KX3 SWR

[Bill Wilkins]

I am getting an SWR indication in the display of 1.8-1 on 10 meters. That is with just a dummy load at the antenna port. I get the SWR on 12,15,17 meters, but it gradually drops down from the 1.8 on ten meters.
20 meters thru 160 it is 1.1-1. ATU bypassed.
With a verified 50 ohm dummy it should be 1.1-1 all over the place.
I have emailed Elecraft to see what they say.
Anybody else ever see this problem ?
73, Bill, WD8JWJ

[Phil Wheeler-2]

How certain are you of your dummy load, Bill? I've
had some which became somewhat inductive above 15
meters, for example -- and that might be a cause
of what you are seeing.

73, Phil W7OX

On 2/9/15 8:51 PM, Bill Wilkins wrote:
> I am getting an SWR indication in the display of 1.8-1 on 10 meters. That is
> with just a dummy load at the antenna port. I get the SWR on 12,15,17
> meters, but it gradually drops down from the 1.8 on ten meters.
> 20 meters thru 160 it is 1.1-1. ATU bypassed.
> With a verified 50 ohm dummy it should be 1.1-1 all over the place.
> I have emailed Elecraft to see what they say.
> Anybody else ever see this problem ?
> 73, Bill, WD8JWJ

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[Bill Wilkins]

Pretty sure of the dummy. Verified with the Analyzer flat as can be. Antenna actually reads only 1.3-1 at the tested 10m freq with the Analyzer. KX3 says 1.8-1 no matter what. I am normally hooked into an HR50 and the KX3 ATU is bypassed for this and should be. KX3 will tune down the 1.3-1 antenna direct as it should to 1.1-1. (no amp)
I don't think the KX3 is actually seeing an 1.8-1, but is confused in itself. 160 thru 20 meters are all 1.1-1.
I am going to do a re-update with the firmware and see what happens.
Did finally get this Reflector thing figured out Phil. Now works pretty good. Happy here.
73, Bill, WD8JWJ

[Bill Wilkins]

Just did the newest firmware update to the KX3, No change in the SWR problem.
Waiting on a reply from Elecraft.
73, Bill, WD8JWJ

[Don Butler]

FWIW, I really don't have the answer, but I have had similar problems with
slightly increased SWR on the higher bands with other transceivers, and have
never worried about it.   Have you checked the swr of your dummy load using
an external swr/watt meter or antenna analyzer? (using the same coax and at
the same frequency of course).   I'm thinking that you'll probably find that
the discrepancy has nothing to do with the KX3 or its meter.

Don, N5LZ

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Bill
Wilkins
Sent: Tuesday, February 10, 2015 9:27 AM
To: [hidden email]
Subject: Re: [Elecraft] KX3 SWR

Just did the newest firmware update to the KX3, No change in the SWR
problem.
Waiting on a reply from Elecraft.
73, Bill, WD8JWJ



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[Bill Wilkins]

Got an email from Elecraft on how to fix this problem.
You have to go into the menu to ATU MD on each band and tap & hold CLR to erase the memory. Then go into each band and tune into a dummy load to re-establish the memory.
Problem fixed.
The staff at Elecraft never cease to amaze me. Special thanks to Howard.
Too Much Fun
73, Bill, WD8JWJ

[Bill Wilkins]

This did not cure all of the problem. with a dummy load at the bnc ATU TUNE gives a 1.1-1. TUNE gives a 1.3-1. Why are they different ?
Looking at the HR50 amp with an analyzer shows 1.3-1, but when I transmit I get a 2.1-1 on the KX3. Why is this different ? Amp works fine. KX3 works fine. They don't want to work together. Could it be a display fluke ?
All test were done on 10 meters. 160 thru 20 are OK. The rest not. All firmware up to date.
Anybody else have swr issues like this ?
73, Bill, WD8JWJ

[Bill Wilkins]

The answer as to why different swr indications between ATU TUNE and TUNE is:
With ATU TUNE the KX3 is looking thru its own ATU. With TUNE it is looking past the ATU. That's how is was explained to me by another KX3/AMP owner.
73, Bill,WD8JWJ

[Bill Wilkins]

Sometimes the fix is a simple one and overlooked. Coax length.
From a suggestion from Howard at Elecraft I tested different lengths of coax between the KX3 and the HR50 amp. Made a big difference with what the KX3 sees from 160 to 10 meters. Now less than 1.5-1 or less. 30 thru 15 now 1.1-1.
35" it is. Longer NO, Shorter NO. Coax between KX3 and the Hatdrock50 Amp.
73, Bill, WD8JWJ

[Bill Wilkins]

Also found out today after I made up a 35" RG58 cable the SWR went back up to 1.8-1.
35" RG8X 1.5-1.  
KX3 definitely particular in this case. Crazy!
73, Bill, WD8JWJ