K3 ATU tunning discrepancy

[4Z5TO]

Hi,

The other day I was tuning up on 20M (14.220Mhz thereabouts) and noticed my SWR on the K3 was at 5.3. When I put up the antenna, it was tuned to a less than 2.0 SWR. Accounting for wear and tear over time I thought it might have "slipped" a little, so  I re-tuned the antenna back to 2.0 SWR. Back at the tx it still shows 5.3 and checking on the the MFJ-259B it's still at 1.9-2.1. What could cause the big difference?

BTW the antenna is a HF6V vertical. Most of the other bands show little difference over all.

The K3 was matching 1 to 1.  Any ideas. I'm going to take down the antenna and do a full cleaning as it's been up for a few years.

[4Z5TO]

Grrrrrr...

I completely disassembled the antenna, cleaned and re-aligned/re-tuned it on all bands. I'm getting 1.5 on 20M now and 1.2 to 2.8 on the rest. The K3 ATU will match down to 5.2 on 20M now (same freq.). Unless I figure out why this is, I'll have to set it to BYPASS and go back to my manual tuner and SWR analyzer, not a huge deal but it would be nice to know why the K3 ATU won't give me at least the same SWR I'm getting on my analyzer.

How do I trust what the ATU it is telling me?

[4Z5TO]

Ok everybody.

I am an official nominee for "Lid of the Year" award on this one. Let this post stand as a lesson to others...

With this K3 ATU (as good as it is) you cannot get a 1:1 match to air. Apparently the best I'll on ever get on 14.xxxMhz is 5.2 and that might be with the high humidity. Tesla would have been proud.

I apparently had set the radio to ANT 2 instead of ANT 1.

I did not discover this until I decided to re-read the section on the ATU operation and go step-by-step and see if I missed something. I also received a few emails detailing similar goofs, so I am not alone on this one.

73,
Douglas
4Z5TO

[Vic K2VCO]

4Z5TO wrote:
> Grrrrrr...
>
> I completely disassembled the antenna, cleaned and re-aligned/re-tuned it on
> all bands. I'm getting 1.5 on 20M now and 1.2 to 2.8 on the rest. The K3 ATU
> will match down to 5.2 on 20M now. Unless I figure out why this is, I'll
> have to go back to my manual tuner and SWR analyzer, not a huge deal but it
> would be nice to know why the K3 ATU won't give me at least the same SWR I'm
> getting on my analyzer.

Are you sure that you don't have the wrong antenna selected on 20m in your K2?

--
73,
Vic, K2VCO (ex-4X6GP)
Fresno CA
http://www.qsl.net/k2vco
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[4Z5TO]

Yes, that is what basically happened, These are the types of things that happen when you've been playing with tube based gear your whole life then you find yourself with one of these Duck Dodgers in the 24½th Century devices.

<quote author="Vic K2VCO">
4Z5TO wrote:
> Grrrrrr...
>
> I completely disassembled the antenna, cleaned and re-aligned/re-tuned it on
> all bands. I'm getting 1.5 on 20M now and 1.2 to 2.8 on the rest. The K3 ATU
> will match down to 5.2 on 20M now. Unless I figure out why this is, I'll
> have to go back to my manual tuner and SWR analyzer, not a huge deal but it
> would be nice to know why the K3 ATU won't give me at least the same SWR I'm
> getting on my analyzer.

Are you sure that you don't have the wrong antenna selected on 20m in your K3?

--
73,
Vic, K2VCO (ex-4X6GP)
Fresno CA
http://www.qsl.net/k2vco

[AC7AC]

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