Hi all i plan to do all 8 summits in my local area (Scottish Boarders area)before the end of the year.
To date i have done 3,using only VHF/UHF with my sota pole and small 3 ele beam. next summit on my list is G/SB-010 Housdon Hill however after reading reports from other people who have activated this summit they tell me i may struggle to activate this one with my VHF/UHF set up due to it being surrounded by the cheviot to the south and other hills to the north.
The last thing i want to do is get up there and fail to get the 4 contacts needed to activate it.
So i have decided to use an icom ic-718 and icom AH-4 long wire tuner to make life a little easier for me.
What i would like is some advice on wire antennas,what sort of system do other people use when on top of a summit??.
My plan was to 1, either pull some wire through my sota pole (8M) and use the AH-4 tuner at the bottom of the pole to tune the wire (Vertical style) or 2, Helically wind some wire onto the pole vertical and them make some sort of inverted L antenna ???
i would like to use 80m & 40m in particular so i can make some inter G contacts
The icom AH-4 tuner will tune these bands with as little as 7m of wire so that won’t be a problem.
Any ideas of wire configuration would be great
thanks in advance Keith M1VHT
In reply to M1VHT:
I’m also principally a VHF and up operator.
For HF, use dipoles in inverted V configuration supported at the top of the sota pole so you don’t need to bother carrying the matching tuner. Just keep the ends off the ground (I use a couple of those green garden canes) by having string attached to the ends of the dipole to peg them out.
You can knock working dipoles together very quickly with a bit of plastic covered wire and a connector block at the end of a piece of coax. I also use a choke balun (fancy name for a bit of feeder coiled up at the feed point) - lots of web references for that.
Have fun! If you get spotted you’ll find you get lots of HF chasers …
for a popular design. Of course you don’t need to make one of
these for all the bands just the one’s that interest you. Powerpole
connectors are not compulsory. For best results tune using an
antenna analyser while constructing - but in your case you might
as well use the ATU in the field as no dipole remains tuned once
Low dipoles such as the above tend to work via NVIS making them
ideal for inter-G work. Expect to work 100-300 miles in daylight
on 80m if condx good. On 40m 300-1000m in daylight.
Vertical antennas are good for DX but may require additional guying
in high winds. I’m sure others on here will give you some pointers
as to what works best.
You’ve searched the archives on here for what people use? If not, go and do that first as there is a wealth of info, including designs, pros and cons, sources for the parts etc. That saves everyone repeating themselves. From there, if you’ve got specific questions about then ask again and you’ll get lots of replies.
I’m not an expert by any definition of the word when it comes to HF antennas and propagation, but an 80m or 40m vertical is normally considered for DX work. i.e. low angle of take off and is unlikely to be the best choice for inter-G working. But you would be best getting that confirmed.
Another point, the AH4 manual says it must be grounded. How are you planning on achieving that effectively when in the field?
Linked dipole and leave the tuner at home. See John GW4BVE’s instructive pictures below…
I made my first one before I saw John’s and when I measured what I had made my measurements were exactly the same. I tuned each section before adding the next for the usual SOTA frequencies and it covers all the bands with reasonable SWR anyway but works best on the frequencies you tune it for.
I assume you are intending to use SSB. If you intend to use both SSB and CW then bear in mind that a dipole on 80 is surprisingly narrow band, and the centre frequency will be affected by site conditions. If you decide to follow the advice to use a dipole you will need to experiment with the dipole before committing yourself to an activation, and remember that it is very long on 80 metres!
The wire and tuner method will work well for you, but I suggest that you use the wire and pole in an inverted V configuration, this enables you to get more wire up in the air and it is more NVIS friendly than a vertical. It would be an idea to tune against a counterpoise, which needs to be no more than several metres of insulated wire lying on the ground. Winding a helical would use up valuable summit time. One elegant suggestion is to use the inverted V as two of the three guys to support the mast. I would peg each end of the wire, adding a few feet of nylon cord between the ends and tent pegs to keep the ends away from the ground.
I suggest you look up the W3EDP antenna, a few of us use this design for SOTA, it has the benefit that you can change bands very rapidly without having to get up and put in or take out links in a link dipole, and the tuner is simple. The dipole enthusiasts claim that the tuner is lossy, which is not necessarily so, but in any case it won’t be any more lossy on the hill than in your shack! On the other hand, it is extra weight, although mine weighs less than a pound in old money. Another idea to explore is a doublet using 300-ohm ribbon for the feeder, a doublet slightly over or under the resonant length for 40 metres will radiate reasonably on 80 metres and very well on the higher bands. This will need a tuner with a balun or a balanced tuner.
In reply to M1VHT:
I use a very light (360g) inverted V antenna (for 40m and up) named ‘Yoyo’ on a 5m pole and with a RG174 line.
Neither a balun nor a tuner is needed if you test your antanna in your garden before. You just need to find and mark the required length of both legs.
Hi All thanks for your replies and great suggestions for my wire antenna,
i particular like the inverted V idea and using the antenna as a guy rope also
the mode will only be SSB.
will give it all a think over and let you know of my chosen method
regards Keith M1VHT
I use a very light (360g) inverted V antenna (for 40m and up) named
‘Yoyo’ on a 5m pole and with a RG174 line.
Neither a balun nor a tuner is needed if you test your antanna in your
garden before. You just need to find and mark the required length of
Yoyo antennas are great and you can buy winders from caravan shops or off eBay at about £2 each as they are sold as camping washing lines. Just mark off each band with a different coloured piece of insulation tape. No tuner required!
The down side as compared to the linked dipole is that you have to relocate the ends of the antenna every time you change bands. It works great on summits with a straight wire fence as support if you use carabiner clips on the ends, but would be a pain on most summits. Still a fun antenna to try and great for a suitcase antenna for holidays.