Date
1 - 19 of 19
Long wire
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I've done a good bit of WWW browsing, but no joy on this question...if I want to use a long wire antenna with my Yaesu 951, do I have to connect it directly to the radio or can I use a piece of coax between the radio and antenna which would let me get the antenna ouside my house? I do have a good tuner. 72/73 Doc K5OSA
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You'll want to connect it to your tuner. Mike kd5rjz
On Fri, Mar 11, 2022, 1:19 PM Mlike McEwen <k5osamce@...> wrote:
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Mike Polia
I assume you are talking about an end-fed longwire antenna? Are you intending to use it on a single band or multiple bands. Single band is easy; a "fixed setting" tuner would be just fine. You don't have to adjust it and can mount it anywhere outside. Multiband is more problematic since, ideally, you want the tuner to be where the coax transitions to the wire. If you can use an autotuner that might be the best solution depending on the location of the tuner outside or in your attic or wherever.
Is there an issue with extending the longwire right up to your operating location in your house? Mike AB1AW
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Matthew Halsey
Or use a 9:1 balun with coax to your rig.
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Matt KC3OIV
On Mar 11, 2022, at 7:37 PM, Mike D <vfd.ninja@...> wrote:
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Dave Benson
Doc- You can use a length of coax between the rig/tuner and the wire antenna. Shorter is better, because the combination of line length and high SWR can add additional loss to your setup. In typical installations it's not a concern., though. Be aware that the coax may be serving as a counterpoise. That means it will have RF current on the outside of the coax and across your rig. Your equipment and potentially you are actually part of the antenna. At higher powers, it's not unheard of to get 'bitten' by equipment in the shack. This stray RF may also cause flaky behavior with accessories like external keyers. If possible, you want a ground somewhere.- preferably at the antenna end of the coax, but that's not always practical. Copper hot-water pipes are often a good ground within the house. In a pinch, I've hooked to the cover screw on an electrical outlet, but it wasn't very satisfactory. My temporary shack was in the worst possible location in the house- right above the 200A service panel. Line noise was S-7 or more and could hear only 'Big-gun' stations. QRP contests were out of the question from that location. One more trick is a so-called 'artificial ground' if you run into high SWR issues. We're not there yet, thouogh. 73- Dave, K1SWL
On Fri, Mar 11, 2022 at 2:19 PM Mlike McEwen <k5osamce@...> wrote:
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Karl Schwab
With an ICom IC-706MKIIG, I have a manual MFJ-tuner (a model that feeds a random length wire) coupled to the radio via a short length of coax, and sitting right behind it. From the tuner, a 100' length of wire, out the window and up into the trees. A ground wire from the radio and tuner also goes out the window, directly to 3 ground rods outside that are used for my electric utility service. Works good for me on all HF bands running 100 watts. Simple and inexpensive. I probably would be more careful if I were to run 1kw. Karl/KO8S
On Fri, Mar 11, 2022 at 3:30 PM Matthew Halsey via groups.io <rftb_cowboy=yahoo.com@groups.io> wrote:
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Tim N9PUZ
You may be referring to what is often called a "random wire antenna". The best lengths to use are NOT truly random. Your tuner will probably most easily tune a wire whose length is NOT a half wave, or any multiple, on any band you want to work. For 80-10 Meters these lengths match well: 29 35.5 41 58 71 84 107 119 148 203 347 407 423 feet I've done this for temporary antennas and find that 84 ft seems to work best while being pretty easy to string up. I normally usea 9:1 or 4:1 UNUN to couple the wire to the coax. You may need to add a 1:1 feedline choke near your rig or perhaps where the coax enters the house. The coax between the choke and the 4:1 UNUN will usually work as your counterpoise.
On Fri, Mar 11, 2022 at 2:58 PM Karl Schwab <schwab.karl@...> wrote:
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Don, W9EBK
Doc, N9PUZ's advice is very good. I will add these things based on personal experience. Bringing the wire all the way in to the radio will work well for receiving. The problem comes with transmitting. The voltage some places along such a wire can be very high with as little as 10 watts. At 100 watts those voltage nodes can give you a serious burn or start a fire. OK, starting a fire isn't personal experience, but I've seen the aftermath. Put the wire outside, put a decoupling device such as a balun, Unun or isolator between the wire and the coax and use the shortest length possible of high quality, low loss coax to bring it to the tuner at the operating position. As for the balun ratio, try whatever you have, but I'd bet on the 9:1 working best. If you can add a counterpoise of any length, do so. Even 3 or 4 feet can make a big difference. 2 caveats: I have seen times where changing the length or height of an antenna like this even a few feet will change it's matching characteristics wildly. And, if the tuner just won't match it on a certain band or the tuning is ultra touchy it's likely that you are feeding it at a high voltage node on that particular band. Rather than mess up all the other bands by changing stuff, try putting a small high-voltage capacitor in series with the wire when you want to operate that band. Don, W9EBK
On Fri, Mar 11, 2022, 1:19 PM Mlike McEwen <k5osamce@...> wrote:
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Curt
Doc
Wonderful advice here already. The long wire is a classic antenna for shortwave listening, it's a bad idea except for specific lengths that Tim provides, and installation details from Dave. Most tuners are designed for moderate swr, sometimes limited to around 3.5 to 1. Determine how you can ground it from the tuner. Coax is usually a bad idea unless antenna is matched, so no coax between wire and tuner is advised. Curt wb8yyy
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Dan Presley
Another less used option but can be effective is the bazooka. This can be made with a half wavelength of coax. Basically it’s a half wave where the braid is removed at the quarter wave measurement,leaving the inner conductor exposed and the remaining intact coax section is attached to the radio. There’s variations on this,and of course you’d want to weatherproof it at the cut section,but it would allow you to run coax from the radio. Here’s a vertical variation,but you could certainly run it like an end fed say,at a 45 degree angle from the quarter wave cut.
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A few years back there was a version described in QST as a portable multi band antenna, designed to be deployed from an apartment window or balcony. I’ll try to find the month/year. Dan Presley 503-701-3871 danpresley@me. com N7CQR@...
On Mar 11, 2022, at 13:07, Tim N9PUZ <tim.n9puz@...> wrote:
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Excellent info...Tnx!
On Fri, Mar 11, 2022, 5:53 PM Dan Presley <N7CQR@...> wrote:
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My shack location dictates mounting the antenna about 20 meters from my transmitter and multituner...all of the suggestions I have gotten from you all have been VERY useful...73, Doc K5OSA
I assume you are talking about an end-fed longwire antenna? Are you intending to use it on a single band or multiple bands. Single band is easy; a "fixed setting" tuner would be just fine. You don't have to adjust it and can mount it anywhere outside. Multiband is more problematic since, ideally, you want the tuner to be where the coax transitions to the wire. If you can use an autotuner that might be the best solution depending on the location of the tuner outside or in your attic or wherever.
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Apply a 9:1 UnUn at the feed point, a 15' counterpoise, and as much coax as needed to the indoor tuner. You will be fine. Assumes a pseudo-random wire of 35.5', 41', 58', 84', or a few other non self-resonant lengths. Don't over-think this.
-Ted K3RTA
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Curt
Doc
I have recent qso with Ted on 80m, he copied my para80set during a 30 plus minute qso on 80m, and vice versa. So his somewhat shortened antenna works very nicely, so enlist his help until you are radiating. Yes an easy endorsement. I researched the rig I was using and found that Terry Fletcher built one of the original homebrew prototypes, the rig was then called the MAS80. So I hope 4staters continue to homebrew. 73 curt
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Sam Billingsley
I have heard lots of good advice but I’ll add my 2 cents.
I use an 84 ft W3EDP with one end directly through a window (second floor) connected to a manual tuner. No problems at all with QRP levels but RF bites at 100 watts. I have an outside counterpoise( one end grounded to the tuner) of about 30 ft long out the window and down towards the ground but not connected to a ground. My manual tuner is able to get low SWR. I.e. better than 1.5 to 1 on all bands from 80 to10 meters. I’m sure a modern Xcvr with internal tuner could do the same. Good luck with your experimenting. Sam AE4GX
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W6BOW
Sam,
Most helpful. Thanks. Your antenna set up seems quite similar to mine (potentially). Due to the size of my lot, I don't enjoy a straight 84 ft run from my second story window. Question: What is current thinking on longer, resonant or random lengths of wire angled at right or other angles? Does more wire necessarily improve antenna efficiency?
Curious.
Don
W6BOW
-----Original Message-----
From: Sam Billingsley <billingsleysam@...> To: main@4SQRP.groups.io Sent: Fri, Mar 25, 2022 2:01 pm Subject: Re: [4SQRP] Long wire I have heard lots of good advice but I’ll add my 2 cents.
I use an 84 ft W3EDP with one end directly through a window (second floor) connected to a manual tuner. No problems at all with QRP levels but RF bites at 100 watts. I have an outside counterpoise( one end grounded to the tuner) of about 30 ft long out the window and down towards the ground but not connected to a ground. My manual tuner is able to get low SWR. I.e. better than 1.5 to 1 on all bands from 80 to10 meters. I’m sure a modern Xcvr with internal tuner could do the same. Good luck with your experimenting. Sam AE4GX
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Lloyd Sumpter
I've always said the antenna equivalent of "there's no replacement for displacement" is "the more metal you have up, the better the propagation". I get better results from my G6RVjr (around 60ft overall) than with my Gap Challenger. And SWR is not nearly as important as folks think. Picking up
RBN's is the best way to measure propagation. Lloyd VA7LAS
On 2022-05-06 11:05, W6BOW via
groups.io wrote:
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Curt
Well more metal is a bit contrary to the original question, and he has some sound advice already.
I did overdo the metal once. I built a too large horizontal loop to fit the space I had. It had a wonderful signal on 20m to ZL. But it was a dud to Europe or Asia or South America. So it's possible to overdo it. SwR matters not for antenna but the transmission line to get the signal there. Coax is intended for reasonably matched antennas not random ones. When swr is high the coax becomes the antenna. And more is dissipated in the coax where it does travel. Curt
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Would a 9:1 matching transformer do the trick? I think that is what I used for my random wire antenna back in my SWL days. Worked fantastic. I could get Ascension Island BBC from the foothills of the Sierras in Northern California. Dave, KJ7WUZ
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