KAT500 autotune

[Poul Erik Karlshøj (PKA)-2]

KAT 01.58 is working nicely. But still, if Your antennas are changing impedance as the WX changes (which I can confirm is the case when antennas are mounted in or very close to trees :-) You are going to hear these sometimes lengthy clickety-clack. Even when making two configurations (one for dry and one for wet WX) You have all "shades" in between, so once in a while You are going to have the relays going crazy again. At least it happens to me.
This made me think if it might be avoided keeping in mind that the K3 ATU does the tuning a lot less noisy.

I think others have suggested a firmware change making autotune of KAT500 initiate from the K3. This may be an interesting way to get rid of the clickety-clack of the KAT500 if done as follows when selecting TUNE on the K3 (new mode: KAT500):
- KAT500 enter bypass (KPA enters STBY) and K3 performs the autotune
- K3 ATU config transfers to KAT500
- K3 ATU changes to BYPASS
- KAT500 changes to MANUAL
if the cables from K3 to KPA are not so good it may be that the KAT needs to fine tune. So a fine tune of the KAT might be a good idea.

73/OZ4UN
Poul-Erik

Sendt fra min iPad
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[Stephen G4SJP]

An ingenious idea but I think there is a flaw in the argument, in that at
the position of the K3's ATU there will be a different impedance to match
than is the case at the KAT500's position further along the line.  Not only
will the impedance move around the Smith Chart a bit but there is also the
input impedance of the KPA500 to consider.  Maybe in practice all of the
above may have a negligible effect, but I somehow doubt it.

73 Stephen G4SJP


On 23 February 2014 12:58, Poul Erik Karlshøj (PKA) <[hidden email]> wrote:

> KAT 01.58 is working nicely. But still, if Your antennas are changing
> impedance as the WX changes (which I can confirm is the case when antennas
> are mounted in or very close to trees :-) You are going to hear these
> sometimes lengthy clickety-clack. Even when making two configurations (one
> for dry and one for wet WX) You have all "shades" in between, so once in a
> while You are going to have the relays going crazy again. At least it
> happens to me.
> This made me think if it might be avoided keeping in mind that the K3 ATU
> does the tuning a lot less noisy.
>
> I think others have suggested a firmware change making autotune of KAT500
> initiate from the K3. This may be an interesting way to get rid of the
> clickety-clack of the KAT500 if done as follows when selecting TUNE on the
> K3 (new mode: KAT500):
> - KAT500 enter bypass (KPA enters STBY) and K3 performs the autotune
> - K3 ATU config transfers to KAT500
> - K3 ATU changes to BYPASS
> - KAT500 changes to MANUAL
> if the cables from K3 to KPA are not so good it may be that the KAT needs
> to fine tune. So a fine tune of the KAT might be a good idea.
>
> 73/OZ4UN
> Poul-Erik
>
> Sendt fra min iPad
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
>

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[Poul Erik Karlshøj (PKA)-2]

Yes Stephen thats true. The cable length is the cable from K3 to KPA plus KPA input to output (50 ohm straight through if in STBY) plus the cable KPA to KAT plus the KAT input to output in BYPASS (50 ohm straight through?). In my case it might be a total of 1.5 meter which is much on 6m but not very much on 160m. Still it might be a lot less relay chattering in the KAT500 even if it needs to include a fine tuning.

I had another idea, which unfortunately requires a big hardware change: install smaller and quieter relays, one in parallel with each of the bigger relays. Do the (low power) tuning using the small relays and then copy the relay config to the bigger relays and open the smaller ones. Maybe for the "next generation" KAT.

Sendt fra min iPad

> Den 23/02/2014 kl. 14.44 skrev "Stephen Prior" <[hidden email]>:
>
> An ingenious idea but I think there is a flaw in the argument, in that at
> the position of the K3's ATU there will be a different impedance to match
> than is the case at the KAT500's position further along the line.  Not only
> will the impedance move around the Smith Chart a bit but there is also the
> input impedance of the KPA500 to consider.  Maybe in practice all of the
> above may have a negligible effect, but I somehow doubt it.
>
> 73 Stephen G4SJP
>
>
>> On 23 February 2014 12:58, Poul Erik Karlshøj (PKA) <[hidden email]> wrote:
>>
>> KAT 01.58 is working nicely. But still, if Your antennas are changing
>> impedance as the WX changes (which I can confirm is the case when antennas
>> are mounted in or very close to trees :-) You are going to hear these
>> sometimes lengthy clickety-clack. Even when making two configurations (one
>> for dry and one for wet WX) You have all "shades" in between, so once in a
>> while You are going to have the relays going crazy again. At least it
>> happens to me.
>> This made me think if it might be avoided keeping in mind that the K3 ATU
>> does the tuning a lot less noisy.
>>
>> I think others have suggested a firmware change making autotune of KAT500
>> initiate from the K3. This may be an interesting way to get rid of the
>> clickety-clack of the KAT500 if done as follows when selecting TUNE on the
>> K3 (new mode: KAT500):
>> - KAT500 enter bypass (KPA enters STBY) and K3 performs the autotune
>> - K3 ATU config transfers to KAT500
>> - K3 ATU changes to BYPASS
>> - KAT500 changes to MANUAL
>> if the cables from K3 to KPA are not so good it may be that the KAT needs
>> to fine tune. So a fine tune of the KAT might be a good idea.
>>
>> 73/OZ4UN
>> Poul-Erik
>>
>> Sendt fra min iPad
>> ______________________________________________________________
>> 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

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