Open-Wire Line for Antennas- Using Open-Wire Line in “Forbidden” Places
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- čas přidán 3. 04. 2024
- Speaker/Presenter: John Portune, W6NBC
Documents (including slideshow): www.dropbox.com/scl/fo/ovp65b...
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What an amazing jewel of a video! Absolutely fascinating in all aspects! Thanks so much for making and posting this! Loved it!!!
Thanks for your comments --- Keep em coming (smile).
My first antenna as a novice (KN7REX) was an 80m-10m dipole using a 450 ohm ladder line. I ran that to a homebrew antenna tuner, where I made the 50-ohm coax connection from the transmitter. That was in the early sixties. I also worked for a local electronics supply company that sold already-made up 450 ohm ladder line along with coax, etc.,.
This presentation brought back lots of great memories... Dan / K7REX
John is an absolute TREASURE TROVE of information. I've learned so much from all his presentations. Thanks for sharing them on the platform! 73! W5ODP 🙂
Our pleasure!
Ya gotta give them old hams credit. Them old ancient hams of the early years of Amateur Radio probably forgot more than the newer hams will ever learn, and that goes for John too. Hats off to all of them.
Greetings from Sweden 🇸🇪
You, Sir, just got yourself a new subscriber and a thumps up 🎉
Absolutely True philswede. He converted me as well.
Excellent Presentation - 600 ohm feed line user here. I regularly violate many of those "rules" and concerns. Thank you. Paul - KC5CYY
Thanks for the video. Great information. I would say one aversion to using open wire transmission line is most amateur radios/transceivers are 50 ohm and most commercial purchased amateur antennas are 50 ohm. To use open wire ladder line transmission line means I have to convert at both at the transmitter and antenna. So it means an extra transformer at each end. And since all test gear is 50 ohm native, it means having yet more transformers to match the transmission line. This to me is the largest aversion to using open wire transmission line for amateur radios. Thanks again for your time and effort for the tests and filming you have done.
Thanks John, and thanks RATPAC!
Just saw your informative bide on Open Line.
i wouild like to see your results of use ladder line in the same four indtallstion situation, but WITHOUT the grey foam conduit. Just repeat with ladder line unprotected, to just how bad would the loses be.
- Paul
worked on lots of ships with remote tuners fed by rg-213 to wire and verticle glass antennas 2-21 mHz without issue worldwide (ie: antarctica to north america) with 500 watts or less. At the same time worked the world from those ships on the ham bands with poor multiband verts and 150w or less (10-20 M due to antenna) fed with high loss coax rg-58 or 8x and was very succsesfull. I spent time at the CG commsta next door to KPH (NMC) back in the 70's and got to admit, wish they would have let us play ham there LOL. As I recall they had 10kw+ ssb and 2-4kw MF cw. As best I recall the hf antennas where rhombics aimed west and sw, not sure about the mf ones. enjoyed your video, thank you 73
Outstanding presentation, thanks
Fascinating findings.. Thank you so very much
Thank you for this presentation. I enjoyed learning more about this subject.
Glad you enjoyed it!
The information is interesting. If you could show the return loss of the unencapsulated open line in each of the situations you demonstrated, the differential data would be even more compelling. Using water pipe insulation provides a continuous "stand off" regardless of the environment that the open line is routed through. Quite clever. However, in my situation, the insulation increases the visual impact of my entire antenna system. Using the old-fashion TV stand-offs and other means to insulate the open line from its environment may result in less of an eyesore, in some cases.
Big open wire feed line fan here. Thanks for the information and I suspected this to be the case. When you go to a true 600 ohm feed line the conduit is going to get pretty big for burial! I always wanted to make a circular multi-feed open wire feed system inside of PVC pipe. You could even pump dry air into it like the big broadcasters do with there hardline coax. 73, KF0BBU
Good video Mike. Did you by any chance evaluate whether Zo was affected by the foam. I would expect an increase in capacitance per unit length and a corresponding drop in Zo. This isn't a loss consideration but would create an impedance bump.
We might even BUILD our own open wire transmission lines !!!
thank you
Would running power and using your water pipe sleeve affect the losses you measured over the different materials? I would think running more power increases the field around the transmission line, possibly having an effect on swr.
How could one use open wire line for feeding say a Dual band vertical? Would you need 2 9:1 baluns?
Interesting. Whilst I certainly remember 300 ohm ribbon (used mostly inside) and 300 'Ladder' wire (mostly used for long runs up towers for TV antennas around here (fringe area at the time), I've never seen 450 or 600 ohm line in use in this country. I think the reason for the rise of coax is partly that rigs seem all to 50 ohm outputs to an SO239 these days and coax is unaffected by weather, so we live with the loss, particularly on HF where it's less of an issue. 300 Ohm ribbon UV stablised (black, not the clear stuff) is almost unavailable here now and the ladder wire which is far better for outdoor (being solid copper) seems to have completely disappeared. There were issues with this too, for some reason galahs (common native parrot) seemed to love chewing on the plastic separators, which could result in it becoming just wire in the span of under a year. To a lesser degree, they attack coax as well, the usual solution being to put it through garden hose (UV stabilised type) to protect the cable from them. Galahs used to wreak havoc on the VHF Collinear Arrays 2with masthead amps we used for TV antennas (on top of a 30 to 40 foot tower) by perching on the elements, often in flocks, which sometimes broke them off at the plastic joiners and sometimes chewing on the phasing array plastic separators to the point it was just bits of bent or broken metal hanging in mid air. Towers were so common here (in Regional South Australia) to get TV from the 50's to the early 2000s when digital came in and local repeaters for the major networks finally were installed here, that there were streamlined approvals for construction, which remain, as long as the tower and the foundations are done as required and the local council inspects the concrete foundation and mounting j bolt before the concrete is poured, its a rubber stamp job and there are literally hundreds of towers (now obsolete for TV reception) still standing. It's become something of a hazard in fact, as they were made of 2 inch water pipe and when the galahs ate the cork caps, they'd fill with water, and over the years, if the base had been 'buried' by well intended gardens built around the base, the tower would rust out at the base and a strong wind would push it over, often onto rooves or power lines. Still have a few old towers fall over in storms every year, so people are gradually getting rid of them or cutting them off at roof height because they have a modern UHF antenna for the local DTV services on them. Just TV antennas here could get complex. There were often 3. A VHF High Band collinear at the mast for getting TV from the state capital roughly 100 miles away, feeding a masthead amp, powered from the ground, sometimes with coax, sometimes ladder wire. Then a VHF Low Band yagi for the two local LB VHF stations about half way up the tower and later a UHF Yagi for the SBS service was added, all fed to a three way filtered coupler, to which were usually added attenuators for the very strong local signal to stop it getting back up to the masthead amp and causing it to clash with the weak HB signal. It's much simpler now and one UHF yagi at roof height is perfectly adequate. Old 'boosters' were something of an RF problem as they would sometimes turn into noise generators as they aged, long after they were actively being used and this could create interference issues for HF particularly as they'd sometimes blot out entire parts of various bands with noise. Thanks for the lecture, it was interesting. 73 Geoff VK5GDR
DX Engineering sells 300 ohm window line. I run 180 feet of it to my 160 meter doublet with fantastic results. Low loss on all the HF bands with an MFJ-998 autotuner in the shack.
@@Ragchewer Ok, thanks, I'll look into that.
It's been a LONG time but when I lived for a year with by grandparents in rural PA in he 50s, a few people did what hey would get get television. Most had a roof top antenna with the 300 ohm flat stuff. But I say one installation when the antenna was about 3/4 of the way up a hill and there was 600 ohm open wire (with plastic links every 8" or so leading to the home at the base of the hill.
@@GilmerJohn Open wire line is actually less lossy than coax by a significant amount. More prone to picking up extraneous crap, but less lossy. Still a lot of towers here, no longer needed, but a few fall over every year where the legs have rusted out at the base.
In the conduit could the wire have coupled to the conduit and actually radiated? That radiated power wouldn’t reflect and might account for the loss measurement discrepancy.
I have a question for you. I am going to take my 7300 to a park tomorrow with the Wolfriver coil 17-foot whip. I will be on a deck made of fiberglass. Will my antenna see the radials as elevated radials.. WQ9V
When does the video start?
You say that the line needs to be properly terminated, yet people ask about using open wire 600 ohm open wire directly to a dipole and you don't flinch. Your transmission line is centerpiece to your transmission system. It must be matched at both ends. If you start with a 50 ohm transmitter, you need to use a 12:1 at the input to your open wire 600 ohm line. That may be after a 50 ohm line of some length. If you then have a ~75 ohm antenna, then you can utilize a 8:1 to match it at the dipole center feedpoint. This is critical to any successful usage of open wire systems. Especially at 160 meters where RG-58 isn't really all that bad, it would probably outperform a mismatched 600 ohm feeder.
The high power open wire at the first looked like an open wire coaxial cable with the center conductors tied together and the outer conductors tied together. Probably 50 ohms.
Why didn't you properly load the test arrangements rather than shorting them on the ends? This made no sense to me. Return loss is the amount of signal going out compared to the reflected amount. So if you have a lossy transmission line that takes 50% of your 100W and the antenna transmits 50W, your return loss will look very good at around 45 or so. We need to look at the amount of current actually accepted by the antenna in real tests. If we don't do this, we are hiding our real results.
You seem accomplished. I don't have a second class radio telegraph license. I'm just a school bus driver. N9XR
Ladder Snap is for 14 ga wire .....Not 12ga
Using TRUELADDERLINE with Balun Designs 4:1 Balun