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Dealing with rats nest 300 ohm twinlead ?

At present I am using a 1/2 wave 40m dipole fed with 300 ohm twinlead. It works very well on 7-21MHz through a BLT tuner. I have two homemade antenna wire winders which work well for dealing with the dipole wire and support line ends. However, the 300 ohm twinlead is proving to be a bit painful to roll up after every session. It might be overly long for a start but I want to keep it that way in case I ever launch the centre insulator really high!

The twinlead now has a “last” and winds into about a 6" diameter roll. I keep it stored with two velcro lines around it. However, any little carelessness on my part when raising the antenna and the roll tangles itself and I have to re-roll the whole thing starting at the centre insulator. I read somewhere that a circular plastic container can be used to house the twinlead but that only seems to be good for storage and not any real use when it does need to be unwound and raised.

Does anyone out there have any brilliant ideas other than me just being more patient ? :wink:

I see so many heroic antenna efforts… and yet, in my experience, it is so unnecessary. I abandoned such things as throwing things, insulators, feedlines of any kind… The top of mountains is generally rocky, little ground absorption, we have seen very little difference between an antenna wire laying on the rocks (see a post by KX0R) and being thirty feet up. I use an endfed halfwave #28 wire, part vertical, part horizontal which is generally about 15 to 18 feet up. The end of the wire is plugged directly into the radio (through a matching device that weighs less than an ounce. With it, I have worked DX around the world while running only five watts. I doubt if anything else would perform any better. A directional antenna would perform better but only in one direction. Set-up and tear-down typical under five minutes. Total weight of the station including twenty foot pole is under one pound. Keep it simple! 73 Fred KT5X (aka WS0TA)

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Hi Larry,

I’m a 300 Ω guy as well and I’m still looking for the ultimate solution. My present tactic is to use an AC cord winder.

https://www.amazon.com/dp/B0037W5W2O/ref=cm_sw_em_r_mt_dp_U_rSVICbKDQQB0H

This particular one is bigger than necessary for the 50’ of 300 Ω I carry up the hills so I just cut off the ends a bit. It lasts a few years, but breaks eventually. I’ve thought of using the plastic thing as a template and making a similar widget out of aluminum, but I haven’t talked a welder into giving it a try yet.

For winding I turn the thing end over end to keep the balanced line as flat as possible which makes the next unwind a little more tidy.

Jason

When I first started activating SOTA peaks with my 5W ATS-3B radio, I wanted to have the best signals possible, so I carried about 40 feet of 450-ohm window line and a very small telescoping fishing rod, with a small spinning reel. I cast a pilot line over a tree, then I brought up a larger line, and finally the antenna - usually a 40-meter half-wave dipole fed with the window line and a BLT-style tuner.

I already had experience with QRP gear in the mountains, and I had solid SOTA activations right from the start. The BLT tuner tuned the 40M dipole on 40, 30, 20, 17, and 15M, with excellent results. The flat window line rolled up into a neat coil, and it isn’t especially heavy, so I might have continued doing SOTA that way for a long time.

Since there are no trees above about 12,000 feet elevation here in Colorado, I used a Black Widow pole, almost 20 feet high, to support a 20M dipole, which I fed with a twisted pair of teflon wire. This antenna performed well on 20M, but it was obviously lossy on 40, 30, and 15M. The pole wasn’t rigid enough to support the window line, or 300-ohm line, so I never tried those with the pole. A 40M dipole seemed equally impractical. I certainly didn’t want to use a larger pole up there!

I knew that Fred KT5X and some other leading SOTA activators were using light poles with thin end-fed wires, and I traded emails with Fred - we discussed his methods. I wasn’t sure that an end-fed antenna so close to ground would radiate as well as a center-fed dipole. My Eznec models told me that the dipole had a better pattern. The turning point came quickly on a local summit above 12,000 feet.

I put up the 20M dipole using the Black Widow pole, on the rocky, exposed summit, in a huge field of sharp, loose talus. With a dipole you have three wires to manage:

One leg of the dipole
The second leg of the dipole
The feedline

You also have to support the pole, somehow, in the talus, as there is nothing like a tree to help out. If it’s windy, the pole may not behave or even stay up, unless you guy it to the rocks. This means you may have to manage 2 or 3 guy lines, in addition to the three wires hanging from the pole. Everything wants to tangle, or to move to the wrong place!

The talus kept catching my wires as I struggled to lay them out in the breeze - I realized how hard this would be in a stronger wind - the kind that we often have above tree-line! Trying to balance, not fall, and function in the loose talus and thin, breezy air wasn’t easy, despite my years of experience in the mountains. Eventually I solved the puzzle and got on the air, and I had a nice activation, at least on 20M - but the feedline mismatch was too great on other bands, and I only made a few contacts once I quit 20M.

Earlier that year I had taken a QRP radio out in the woods, just to see if I could make any contacts with an end-fed antenna and a BLT tuner. There was a foot of melting snow, so I used snowshoes to hike into the saturated forest near my home. After casting a line about 40 feet up in a pine tree, I raised the end of a 65-foot wire, and then I tied it off to a stump at the lower end. The wire ran diagonally up toward the top of the tree. It was a half-wave on 40M, and a full wave on 20M. I got on the air, called CQ, and made a couple of rag-chew contacts on 40M and 20M.

I was impressed with the simplicity of the “system”. I got the big wire up high, despite deep, slushy snow everywhere; I made easy, conversational CW contacts on 20 and 40M CW, with just 5W. What really nailed it was that one of the operators sent me an email with a digital file - a recording of our contact. I couldn’t believe it - it sounded just like a contact from another home station - except I was sitting out in the woods in a foot of wet snow! My signal was fine - solid and Q5.

My end-fed experiment, done before I ever started SOTA, stayed in my head. After I was up at 12,000+ feet struggling with the wires and lines in the windy talus, I thought about how I could have set up using an end-fed wire. One wire would be so much better than three, all trying to get tangled in the wind. The pole would stand higher, and the one wire could serve as one of the guys - it was so logical. The same wire would go down the pole to my tuner, and I could even sit next to the pole to help steady it. There would be no feedline to unroll and connect. Much more important was that I knew I could tune the wire on any of the popular HF bands, and there would be no feedline loss, as with a mismatched dipole.

I did many experiments, mostly using different lengths of wire, some with counterpoises, and some without; I always activated on multiple bands. The one thing that needed improvement was the BLT tuner - it was struggling to match the roughly 3000-ohm impedance of the end-fed. I made a little high-Z tuner to connect between the BLT and the high-Z wire. It stepped up the impedance and allowed the BLT to share the matching at a lower impedance, where it was more efficient, from band to band. The two-stage approach was effective and easy to use, but it wasn’t ideal. After a couple of years of two-stage matching, I devised a single multi-band tuner to match high and low-Z antennas, to do the whole job, with fewer parts. It was simpler and easier than anything that I’d used previously, and I’m still using it. I just wrote it up on another thread on this website! It’s the “KX0R Tuner”.

In summary:

  1. A single end-fed wire is more practical and effective to use for SOTA activations than anything else we know about.

  2. You can use your limited time on a summit any way you choose, but many of us prefer being on the air and making lots of contacts over struggling with complex antennas, feedlines, and heavy poles.

  3. An end-fed system is safer than a traditional dipole, because it can be erected and taken down much faster. In windy, cold, or stormy weather, the advantages become incredibly clear!

  4. Reducing weight and complexity buys you time and energy, especially at high altitude, when you don’t have enough of either.

73

George
KX0R

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I’m using an 11.1m length of 300 ohm twinlead as feed to a zs6bkw doublet (28m). I centre feed it, suspend the dipole/doublet at the top of a 7 or 10m telescopic pole. I installed 4mm banana sockets on the antenna feed point and plug the corresponding plugs into that, tape the twinlead to the pole at the top and sometimes lower down. this antenna works with a tuner on 80/40/20/17/10 without leaving the radio.

to carry the twinlead I usually roll it up to a diameter of about 8 to 10", whatever fits into my backpack. Just tonight I changed that arrangement and I am trying one of the sotabeams wire winders for the ribbon. it certainly rolled up well and with the figure 8 winding method, it should come off the winder without any twists, well to be precise, without any more twists, because I don’t care about a few twists in the feeder, it helps stabilise it anyway.

I roll up my antenna wire on a fishing casting reel about 8" diameter. this packs in quite neatly and I almost never have wire tangles to deal with. the wire is dx-wire type multistrand with fibreglass inside a tough insulating material (very tough. I made a linked dipole with this stuff in 2013 and expected it would only last a year, no it is still going strong).

hope this helps

73 Andrew VK1DA/VK2UH

Thanks to all above who responded. To Andrew and Jason - yes I am thinking I may eventually need some sort of winder for the feedline unless I am more careful unravelling it as needed on the summits. I am trying to get away from more bulk and weight so might try two more attempts without some sort of changes to my system and see if I can’t deal with it better!

To Fred and George: thank you both for your obviously highly experienced insights into simpler antenna systems. I agree that on a very rocky, treeless summit, in less than ideal conditions, your simple end-fed antennas are probably the way to go. Over 20 years ago now I do remember doing a couple of outdoor tests in North Wales between a half wave dipole, a St. Louis Vertical and a simple end fed wire and the dipole always came out on top - but that could hardly be considered a proper scientific test as it was only with a couple of stations. It does not take much of an antenna to get a contact. I remember in the early 1970’s having a QSO with a station over 1000 km away, in the evening on 40m. I was at the time testing an 80w homebrew transmitter using a light bulb as a dummy load in my basement!

As a QRP station I always try to never forget that it is not really me doing the “heavy-lifting”. Most of the time as SOTA HF activators we are contacting base stations running significantly more power into often high gain directional antennas. Actual QRP to QRP contacts in this solar cycle low are quite rare. So those “base stations” can often hear even the most meagre signals from basically poor antennas.

The nearby “summits” in my neck of the woods on southern Vancouver Island are mostly under 1000m and tend to have at least a tree or two perhaps not right on the summit but very close by. So the dipole works well for me and I can have my antenna and station set up in about 10 minutes if my first throw into a tree works out. I will be considering a simpler pole fed wire something like you’ve described when I graduate to the higher more Alpine summits of the Interior Range here !

There are so many multiband qrp ! antennas that work well in use with an antenna tuner and are really small

For example the NorCal Doublet Antenna - http://www.norcalqrp.org/norcaldoublet.htm -
… or the Twisted Hille - 2x 6,5 m (some use an old category 7 cable with the twisted pair as a feeder) an fix it with this knot:

73 Armin

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I can recommend the use of computer ribbon cable for antenna and feeder à la Norcal Doublet - really light and very durable (though getting a bit expensive these days - cheap supplies of ribbon cable seem to have dried up :-s)

I use an “extended” version - legs about 17m long - for 80/60/40. Often achieving 50+ activations before the wire breaks (always at the point where the legs become the feeder - a gentle “tug test” identifies an antenna that has reached the end of it’s useful life, though a field repair is quick and easy).

Easily tamed for packing up by winding each leg on a wire winder, then placing the two winders together and wrapping the feeder section round both.

Edit 2 - another tip, maybe original never seen it anywhere else… I use screw-fix 4mm banana plugs on the end of the feeder. Strip 25mm of the insulation, and wrap the wire round the bottom 5mm of insulated wire then clamp the wrapped section with the screw - holds really fast and doesn’t break, not had one come adrift in the field ever!

73 de Paul G4MD

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See pics. Still trying to figure what Beetroot, Lettuce and Tomato (BLT for hamburgers) has to do with antennas.:rofl::rofl::rofl:


73
Ron
VK3AFW

Bacon, lettuce and tomato - a sandwich in the UK, reputedly developed by Clement Freud for British Rail in the 1980s. And equally relevant to antennas :rofl:

It sounds like you have been doing much as I have been doing, but it sounds like you have been rolling into a much smaller coil than I do. Below is a picture of my 88’ doublet with 6-7m of 300 ohm window line. The coil is conveniently sized to fit within a one gallon ziplock bag. The inner coil is 6" but the outer coil is 9". This doublet has probably seen hundreds of activations and the window line definitely has a bit of a set, but I can’t remember the last time it caused any issue. The first thing I do when setting up the antenna is toss out the coil of window line and it normally unfurls without any issues! I don’t know if the direction of coiling makes any difference but when packing up I wind up the legs on the winders and then holding the winders between my knees, I start coiling up the feed line from the center isolator (instead of rolling up from rig end of the feed line).

73, pat - KI4SVM

Pat: thanks I will try your suggestions. Perhaps you are right - I might need a much larger diameter coil and a lot less of it. I probably have over 20m of the stuff as well, so as I said above I think I need to reduce the length of feedline - I am probably never going to launch the centre insulator too high anyway…

Yikes! :upside_down_face: I thought I had read 7m somewhere. I can see how 20m of the stuff would be difficult to handle. My window line is sized to come right down to the base of the mast that I normally use with no extra. If I don’t use my mast or can’t put it all the way up, I try to find a branch to keep the extra length off of the ground (not sure if that is so important on most summits). What do you do with the excess feedline?

73, pat - KI4SVM

…unbelievable what makes people haul on the mountain …

ok - there are sherpas

I use 26 awg cable and fix it this way

great video - thank you Ignacio

73 Armin

Pat,

When I used larger window line, 420 ohm type, I used about 10M, maybe 35 feet of it. I coiled it flat like you do.

The window line, whether 300-ohm of 420-ohm, has lower loss than the TV-type 300-ohm ribbon feedline.

If you use 20M of feedline, you have double the loss of 10M of feedline. If the antenna is resonant and matched to the Z of the antenna, loss will be minimal - but if not matched, such as a 40M dipole running on 14 MHz, the loss on the line goes way up. You don’t want extra feedline for sure.

All by balanced lines have banana plugs and jacks on them. They can be plugged together like extension cords. A 20M feedline can be broken into two pieces with banana connectors, so you can use either 10 or 20M, and not carry extra when not wanted.

73

George
KX0R

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