Check out LY2H’s video here:
Built a smalll cap hat to bring SWR into acceptable levels - using radio without tuner with AX-1.
Also, K4SWL, has a few youtube vids as well on using the AX1 for several QRP outings…
I have an AX1 but haven’t used it much. I did build the small cap hat and it does work…
73, Todd KH2TJ
Karl (OE6LKG) has the AX1 and we usually use it whenever we do an activation together. In fact, we will probably be using it tomorrow on the Lukaskogel OE/ST-496. We usually put it up a 4m mast and try to keep the counterpoise as high off the ground as possible, in which case, it works pretty well all of the time. I am not a fan of having either end (or feedpoint) of any antenna close to the ground. I always raise up the feedpoint and carry about 3m of RG174/316 with me to make the connection to the radio.
73 de OE6FEG
MattThis evening I quickly rebuilt an elecraft ax1 antenna. As a prototype in a cardboard box and with a variable toroid coil.
Tomorrow I will do the first tests on a summit and compare them against an inv v efhw and one lying on the ground.
73 Chris
Hello Christoph,
Very interesting experiment !
What are the specifications of the coil ?
73,
Bruno, F6HHK
I measured the inductance at 5.7uH. If I like the concept, I’ll post the specs of the coil (number of turns, diameter, wire size).
73 Chris
it’s a coil on a ferrite or plastic tube ?
I guess it’s a ferrite core in a plastic toroid.
73 Chris
Today I was on the summit DM/NS-122 and tested 3 different antennas for the 20m band.
First, the self-made ‘whip’ antenna similar to the elecraft ax1 against a 10m long efhw, which I deliberately placed on the ‘ground’ - see my last post.
The result showed that ‘whip’ and ‘ground’ have different polar patterns and ‘ground’ works at least as well as the other.
DL1CR Wiph vers Ground efhw antenna - YouTube
Then I compared the whip antenna with my 20m long efhw inv v.
The ‘whip’ performed surprisingly well and was only marginally weaker. In the subsequent qso with the whip I got an S8 from Greece, which surprised me a lot.
DL1CR Whip vers Efhw with qso - YouTube
My summary: All three antennas have their justification. But I’ll stick with my inv v efhw, because I can work well all bands with it. However, if there is little space on the summit, there is a sensible alternative
73 Chris
I confirm the good performance of the whip antenna for 20m. Today I was on I/VA-120 (I contacted you but on 30m) and with this antenna I had qso with SM, UW and SP, all with reports not less than 559 (some with 579 or better (!?!)). My rig was an SW-3B (5W) and the whip (MFJ 1820T) had 4 radials of 5m (see pic)
I’ve used my AX1 a number of times in SSB. The most success I’ve had is with the counterpoise elevated across a bush or tree. I always take it as a backup to my SOTABEAMS bandspringer.
I’ve never used the AX1,… … and I’ve never missed it, let alone needed it.
It was always too expensive for me to try or play with. A self-build, as Chris @DL1CR has done, I had never considered.
But for me, the rule is: - get as much antenna wire as high in the air as possible.
I haven’t compared the weights and packing dimensions in detail now, but if you just take wire (maybe with a toroid) and use your hiking poles as a mast set, you’re already better off here. In alpine rocky terrain, I have also sometimes successfully put a wire just on the rocks and used them virtually as a mast.
Even if you take a small portable telescopic mast (fishing pole) for the wire, you will not have the very big disadvantage in weight and pack size.
As I read, the transmission frequencies to be used with the AX1,… are also quite limited, so that a tuner is recommended. So there would be no great advantage here either.
So far, I have not been able to identify any significant advantage of the AX1,… over a wire antenna. At the moment I can not imagine a situation where I could not build up ( throw down ) a wire antenna.
73 Armin
About antenna size… this is my endfed for 17, 30 and 60m with current balun, balun 1:49 and traps
Same here Chris, but I’ve shortened my inverted V to 15m, as I find it more convenient.
73 de OE6FEG
Matt
Hi Chris,
in your first test, did you also transmit? My experience (see above) was that in receiving, the audible difference was not so big. But transmission did not result in an QSO when the wire was on the ground.
In your second test, the vertical transmission pattern may have offset the lower transmission efficiency in order to reach Greece.
Maybe a better test would be a WSPR experiment or testing via the Reverse Beacon Network: calling CQ on slightly different frequencies with different antennas and then checking who spots you.
Thanks for the tests!
73 de Martin / HB9GVW
A test via Wspr or RBN would certainly be more meaningful. But in my view it makes no difference whether you compare the reception field strength of the other station when receiving or the reception field strength at the other station when sending.
The example with the FT8 reception makes it clear how complex the topic is. How do I compare two antennas in practical use on the band.
1- The antennas cannot be in the same location at the same time without affecting each other.
2- The antennas usually have different directional characteristics and preferred polarization
There is no such thing as the ideal antenna for the summit. It would be best if there were several designs that you could switch over.
73 Chris
I owned a MFJ 1840T stick from long time ago and nevera I get a qso with It. However the reception is quite enough also un 20m band.
I use the recomended counterpoise from MFJ, 7.1m (not remember, maybe).
If I put the whip in the SWR analizer I can get a good value of swr, squizing up and down the whip…
