[Elecraft] AX1 Disappointing Performance

[Dave (NK7Z)]

Hi,

If possible raise the antenna higher.  Add more radials...

A friend of mine has one of these and we took it out at a portable 
station using a KX radio.  It was 6 feet above the ground, and had 6 
radials on it, each around 20 or 30 feet long, sloped heading to the 
ground.  We used WSPR on it during the big eclipse a few years back, and 
it worked really well, hits all over the world on 20...  Radials are the 
key to making it work better. Being a shortened antenna it will never 
work as well as say a 6BTV, but it will work well with a decent set of 
radials.

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

My favorite definition of an intellectual: 'Someone who has been educated beyond his/her intelligence'.  Arthur C Clarke

On 9/25/24 15:17, James Bennett via Elecraft wrote:
> Several months ago I started building up a POTA station, including a KX3 (with internal tuner), the AX1 Dual Band Antenna, the AXE1 40 Meter Extender, and the AXT1 Tripod Adapter. This afternoon I finally got the time to see how this antenna plays. I was a bit disappointed. Here is the setup:
>
> KX3 (with internal tuner), 25 feet of RG-316 with ferrites on the radio end, five foot tall carbon fiber tripod sitting in the middle of my back yard; no other resonant antennas on the property.
>
> The KX3 / ATU WAS able to find a match to the antenna on all the bands. At first I thought that was great. But being a bit curious, I disconnected the coax and hooked up my Rig Expert AA-55 Zoom. Ughhh. On 40 meters, with the long radial attached and suspended 4-5 feet above the yard, the antennas was resonant at 7.574 MHz - that’s a tad more then the +- 200 KHz stated in the specs. And quite ugly for where I wanted to operate: 7.052 KHz. So, I added the shorter radial, also up above the ground, going a different direction. NO CHANGE to the resonant frequency. Yes, I did have the AXE1 installed, and yes I had the switch set to the “20m” position.
>
> OK, let’s give 30 meters a try. I set the switch to “17m”, and the Rig Expert to 10.116 +- 5 MHz. Yikes - the thing was resonant at 8.070 MHz - very long way from 10.116. Adding the short radial changed the SWR at that frequency from 1.46:1 down to 1.33:1 but no change to resonant frequency.
>
> 20 meters didn’t fare much better. I set the switch to “20m”, removed the AXE1, and connected only the short radial. Minimum SWR of 1.34:1 was seen at 15.330 MHz. At my desired operating frequency of 14.052, the SWR was 6.9:1. Not a very good SWR but one that the ATU can easily handle.
>
> 17 meters was just as bad. With the short radial it was resonant at 19.780 with an SWR of 1.15:1; at 18.116 it showed 6.83:1 SWR. Again, something the ATU can deal with, but…..
>
> While I understand that this is a compromise antenna and it isn’t going to be spot on on every band, I’m a bit frustrated in what I’m seeing here. With five watts output into those kind of SWRs, I’m sure I’m loosing quite a bit of my power in heating the coax and the modules in the ATU. I hesitate to go out on a maiden POTA activation with an antenna showing close to 7:1 SWR at my operating frequencies, even though the ATU “corrects” that.
>
> Any suggestions here? Is this “normal” for the AX1 and AXE1?
>
> Jim Bennett / K7TXA
> Eagle, ID
>
> SKCC #10447T
> B.U.G. #301
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