[Elecraft] AX1 Disappointing Performance
Mike Fatchett W0MU
w0mu at w0mu.com
Wed Sep 25 22:19:18 EDT 2024
You have a small compromised sized antenna and QRP. Maybe your
expectations are a bit off. Many people seem to do quite well with
mobile setups using hustler/hamsticks. If you are going camping how
about a dipole or similar? Toss a dipole in a tree for 20m is easy.
You are wasting your time on 40m in Idaho and probably 30m.
W0MU
On 9/25/2024 4:57 PM, Dave (NK7Z) wrote:
> 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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