With my wife’s health getting better, I’m planning next month to possibly activate some summits in Wisconsin and Michigan.
Currently I am using a G5RV-Jr. (40-10meters) in an Inverted Vee config. with a 31 foot Jackite pole. I feed my FT0817 through a MFJ-971 tuner for matching.
Has anybody attempted to put a 2 meter signal out on a G5RV with the antenna tuned to about 7.100 Mhz. and 144.200 SSB fed through the tuner to the antenna?
I’d like to try some 2 meter BUT don’t necessarily want to carry another antenna to accomplish this task, if possible.
I’m currently at 1298 Chaser points BUT ONLY 20 Activator points SO I’m really behind in paybacks to the group!
Not something I’ve tried, or am likely to, it just seems easier to bodge up a resonant 2m antenna. It would be really lossy I think, as I imagine you have coax in your G5RV. I don’t even think the tuner would cope with such a match, but then I don’t use tuners, so not the best person to comment on that.
I’m sure you could quite quickly come up with something suitable for horizontal polarisation that didn’t weigh much at all. Maybe a simple dipole from light wire with some string to peg it out from your 31 foot pole? Even a lightweight yagi is quite quick, loads of plans on the internet for one of those.
Having said all that, I did discover that my 20m inverted vee was resonant on 145.6 Mhz, maybe 21/2 wave. I used it to open the close by repeater by mistake once, antenna switch faff.
My full-size G5RV, set up as a doublet with 300 ohm ribbon all the way to the rig, just happens to be resonant on 50.150 with an SWR of 1:1. It has a pretty high SWR on two metres but I suppose this could be brought down by trimming the feeder, avoiding losses in a tuner!
73
Brian G8ADD
PS You are not really behind in “paybacks to the group”, it is a symbiotic relationship: activators need chasers, chasers need activators, a perfect partnership!
In reply to KA5PVB:
Hi Chuck.I think I may be thinking of sacking the ATU and making a linked dipole for the bands that I wanted to use including 2 metres 73 Geoff G6MZX
A low SWR tells you that the power produced by the transmitter is being used efficiently. That does not guarantee that it is being radiated, as Andy points out, it may be being dissipated resistively. On the other hand, though, in a simple doublet without an intervening tuner it is hard to see much chance of this happening, how lossy can 300 ohm window ribbon be? The real concern would be where that power is being radiated to? How much is warming the ground or the clouds. For that reason, although I know from experience that a long wire/counterpoise arrangement works really well on six metres (where the sky wave is important), I feel that a more conventional antenna on two metres would be prudent.
When I have been desperate to contact another summit (usually for a complete) and have no 2m antennas with me I have used my HF antennas.
I did model my fan dipoles for 2m (just for fun) as the SWR was low-ish, the pattern looks like a demented Hedgehog with loads of lobes going in no useful direction.
The first successful amateur moon-bounce experiment used a rhombic antenna, so big wire things can radiate efficiently on 2m. How practical they are for SOTA is another question, but I wouldn’t rule them out completely…
I intended to reply to the thread generally, not challenge your comments - finger trouble on my part!
There are many summits eg close to the west coast of UK, or hemmed in by higher ground, where the ability to rotate a beam through 360 degrees is of limited benefit, and I have wondered whether a wire V beam pointing eg South East might be useful on 4m…
The idea seemed pertinent to this thread…
I remember that ZL to G moonbounce success: the guy was using a large terminated Rhombic pointing at a small area of sky near the horizon, where the moon would pass through providing a brief window of opportunity. Though I don’t remember anything being said about it at the time, I suspect that he was also using a beneficial ground reflection. This was an eminently successful specialised use of a wire beam, and there is no doubt that a similar beam “could” work for SOTA as long as you had a suitable centre of activity to aim for - or perhaps even two, as an unterminated V-beam or rhombic is bi-directional! For my money, though, it is too much trouble to set up, needing three masts for a V-beam or four for a rhombic - if a reliable wire antenna with gain is needed I would rather think in terms of a broadside array or Sterba Curtain, at least it only needs two masts!
An achievement indeed, Richard! Perhaps it was ZL to EU, it was a long time ago, now, I remember the article about it, in the old Short Wave Mag(?), but don’t have it now to refer to. What was the ZL that you contacted using as his antenna?
That sounds like a bit of a monster! Chicken wire on a framework former? I experimented at one time with the idea of a cylindrical paraboloid since a rectangular sheet of metal supported at two edges flexes into that shape, but it came to nothing - we moved to a house on the north side of a steep bank where the moon was rarely visible, and I’m afraid I lost interest after that!
Firstly on the topic of convenience/imperative I was once forced to use my G5RV on 2 m SSB out of desperation after 40 m failed to yield 4 summit contacts one Friday morning. I was able to work three stations on 2 m SSB within 50 km - all well set up and line of sight. If I had been farther out of town I would have had a failed activation. The G5RV is not a 2 m antenna and is pretty much rubbish on anything other than 80/40/20 m. Only use in an emergency on 2 m.
After that I resolved to be better equipped and mounted a pair of “rabbits ears” on a piece of plastic. The dipole length can be set for 2 m or 70 cm and used in V or H polarization. Much better than using the HF antenna and only a foot long and 1 inch diameter (quasi imperial units for our W friends)- add as much coax as needed and tie to mast or ski pole/walking stick or hold in your hand. I have worked over 200 km on ssb with the FT817 with this. I now carry a dual band whip and an elbow connector to fit the FT817 for short range vertical polarization contacts. The rig likes it better than the G5RV which has been retired in favour of other lighter antenna such as my croclink 40/30/20 dipole or a tuned doublet.
On the slightly off topic line:
In the 1960’s Ray Naughton, VK3ATN (SK) built a stacked rhombic array for 2 m and worked into the US many many times on EME using 150 W dc input, CW. The array was big even for 20 m and crossed a public road - he had a farm outside Birchip in NW Victoria. It used four large steel towers which he built himself. I think he started with two stacked rhombics and went to four stacked. Approvals? Well it was the 1960’s, he owned the local radio/white goods shop, a local pub and was shire president.
Definitely not SOTA stuff as part of the array would be outside the activation zone on most summits, assuming you could recruit a battalion of strong bearers to carry it there and erect it. I’ve heard recorded audio of his contacts and the signals including echoes were easy copy!
Now any whippersnipper can put up a 10 element yagi run 100 W and do EME with JF65. Can’t hear the signal but there’s the text on screen! Harrumph!
