Elecraft › [K2]

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

Classic

List

Threaded

8 messages Options

Chip Stratton

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

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
AE5KA
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Don Wilhelm-4

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

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
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

k6dgw

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

I would suspect Chip has some sort of problem Don, my KAT2 has never
failed to get a match to anything conductive :-). Actually, it won't
load an end-fed half-wave on 40, but does with a 1.3:1 SWR on 20. Go
figure.

Just out of curiosity, is the KAT2 some sort of steepest descent
algorithm? ... or maybe that's proprietary. At any rate, both my KX1
and KAT2 ATU's really do work.

Fred K6DGW
Auburn CA

On 8/21/2011 4:06 PM, Don Wilhelm wrote:
> 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.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Don Wilhelm-4

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

Fred,

I do not know what the algorithm is (that is a question for Wayne), but
what I do know is that in the KAT2, there are 2 levels - the normal
algorithm which is fast to find a match, and the ALT which is slower,
but will often find a match in difficult times.

73,
Don W3FPR

On 8/21/2011 7:24 PM, Fred Jensen wrote:

> I would suspect Chip has some sort of problem Don, my KAT2 has never
> failed to get a match to anything conductive :-). Actually, it won't
> load an end-fed half-wave on 40, but does with a 1.3:1 SWR on 20. Go
> figure.
>
> Just out of curiosity, is the KAT2 some sort of steepest descent
> algorithm? ... or maybe that's proprietary. At any rate, both my KX1
> and KAT2 ATU's really do work.
>
> Fred K6DGW
> Auburn CA
>
> On 8/21/2011 4:06 PM, Don Wilhelm wrote:
>> 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.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Tony Estep

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

In reply to this post by k6dgw

On Sun, Aug 21, 2011 at 6:24 PM, Fred Jensen <[hidden email]> wrote:

> ...is the KAT2 some sort of steepest descent
> algorithm? ... ...

=============
Fred, I don't know that answer, but the little research I've done into
auto-tuner algorithms suggests that it doesn't have to be too fancy -- some
version of Newton's method, or just a binary search. For a concrete example,
go to:

http://fermi.la.asu.edu/w9cf/tuner/tuner.html

It has a link to the Java code for a simple T-Network autotuner, so you can
follow the code and see exactly the algorithm used.

73,
Tony KT0NY
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Chip Stratton

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

In reply to this post by Don Wilhelm-4

I've tried ALT, that did not improve the match on 20m and 15m. I have also
very critically examined and re-flowed some solder joints without improved
results. I can't identify by inspection any problems with the capacitors and
inductors on the LC board.

I do have a high quality antenna analyzer, a RigExpert AA230Pro, used to
obtain the antenna figures in the second chart in my original post. I've
also attached that analyzer to the antenna port of the KAT2, and activating
each of the inductors and capacitors noted a change in the impedance with
each change, but I did not look at this in a quantitative fashion.

Don, is there a regular procedure for using the antenna analyzer to analyzer
the KAT2?

Thanks,
Chip
AE5KA

On Sun, Aug 21, 2011 at 7:35 PM, Don Wilhelm <[hidden email]> wrote:

> Fred,
>
> I do not know what the algorithm is (that is a question for Wayne), but
> what I do know is that in the KAT2, there are 2 levels - the normal
> algorithm which is fast to find a match, and the ALT which is slower,
> but will often find a match in difficult times.
>
> 73,
> Don W3FPR
>
> On 8/21/2011 7:24 PM, Fred Jensen wrote:
> > I would suspect Chip has some sort of problem Don, my KAT2 has never
> > failed to get a match to anything conductive :-). Actually, it won't
> > load an end-fed half-wave on 40, but does with a 1.3:1 SWR on 20. Go
> > figure.
> >
> > Just out of curiosity, is the KAT2 some sort of steepest descent
> > algorithm? ... or maybe that's proprietary. At any rate, both my KX1
> > and KAT2 ATU's really do work.
> >
> > Fred K6DGW
> > Auburn CA
> >
> > On 8/21/2011 4:06 PM, Don Wilhelm wrote:
> >> 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.
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> >
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Don Wilhelm-4

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

Chip,

There is no regular procedure for using an antenna analyzer with the
KAT2, but if you saw a change in impedance with each of the manual
settings and those changes were consistent with adding (subtracting) the
amount of reactance equal to the particular inductor or capacitor
selected, then you have verified that the tuner is selecting the
inductors and capacitors correctly.

You will have to figure the reactance change from the manual
inductor/capacitor values for the frequency that your antenna analyzer
is using.

73,
Don W3FPR

On 8/21/2011 9:10 PM, Chip Stratton wrote:

> I've tried ALT, that did not improve the match on 20m and 15m. I have also
> very critically examined and re-flowed some solder joints without improved
> results. I can't identify by inspection any problems with the capacitors and
> inductors on the LC board.
>
> I do have a high quality antenna analyzer, a RigExpert AA230Pro, used to
> obtain the antenna figures in the second chart in my original post. I've
> also attached that analyzer to the antenna port of the KAT2, and activating
> each of the inductors and capacitors noted a change in the impedance with
> each change, but I did not look at this in a quantitative fashion.
>
> Don, is there a regular procedure for using the antenna analyzer to analyzer
> the KAT2?
>
> Thanks,
> Chip
>

k6dgw

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

In reply to this post by Don Wilhelm-4

On 8/21/2011 5:35 PM, Don Wilhelm wrote:

> I do not know what the algorithm is (that is a question for Wayne), but
> what I do know is that in the KAT2, there are 2 levels - the normal
> algorithm which is fast to find a match, and the ALT which is slower,
> but will often find a match in difficult times.

Hmmm ... my K2 is currently in its Kopp Kase, but I'll get it out this
afternoon and see what the ATU is set at. I don't recall ever changing
that from the default, but then, I don't remember what we had for dinner
last night either. I *do* know that my KAT2 matches just about anything
long, thin, and conductive, so Chip's should too.

73,

Fred K6DGW
Auburn CA
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html