Except they seem to be out of stock or discontinued and cost about £200 more than making one yourself.
And they’re big, heavy and expensive too.
Back to Matt’s frustration. My experience is you can make nominally centre loaded verticals repeatable and tame if and only if you keep the radials off the ground.
So you are saying you can make this antenna for nothing? Because the Slidewinder DX is £168 and, they are not out of stock, although you can buy the coil separately and source all the other bits yourself,
I have never had any problems carrying mine in my rucsac, in fact, I’ve used it with a G90 on Gun
No, I don’t mean this exact antenna. It just seems a lot of money when you can easily make antennas yourself for a few quid. And it’s more satisfying when you have made it yourself. And 1.3kg does sound quite heavy.
All antennas can be considered some kind of dipole. In this case one side is only 5m long. At 40m you have made an ad hoc OCFD.
On 40/60m your antenna is going to be very small, and thus, even when you get it matched up, low efficiency compared to the EFHW.
I think you are best keeping the EFHW, and just having a separate vertical for 20m up, eg a trapped vertical.
Consider the RV-3C. It is only 3.7m for 20,15,10 or this 3.4m one
My pole is 5.6m actual, so you can slope the radials down as guys from ~2m
Note: The Mosley traps are aluminium tubes with two traps, and the tube is acting as the element between two traps. The traps use capacitance between the outer sleeve and the inner element as the traps C.
thanks for the link to that article, which is apparently written by the proprietor of STEPPIR antennas. It makes a lot of sense. The entire article is not only readable but is consistent with experimental data found by not only me, but many others. I think it contains very good advice on the radial subject.
I must admit I stopped reading the thread after Andrew VK1DA’s posts to which I absolutely agree. Maybe you want to know what vertical I use and which I used for our portable-2-portable QSO on 20th April.
I designed her for the 2015 SOTA 10 m challenge when I wanted some DX’ish antenna for that band. She’s basically a 5/8 lambda radiator over three counterpoises which I usually feed at roughly 2 m above ground level. All counterpoises slope down to 1.4 m which is the maximum length of my walking poles.
So I took a piece of antenna wire (6.2 m) and also made a loading coil for 10 m resonance.
A simple L-match makes the antenna multiband 14, 18, 21, 28 MHz. 24 MHz would be close to halfwave resonance, so it obviously does not work there. Each counterpoise has a link to vary their lengths. A current choke / 1:1 balun is needed at the feedpoint, e.g. ferrite core of mat 43.
I close the coil switch for operation on 14 and 18 MHz, on 21 and 28 the switch stays open.
Don’t ask me which counterpoise length I use on each band, I just can’t remember. If I can’t tune her, I just open/close all links. I was always able to tune, regardless of the summit I was on.
I also tried to make the antenna work on 7 MHz, which needed an additional loading coil (a larger coil with another switch didn’t fit in the small housing) and another switch which connects the capacitor either before or after the loading coil. It seemed to work which means I was able to tune the antenna and I had some QSOs on 40 m. But the linked dipole performed better for inter-euro QSOs and 40 m would not be the band of my choice for SOTA DX. So I abandoned the plan to use her on 7 MHz on a regular basis.
good idea. Will give it a try with 8 radials and will write about the experience a bit later.
The telescopic antenna without the coil and with the 10x5.2m radials is easy to adjust from 14Mhz to 28Mhz by extending or contracting it. If from 18Mhz the adjustment is a bit difficult for you, I recommend you make marks on the radials for each band.
The negative point is that if your rig doesn’t have an SWR meter you have to carry one.
As I mentioned before, for 7 and 10Mhz the rules change a bit. I was never able to adjust it easily with the raidials scattered symmetrically but the only way is to gather 5 on one branch and the other 5 on another branch. This is possibly due to their extension, perhaps I should try with 10 meter radials.
Thanks for the hint!
Intention is to use the coil. But also use the ATU from the KX2.
This worked fine, once the coil is configured for the right band…
Just want to know if increasing the radials from 4 to 8 will make a difference.
There is also the JPC PAC-12 antenna that is worth consideration
I like my antennas like my women… cheap.
Is this correct? I suppose for 21 and 28 MHz a shorter loading coil is required than for 14 and 18 MHz. From your drawing I would conclude that the switch short-circuits the part of the coil under the switch (the upper part). Therefore, I would have expected to be the other way round.
Maybe, I misunderstood the drawing?
on 28 MHz, the antenna is a 5/8 lambda. So you need a loading coil to make it a 6/8 lambda to get 50 Ohms resonance. The capacitor would not be needed there, so it’s set to minimum.
On 14 and 18 MHz it is an extended quarterwave, so theoretically you wouldn’t need any inductance, only the capacitor to compensate the wire length. But there are effects like the counterpoise angle, their lenght which is not exactly 1/4 lambda and probably ground close to the feedpoint. So I practically determined the best (smallest) number of turns which allowed me to tune the system to resonance.
On 21 MHz, don’t ask! I didn’t design the antenna for this band, as it’s not one of my favourites. It accidentally does work there quite nice anyway. Maybe I’m wrong in the number of turns I use on 21, but I definitely remember that I can tune her there and had some DX QSOs.
Hope this answers your question.
My antennas are cheap, so I can spend my money on classy women.
Hi Paul. Without realizing it, I bought parts of the JPC-PAC kit. It was just the peg, the whip support and the coil. Everything is excellently built. From what I saw on the net, the complete kit seems a bit heavy and bulky to carry but not impossible. Instead of the aluminum sections it is preferable to carry a 5m telescopic whip and in this way we will have 1/4 lambda for all bands from 14Mhz. A great advantage is that with the peg and the antenna base, the whole system does not need the support ropes. Many will wonder “And the wind?” In my case I have had strong winds and the whip barely swayed. The three parts that I bought from this kit are really worth it.
Without those 4 alu rods you can only screw the coil to the base. That means you will have less effective base loaded antenna instead (or, with 5.something m long whip, you can have 20 m still without using the coil).
JPC-12 is a good option, my only change was a set of radials - I made 8x5 m and with soil properties around I never had any problem tuning it under 1:1.5.
You’d win the bet! Mostly ground; but everything else nearby that might affect the antenna.
DX-pedition activators often use elevated radials, giving the antenna system more independence from ground. Have a vertical that I’ve used in the past; it has 6 elevated (about chest-high) radials, emanating from the chest-high feedpoint. It beaves well. It is a surplus military, several-section, self supporting whip, about 13+ ft. high; resonates around 20m; take off one section, and it’s close to 17M; take off 2 sections and it’s close to 10M. Regarding number of radials, more are much better, with diminishing returns, but you only need 1. Also, at frequencies above 8 MHz, vertical antennas are affected (lobes and nulls) by nearby vertical things, e.g. trees.
In the latest issue of QEX that arrived here today, there is a design for a ground independent wire vertical. It is compact but requires a glass fibre mast rather than a carbon fibre mast.
Might be useful for DX but more complicated than an end fed wire.
A description of the antenna might perhaps be better than a mere mention of an article in some issue of QEX - there are many who do not subscribe to such journals. How does that antenna differ from other verticals?