[Elecraft] Elecraft AX-1 Whip Antenna

[David Gilbert]

I haven't done much portable operation except for Field Day, and when I 
do I have access to tall trees for some pretty good wire antennas ... 
including wire yagis.

But I did make a portable vertical antenna that I can set up anywhere.  
It uses four 4' long 1/2 inch diameter aluminum tubes that fit together 
end to end, sitting on top of another 4' long 1/2 inch diameter graphite 
rod as a base.  Four radial wires act as guys for the top of the 
graphite rod, and four thin nylon lines act as guys about 2/3 of the way 
up the vertical.  The radials and the nylon guys lead to the same four 
stakes (or rocks, as the case may be).  I've timed myself and I can put 
it up by myself in about ten minutes, and everything fits in a backpack 
except for the five 4' lengths that I can easily carry as a bundle with 
one hand as I walk.  It feeds very easily with the tuner in my KX2.  It 
was of course designed for 20m, but I've also been able to get a good 
match with the tuner on 40m and 15m.

I couldn't care less about pedestrian mobile, and it's no more hassle 
for me to carry that antenna to set up somewhere than it would be to 
carry a hiking stick.  The heaviest antenna item in the backpack are the 
stakes.

I once set the antenna up on my deck and monitored PSK Reporter for FT8 
signals on 20m over the course of 24 hours.  I got hundreds of hits 
across the entire U.S., of course, but also dozens in Europe, dozens in 
southeast Asia, a couple in Africa, and 8 or so in central Asia.  I can 
send you the screenshot if you'd like.

Maybe some day I'll make a YouTube video of setting it up and making 
contacts to see how far I can get with it.

Dave  AB7E



On 9/23/2022 11:10 PM, Dan Presley wrote:
> I wanted to revisit this discussion to add a perspective that I think needs to be considered. First,as far as modeling short verticals I believe it’s possible to use something like the ‘poor man’s’ AX1 that Doug Hendricks developed at Pacificon in 2019.  A group of us from Oregon went and participated in the build,and subsequently Doug posted the plans and parts list in the QRP quarterly. So if you don’t want to obtain or borrow an AX1 for testing here’s an inexpensive alternative. Build it and give us your results.
>
> Second-I want to hear from Dave AB7E in particular what antenna(s) you use when you’re operating in the field,and specifically when you can’t set up a wire; maybe no trees or a bare summit, or as Thomas K4SWL talks about-when you really don’t or can’t throw up a wire (check out his blog on recent operations in Canada). Or pedestrian mobile. So far I’ve seen nothing that is as compact,lightweight  and easily packable as the AX1 or 2, and that’s important to me when  I’m hiking. Each part is no more than 6” in length or less. Oh-and by the way I just completed another’S2S’ (summit to summit) contact on 30M using the 40/30 add on coil with the AX1 with KR7RK from Oregon to AZ both at 5W.
> Personally I always prefer a wire antenna if possible-either an end fed or as is spelled out in the manuals for the KX3 and KX2, a length of wire about 25-28 feet with a counterpoise. But sometimes it’s not an option. Share with us..I’m always wanting to hear what others do or build. How do you solve this?? Thanks.
>
> Dan Presley 503-701-3871
> danpresley at me. com
> N7CQR at arrl.net
>
>
>> On Sep 22, 2022, at 10:09, Wayne Burdick <n6kr at elecraft.com> wrote:
>> 
>>> On Sep 22, 2022, at 9:47 AM, Jim Clymer <ws6x.ars at gmail.com> wrote:
>>>
>>>
>>>
>>> On Thu, Sep 22, 2022, 11:28 AM Wayne Burdick <n6kr at elecraft.com> wrote:
>>> Yes indeed.
>>>
>>> This is why you need an ATU when using such antennas. The ATU can correct for terrain, counterpoise length and deployment, body capacitance, conductors associated with other connected devices, etc.
>>>
>>> Wayne
>>>
>>> So that would lead me to believe that matching requirements for bicycle mobile with a trailing counterpoise would be a moving target.
>> I haven't tried that myself but yeah, probably.
>>
>> However, radios like the KX2 and KX3 are tolerant of dynamic SWR variations. For example if you hit the ATU button at some point and the SWR goes to 1:1, then walk (or bike) over varied terrain that causes the SWR To vary from 1:1 to 2:1, the radio won't complain. Only if the SWR gets really high will power rollback occur.
>>
>> Without the ATU, and using an electrically short/narrowband antenna, you might see SWR vary from 1:1 to 10:1.
>>
>> Wayne
>> N6KR
>>
>>
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