU into a 50-ohm dummy load on
each band using AUTO mode. This will cancel out the tuner's stray reactance.
After tuning up on all bands, put the ATU into SWR (x.x-1) mode, which will
preserve the L and C settings.



In the next revision, I'll add a note about this earlier in the manual (during alignment).

73,
Wayne
N6KR



Vic Rosenthal wrote:
> 
> I just finished my KAT100 and I am seeing the following:
> 
> The logic tests were all OK, resistance readings OK, etc.  Nulling the SWR
> bridge gave me a minimum of about 135 mv.  Calibration of forward/refl power was
> done on 7 MHz per instructions without any strangeness.
> 
> The KAT100 is set to CAL and connected to a dummy load.  On all bands EXCEPT 21
> and 28 MHz, the SWR shown on the KAT100 is close to 1:1 and the power reading is
> close to that of my external wattmeter.  On 21 and 28 MHz only (24 is OK) the
> SWR indicates quite high, from 1.7 - 2.0 even though the external wattmeter
> shows close to 1:1.
> 
> Any suggestions on where to look?