Re: [K2][KAT2] Is it working as well as can be expected?

Posted by Don Wilhelm-4 on Aug 21, 2011; 11:06pm
URL: http://elecraft.85.s1.nabble.com/K2-KAT2-Is-it-working-as-well-as-can-be-expected-tp6708777p6709645.html

Chip,

The KAT2 and the KX1 use a similar tuning algorithm, it searches for the
lowest SWR - but the KX1 capacitor and inductor selections are much more
limited than those of the KAT2.  I am surprised that the KX1 gives you a
match, but the KAT2 cannot handle the same antenna.

Try setting the K2 ATU menu to ALT before giving up - that uses a slower
but more critical algorithm.

If the ALT setting still does not produce a good match, yes, you may
have some inductor or capacitor in the L-C section of the KAT2 that is
not doing its job properly.  Even though the relays click when going
through the various menu settings, that only means that the relays are
operating properly.  Whether the relays actually add the inductor or
capacitor is quite another matter.  If the inductor leads are not well
stripped or a capacitor is not well soldered, it will not function as
expected even though its relay is engaged.

There are ways to determine externally whether the inductor or capacitor
are actually placed 'in-circuit' by the relay, but that requires an
antenna analyzer or VNA or similar instrument.
I would suggest that you first do a visual examination of the inductor
and capacitor soldering on the L-C board, and check each relay to assure
that all pins are well soldered.

73,
Don W3FPR

On 8/21/2011 11:38 AM, Chip Stratton wrote:

> I recently bought a K2 (s/n 3873) with KAT2 module (f/w 1.06) on Ebay. The
> K2 is working well, but I'm not sure the KAT2 is. Here is what I get tuning
> into a 25 ft vertical wire with 16 ft counterpoise on the ground:
>
>   f SWR L C Net  3.540 1.2 18.2 0.66 N1  7.050 1.6 3.9 0.24 N1  10.106 1.1
> 1.6 0.05 N2  14.100 2.6 2.6 0.04 N1  18.089 1 1.9 0.15 N1  21.100 9.4 1.3
> 0.09 N1  24.900 1.1 1.2 0.1 N1  28.100 1.2 0.5 0 N1
> My AA-230 analyzed this antenna this way:
>
>   f SWR R X LC Z  3.54 19 465 -478 93pf 668  7.05 15 105 -252 89pf 273
> 10.106 4.2 166 85 1333nh 186  14.1 15 750 78 876nh 760
> I can see that the antenna is pretty close to 1/2 wave for 15m so would be
> hard to tune to. And I can also see that the impedance of 760 ohms is very
> high for 20 meters, so maybe I can't expect an SWR of 2:1 when we're
> starting off at 15:1, but my KX1 gets 1.2:1 using the same inductance but
> .02 nF.
>
> Perhaps the 22 pf capacitor or relay is bad on the KAT2, but would welcome
> any comments. I do hear relay action as I move to each inductor, capacitor,
> n1, and n2.
>
> Thanks,
> Chip
>

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