I know Rene HB9NBG does a lot of activations only with his KX2 and AX1 antenna. I also have an AX1/KX2 combo but have yet to try to do it as my only method of activating. Typically it sits in my bag as a backup.
Curious if anyone else here uses the AX1/MFJ telescopic type Whips as a sole method for getting on the air?
I also use a similar antenna (MFJ 1840/1820) with bnc connector and a coil at the base. But only for speedy activations or hard summits where the wheight is important. The pros are its lightness and its “ready to use” feature (but some radials are ever needed). The contra are the need of a tuner (I dont have a radio with tuner like Elecraft) because the swr may be high, and the monoband system (but the change with other stylus is very rapid). The efficiency seems to be very good in 20m (in 40 i’m not satisfied).
73 de Claudio
Needless to say, I’m a fan of those whips (and now the AX2).
ETA: My QRZ bio pic is of me using the MFJ-1820t on a tripod because there weren’t any good trees for wires (all were below the summit or short). That was my Reddish Knob activation in 2020: Reddish Knob (W4V/HB-002) - SOTLAS
ETA2: Except for the Reddish Knob activation where I was using a Yaesu FT-817nd, I typically mount the whip directly to the radio (KX2), the counterpoise to a factory thumbscrew on the case, and use the internal mic. This way, I can use it like a big HF handi-talkie.
I use an AX1 with a KX3 and have used it for activations. I have also set it up at home in the back yard to chase and make regular QSOs as well. I only operate portable and sometimes even at home it is nice to setup quickly due to time. I have had good luck on 40m, 30m and 20m with the AX1 and the 40/30m coil and longer counterpoise. I usually attach both counterpoise and then screw in/unscrew the 40m coil as needed. The antenna is always attached directly to the transceiver and I have made CW and SSB contacts using it.
You could have just strapped the wire to the bushes. The summit is not barren. When I activated the Ruchen HB/BL-004 I just hung the wire horizontally into the branches, about 2-3m (6-10ft) above ground. Seems to me that this gave me a “not so bad” activation, covering the usual suspects in Europe and even a transatlantic QSO.
I used the AX1 and the AXE1 recently on I/AA-091, I/AA-187 and I/AA-162 in the Alpes working SSB.
In my opinion it is weaker than a wire antenna, reports are usually weaker, number of QSOs less. However the AX1 is a very good choice in case of limited space or on crowded summit or for a quick activation. I use it with the AXB1 bipod option and always try to place the KX2/AX1 as high as possible, e.g. on a stone, trying to sit below/deeper to not block radiation.
Even if I do not use it to often I do not want to miss it. It is a very good backup antenna which is always part of my SOTA package.
It’s barren enough. What you’re not seeing behind the photographer is a parking lot full of people and cars. The only trees or bushes that could be used as supports were in the pic, the tallest of which is only 3-4’ taller than the ground I was sitting on (perspective of pic makes it look taller). The rest of the summit drops away steeply from he parking lot. If not for having the whip, I might have tried tossing a wire over a short bush, but the whip seemed like a better choice…and maybe it was since I got my contacts and even worked some DX.
Not my picture but it was the only one I could find that showed the entire summit. I was at the end opposite the entrance.
It is known that these shortened antennas require a counterpoise in the form of a quarter wavelength horizontal wire. Usually placed on the ground, better still in bushes about 1-2m high.
I assume that the counterpoise is essentially or even mainly involved in the radiation. The low height above the ground has less of an effect on a summit.
It might be enough to put a classic dipole or EFHW on the floor if you need something fast or if you want the activation to be unobtrusive.
The detuning of the antenna must certainly be compensated by a tuner.
At the end of my next activation I will experiment with an EFHW on the ground.
These short whip aerials can give surprising results although probably not as effective as a full sized aerial.
I have a Diamond RHM8B which normally mount on a camera tripod with three quater wave ground radials. On 40M have had quite good success, a VK3 operating from his car with a Diamond mobile whip could not believe I was using a whip sitting on a camera tripod.
Some DX on 20M when band conditions permit.
Tried the Elecraft AXB1 mount but found it rather flimsy and a weak mount.
These sorts of whips are very handy on summits where it is difficult to set up a aerial.
I also have a Diamond RHM8B and it saved me many times when the summit were rocky or not enough room.
And my first S2S with NA (KR7RK) was with the RHM8B mounted on a tripod and running 5 watts.
Great wee compromise backup antenna for 17, 20, 30 and 40m. Always carry it as it takes up almost no room in my bag. Tiny and light but much better for CW than SSB. Easy to deploy on a tight summit but homebrew wire antennas are hard to beat if space allows. 73 Mike
To be honest, I could barely read you and understood maybe 30% of your words, but it was a valid contact!
During the other S2S from EA3, you were much, much easier to copy. But we both were on different summits, with different antenna setups and most important, there were different radio conditions.
What would be interesting to make a comparison by using the two setups with two WSPR transmitters at the same time. Of course, there would still be some error involved, but much less, especially if running the test for some time.
In this context, an interesting antenna test using WSPR, that was executed before my SOTA time, can be found here (in German).
An easier but less accurate test could also be made by switching between both antenna configurations and asking the other station the report, while switching back and forth.
The original thread topic was about screwdriver antennas, that may be a compromise solution for a quick setup or where space is restricted. To reduce the ground losses of a such shortened quarter wave antenna, it’s important to either have at least one elevated (resonant) radial or another good ground system.
An interesting solution could be the Kommunica Power HF-PRO-2-PLUS-T that Ed @DD5LP used successfully. It’s light, a bit longer (I think in total 2.7m) and works without a tuner. There are several similar other systems on the marked, also Chinese clones. I probably would go for a minimalistic solution by simply mounting the antenna to a ground spike, but with several shorter radials laying on the ground. I’m aware that a ground spike could be a challenge on rocky/sandy soils, which would need some improvisation skills .
Hello Stephan, I will certainly try your suggestions. When my friend Uwe, DK8OA is back from vacation in 2 weeks, we will compare two identical 20m long EFHW - one inv v and one on the ground directly, also via RBN.
I have no plans to put my antenna on the ground in the future, but I’m interested in whether the shortened verticals actually radiate power, or essentially the conterpoise.
There is very detailed mathematically based literature on this
Gerd Janzen. Kurze Antennen. Entwurf und Berechnung verkürzter Sende- und Empfangsantennen. Franckh’sche Verlagshandlung Stuttgart
The theory always assumes an ideal counterpoise and the efficiency is largely determined by the quality of the extension coil and even more by the earth resistance.
With a freely hanging 1/4 lambda radial, it should be sufficiently small, but then this part also radiates. IMHO the short vertical portion only serves to tune the shortened dipole. Then why not let 1/2 lambda radiate.
I am interested in whether this is actually the case.
That probably depends, e.g. if the radial(s) is (are) elevated and in resonance or if the counterpoises are laying on the ground. Until now I just experimented with elevated and resonant radials, both center fed, or OCF to get the impedance closer to 50 Ohms. There is still a lot I have to try and learn!
Yes, I heard about this book previously, but didn’t find it in a shop, preferably in epub format. Do you know of any source?
Yes, I used several times such antenna successfully, mainly for DX on 12 and 10m with my 6m tall mast. Very quick to setup, especially when no guying is needed.
If I recall right, the lowest angle (over average conductive ground) you get with a vertical antenna of about lambda 0.75 tall, but a quarter wave matches well to the coax (and with ground losses sometimes even better ) and I like simple solutions that don’t need a tuner.
Since we both already have a high-Z broadband transformer, the length of your non-conductive pole (or tree) is the limit for a lambda 0.5 vertical antenna that performs pretty well for DX.