RANDOM WIRE ANTENNAS USING THF LDG 9:1 UNUNS
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- เผยแพร่เมื่อ 7 ก.ย. 2021
- The Random Wire Antenna is popular with Han Radio operators around the world. But how does it work, and does it work! Peter g3ojv, takes a look at it and relates his experience.
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hamradiostore.co.uk/ldg-ru-9-... - วิทยาศาสตร์และเทคโนโลยี
Thank you, Peter. Your explanations are so thorough I finally feel like I can understand these issues. I have both LDG 9:1 and the 1:1 choke. Your explanation of the counterpoise was most welcome.
I could listen to you all day long, please don’t stop the videos amazing
Well I must show this quote to my wife!
Wow! This is a classic presentation that everyone interested in end-fed random wire antennas and 9:1 ununs should view. I think it is Peter's best presentation, and may be the best available on the practical aspects of feeding and optimizng end-fed random wires.
Glad you enjoyed it!
This is the best discussion of both the random wire antenna and the unun that I’ve ever heard! Thanks!
Many thanks. 73 Peter.
I use 130 feet of wire on my endfed. People have gone to 203 feet and longer. That is what I have planned for my next endfed.
I have learned so much from you. Thanks for this great video.
Wonderful discussion, sir! Thank you for sharing your experiences and very helpful information.
Many thanks. 73 Peter.
Back in another life in the Royal Signals... the random wire was my best friend! We parked up in an underground area on a chicken farm during an xcercise. I was the only one with comms due using a coax out to a unbalun connected to a very long fence!
Sir, you’ve been the single most helpful source for me to learn from as I look into HAM radio. I’m a pilot and assumed I’d understand more about radio, but boy was I wrong. So, thank you and keep up the great work!
This is one of the best, most concise, and (most importantly) technically correct explanation for these types of antennas. Thank you! 73 from NJ USA 🇺🇸
Many thanks David. Good to hear from you. 73 Peter
I have two of these 9:1's and they work very well. For wire I found speaker wire is very cost effective and it comes in thin sizes that hide easy.
Hello Peter.. Thanks for this video, im sure my eyes didn't move while watching this one. Antennas, and especially cheap simple easy to erect antennas are very interesting.. I use a small 10m wire and 9-1 unun at 7ft high. Worked stateside and most if Europe quite frequently. Didnt know about the line isolator though. Fantastic presentation. Many thanks. Gary.
Bravo! Finally someone explained the basics of antenna design in an English I can actually digest. Thank you!!!!
Great to hear!
Thank you Peter, as usual you've given me a great idea...
You are very welcome
@@watersstanton I have now bought the very same 9:1, and finished my long wire project..Thanks for the inspiration Sir
Thanks for the video. I have had great luck with the random wire 9:1 antenna.
Good to hear
Excellent video Peter. You answered a lot of questions I had about both counterpoise and the 9:1 unun. 73
Glad it helped. 73 Peter.
Thanks, Peter! A very informative presentation to help with my portable 40m QRP station. You have moved my timeline forward to getting me on the air.
73-Allan KA3FBL
Glad it was helpful! 73 Peter
Your comments at 9:20 onward helped me better understand the relationship between low SWR and impedance. It stands to reason that the 49:1 is happy every time it sees 2450 ohms. Brilliant. Oh, by the way, we put quarter-wave end-feds on our rigs all the time. It’s called an HT, hi.
A well thought through presentation Peter. I use a 9:1 to some success, Brazil on 10w whilst sat in the garden. Yes I needed to use the tuner. A counterpoise or mix of radials are a must.
Many thanks Gary. 73 Peter.
Great video, Peter. Your opening _does_ sound like a Monty Python spoof, however.
Oh well hopefully no royalty problems.
Another great upload Peter! I'm a big fan of the 9:1 unun... although a bit of a compromise they make a great multiband antenna for home use when space is at a premium. My 9:1 configuration is a 22m radiator working against a 20m counterpoise, this let's me work bands 80m through 6m with some great results. As you point out the average vswr is approx 2.5:1 across the available bands but this can be matched via the transceivers internal ATU with no issues.
Thanks for that. 73 Peter
+1 on using a line isolator! Using a 9:1 random wire setup without one with just 10W on 15m made my PC do some very strange things, it was like there was a ghost in the machine. A bit shorter wire than yours worked well for close European contacts on 20m SSB with only 4W along just the top of a 1m high fence. Turning it into a sloper with the far end on 7m pole got me out to eastern Europe and one in to Asiatic Russia still on QRP SSB. I was really surprised what a bit of cheap wire could do. As you say, it will be good for portable or those starting out on HF on a budget. Mine is self wound, but found it fiddly to do so would probably just buy one of these if needed another in the future.
Maby thanks. That sounds like real ham radio! 73 Peter
This is a lot of information- but it helped me better understand some things before I set up my end fed random wave and unun. Thanks for explaining these details!
You're very welcome!
Nicely explained sir!
Thank you Peter
for the clarifacation on 9:1unun. I have one I tried to use on a short feeder cable of rg58 which is about 12ft long, I measured out 65 ft for the antenna, and I was using no ground earth, and was disapointed on some of the higher swr readings, and therfore thought it was faulty, the atu I was using is a edx1 from Alinco, my shack is in a stone building and a ground post is very possible in fact I have one to install now on watching this I am less worried I have been setting up correctly, The un un I bought was commercially made. I also made a line isolator on ferrite FT240-43 FERRITE TOROID from ebay and put it on the antenna side of the ATU. The radio I am using is ts130s
I have had some contacts on it, and now you have put my mind to rest on this situation, as I did not want to damage the radio. I intend now to watch more of you videoes and have suscribed
regards G1GDB
Hello Derek. Great to hear from you and get your update. Thanks fir the support. 73 Peter
Excellent Peter, I also run a 9-1 with a matching unit, good results on 40 meter, not so much on other bands, your video got me thinking, longer counterpoize and isolation unit, will give it a try, also I set up a portable, usually where I can find a good tree, thanks for the tips.
Thanks for the info. 73 Peter.
great video Peter really helpful, I will be trying this asap.. Gaz
Glad it helped
New Operator here. This was very informative/helpful & aligns well with what some others (Smokin' Ape) have talked about. I'll likely try this for my first HF antenna 📡.
73s
Welcome to the Hobby/
Great video. I am using the LDG 9:1 UNUN. I have it placed at the bottom of an inverted L. My feed line is a 100ft. RG 214 low loss. At first it worked fabulously from 80m to 10m. Then after a month or so all was lost. Upon inspection, the UNUN had filled with water. It's not supposed to do that. So they claim. Drained and dried out the UNUN and sealed. Mine wasn't initially sealed. Now it works again but it seems I do not get out as well as I used to. VSWR is very acceptable among the bands. Kind of confused at this point. I gave recommended the use of the 9:1 to several of my ham buddies a while back fo their end fed set up. Theirs have been working great. Man I love this hobby. Keep the videos caming. Have fun, stay safe and stay healthy.
Hi there. It is very easy to think after an antenna repaur that things are better ir worse. If the VSWR is the same as it was, then it is high likely that it is conditions. You could replace it with a brand new UnUn but I fear you may find it is conditions and not the transformer!
Thank you so much for this. This was the explanation of the "random wire" I've been looking for, for the last 25 years of being a ham! (Don't tell anyone.. LOL) 73's!
Thanks, Peter. What I love is the history and context behind the different antennas and products.. when explained, it really makes sense.. I must give one a go.. 👍
Glad you enjoyed it. Take care. 73 Peter
I did a test a few weeks ago. I ran out 25m of wire, connected to my Pl330. Checked reception over a wide range of freqs, the cut off 5m lengths and tested the same freqs. At 10m I reduced the length to 1m sections. Optimum reception seemed to be with 7 to 10m which is similar to the wire antennas supplied with these modern SW portables. Additional length increases noise and overload.. But the PL330 is a brilliant receiver.
I enjoy your down to earth comments based on considerable experience. Cheers.
Many thanks Ken for the information. 73 Peter
Well Done Peter, hello from Wisconsin!
Many thanks. Nice to hear from you.
Thanks for the counterpoise info, I think i asked for this in an earlier video, much clearer. I dont mind if your units are in feet or metres, we're all grown ups and all is ok so long as we know which.
OK,
Excellent stuff, this answered so many questions I've been searching for answers to (for hours I may add) in a succinct and interesting way. Will check out your other videos, many thanks
I just returned to thank you for this chart at 10:41 ..Thanks for the link!
You are welcome.
There is so much valuable information in this video. Excellentely explained and summarized. Cheers, Chris, DL1GKC
Glad it was helpful! 73 Peter
This reminded me of a couple of vintage 1950-60s 'USA novice' CW-only transmitters I have (Eico 720 and a Globe Chief) using 50-watt tube finals and a PI-network tuner output. The instructions for each said to use a coax-fed resonant dipole, but if that were not available, any random wire of 75 feet or so thrown up in a tree would work fine if the rig had a good connection to a ground rod or the house plumbing. And they do indeed work! Those old transmitters seem to be able to load up on just about any wire of reasonable length connected to them. -- John N0BUP
Hi John. Yes I remember those days. No VSWR meters, just neon screwdrivers and old WWII RF current meters - that I burnt out on occasion!! 73 Peter.
thanks for the info very much appreciate your video 73s
Glad you like them!
Thank you for the best video I've seen covering all the key points of setting up and using end-fed non-resonant antennas with 9:1 ununs. I find that the antenna and coax lengths are very important. I now have a 71' sloper, 9:1 unun, 50' of RG8u coax, 3O' counterpoise, and common mode choke attached to my transceiver with a 1' RG8u jumper. Using an inexpensive manual antenna tuner I can get from 1 - 1.5 to 1 SWR on the phone segments of all HF bands 80 - 10. I've made many contacts using 1 to 20 watts SSB. My current project is a 135' sloper that will go from my 25' balcony to the top of a 100' oak tree that's about 150' away. I recommend learning how to calibrate and use an inexpensive NanoVNA to view and adjust antenna, coax and counterpoise lengths for minimum SWR. Thank you again for an extremely helpful and very encouraging video!
Great information. Many thanks for that. 73 Peter
Love your channel. Two years ago I tried the random wire antenna during Field Day using a length the website you reference considered okay. I attached the 9:1 at the base of the slopper and added a radial on the ground for 20m. I attached a line isolator (rf choke) to the coax side of the LDG 9:1 then coax to my mfj tuner and this fed my Ft-991A (it can only match 3:1). Receiving was great. When I hit the PTT the MFJ went nuts and my ft-991A reset. Seems like RF down the line. I have used the isolator since without an issue, so I believe it is working. I have no idea why the set up didn't work. This story aside. My question is this, whenever a counterpoise or radial is used on an EFHW or Random wire antenna, it looks to me like a flavor of an OCFD with a higher impedance. What do you think?
Thanks for this excellent presentation Peter. Your explanation is clear, straight forward and I learned a lot. I'm going to give the LDG unun a try.
Hi Jim. Thanks for that. 73 Peter
I've done a lot of testing with this. A 17 foot counter poise going opposite the antenna lowered and stabilized my swr.
Thanks great channel
Great review and explanation of the workings thanks.
I can attest that the 9:1 antenna is a great performer. I home-brew mine using readily available toroids using the “Earchi” instructions. For field antennas, the toroidal transformer can be fastened directly to a piece of plastic cut into the shape of a winder. I also use a home=brew 1:1 transformer at the rig. My rig is a KX2 with its excellent ATU. I have lots of other experimental antennas, but this is the one I reach for most often for portable activations. I use a 10M telescoping pole and set mine up as a vertical or as a longer inverted vee. The setup time is very quick, and the performance is always satisfactory.
Many thanks. 73 Peter
Very informative presentation. Many Thanks … Peter (M0PGW)
Excellent video; I am surprised that there aren’t more videos on this piece of kit that is cheap, well made, durable, and takes all of 5 minutes to turn any wire more than 30 ft into a very nice, all band antenna (with a tuner of course). I built a 41’ vertical stringing a wire up into a tree above my shack (huge tree). The base of the antenna is 12 ft (4m) where it runs into my second-story shack through only 18 inches of feed line, then another foot of jumper into my rig. I run a 17 ft counter-poise wire through the trees horizontally. The antenna SWR is no worse than an 5:1 on any portion of the hf bands, sometimes dipping as low as 1.8:1 (mine gets there on 80m only). From here it tunes easily into any band - including short-wave broadcasts with a manual tuner. This LDG unun is cheap (about $25 in the US), weatherproof, and well constructed- it feels solid. I built a QRP Guys kit to do the same thing that was more expensive, fragile (it broke swinging around), and not weatherproof; I’m keeping the torrid but trashing the rest of the kit. Don’t go with the QRP guys kit, get this off the shelf unun from LDG. This is a cheap, effective, antenna - just keep the feed line short and use a choke.
Interesting comments. Many thanks. 73 Peter
First RF Choke is paramount, End of Story. I use EARCHI Design FT-240-31 RF Choke with 9:1 T200-2 UnUn and 30 feet of wire which outstanding for local 10 meter and 6 meter Net(s) Also have used same configuration with 53-57 feet of wire with sweet spot on 40 meters and also was able to get 6 meters ; ) I replaced 53 foot antenna with FT-240-31 RF Choke and 49:1 FT-240-43 EFHW and 65 feet of wire which gave small performance increase on 40 meters but lost 6 meters with EFHW : ( I can not overstate the performance of the EARCHI Antenna for me and small front yard city environment ; ) Only thing better for me and my location is ARROW YAGI-UDA Antennas which I only have room for VHF UHF antennas, ARROW ANTENNAS have outperformed everything else I have tried to date. . . Thank You for a great informative channel. . . ; )
Always very informative show!! I've use a 4:1 balun for 11 meters and it works very nicely!! 👍
OK thanks for that. 73 Peter.
Very good man
Thanks
great tutorial peter, there's a lot of recommended random lengths on different site's.... for portable dx i use nothing else, 29.5ft wire vertical, with 2 times 20ft for radials/ counterpoise
this will work ok but best results with this kit is to run the ground/radials/counterpoises away from the unun, 2x10m of mini8 coax with a common ground rf choke, or clip on ferrite at the 10m joint so part of the coax is a counterpoise, these antenna's hate short coax feeds, done right they are a very affective setup
but need a lot of choking and grounding
Update: I built a 41 foot vertical antenna with a single 17 foot counterpoise with this unun. Because my station is on the second floor, and there’s a large tree growing over the house, I was able to pull the 41 foot vertical section into to the tree so that the bottom of it is approximately 12 feet above the ground at my widow level. The single counterpoise is also elevated and simply draped away horizontally through some trees at 90°. I made 4 SSB Parks On The Air contacts on 17 m with this antenna; the longest being from my QTH in the eastern United States to San Francisco California (2500 miles or 4000 km). Good reports of 56. I was running QRP power of only 5 W. The key is my coax feed-line totals only about 2 feet. Very low-loss system.
Many thanks for that.. Sounds a nice serip. 73 Peter
With the wide availibility of 9:1 ununs one or many would think that it was a magic ratio that is absolute and a panecea to match every random length wire in every condition or environment. Many new hams don't realize that 9:1 is just a balllpark ratio to lesson the losses of no transformer at all. Example, I use a homemade 4:1 on my 53 foot inverted L with great results, especially on 20 meters. It is just 12 or 13 turns bifilar wound around a ferrite rod antenna core maybe 5 inches long taken from a scrapped am radio found at a thrift store for about $3.00. As a plus, I use it's companion variable polycap as part of my matchbox tuning. These two parts alone were worth more than the radio.
Point is sometimes a 4:1 or even 5:1, 6:1, 7:1, etc. May be a better "match" at one band over a 9:1.
Ideally, one could construct a transformer with multiple taps for each of these rstios and select the one that gives the best match at the radio, on some cases eliminating the need for a seperate antenna matchbox. In fact on 20 meters and other bands, I don't need a tuner between my feedline and my transceiver. To top it off, I'm using 75 ohm catv line (RG59) to feed it.
By the way great presentation and you covered the subject well. Always enjoy your posts. 73 de KC4QI
Thank you for your video. I am new to SDRs and I have a SDRduo, and purchased a LDG 9:1. I live in a subdivision with a home owner's association and outside antennas are not allowed. I was planning on the following and wanted you opinion. I have now realized after watching your video to get the LDG 1:1 cable choke. Since I currently do not have transmit privileges in the lower bands, the EXACT length is not exactly import yet ( but will be when I upgrade)
I am going to place a long wire antenna in my attic and feed it to the 9:1, install a conterpoise, and feed it via RG8 down in my office/shack to a 1:1 cable choke (as yet to be purchased) then to my SDRduo on one of the 50 ohm antenna ports. (I know that the duo has the high impedance input, but since I have enough RG8 and I am planning on future use. That leads to a few questions that I hope you or the other viewers can help me with:
1) does it truly matter for strictly listening if I install a long wire as long as I can in the attic and even if it has a L shape in order to get a longer wire? I do not think I would be probably listening to much in the the very very very low frequencies just to add
2) would it be better to just place a long wire at straight as possible and terminate it at that time. Once again, when I get more privileges I can and will be trimming it to the desired length
3) for a counterpoise, would it be best to just put a length of wire to the earth lug and lay in in the attic on the trusses OR should I ground it to any of the ground electrical junction boxes in the attic, OR am I causing more potential for interference?
Thank you for all of your help
Fred
Thank you!
You're welcome!
excellent, most informative and practical.
Glad it was helpful! Take care Michel. 73 Peter.
Thanks for the video. Will placing a termination resistor at the end of the random wire make any difference?
The best video on EFLW antennas I've seen so far, and right on the mark when it comes to claims about flat (and low) SWR being something of a fallacy. I have been using these antennas for years and I can attest to that. Very nice job Peter, the clear presentation and explanation of this antenna was so well done.
Wow, thanks!
Thanks, I bought the LDG 9:1 here in the states but haven't used it yet.
Hi Joe, its an interesting unit to play around with. Have fun. 73 Peter
Hello Peter, I have been experimenting with an unterminated "Vee Beam" for 20-6 meters, with my leg lengths currently each at 100 feet. The Vee Beam Apex angle is approx 60 degrees. The wires are up in the air about 35 feet. I have been getting fairly good results and with noticeable gain in the intended direction (NE and SW). My QTH is in NY State. My system is fed with 75 ohm coax, I utilize a common mode "ugly choke using my 75 ohm feedline coax" at the feedpoint of the Vee Beam, and at same location, match my 75 ohm coax with the Vee Beam (essentially now a balanced two end antenna) with my home brew wound 4:1 torroid wound on Type 31 material. My SWR varies across 20-10 meters on the various bands of course, I have tried a 6:1 amd a 9:1 Balun, with mixed results, however I am trying to come up with the ideal lenghts of the wires to created the "highest impedance", thus creating the best overall match.
My question is my choice of 100 feet per leg "good enough" or would 98.5 feet, or even 107 feet make that much of a difference.
Or possibly those lengths don't apply to my un-terminated Vee Beam at all?? I understand am trying to have near mutiples of 1/2 wavelengh for the bands I am intending to work, the goal....
Ideally, I would have a balanced remote antenna tuner at the feed point on the Vee Beam hihi, maybe someday.
I also am not a big Fan of Balanced line at my QTH, lots of Ice Storms here, routing the balanced line into the shack issues etc, etc.
Anyways, my results with the 100 foot lenghts thus far have been good (since March 2023), I run semi QRP at 50 watts, and if the signals are strong I usually can work them. However it is tough to make the contact if the station on other end is running 1000 watts or more hihi and that is understandable, but if they are S9 + I can usually make the contact... I Never get tired with messing with antennas hihi. And also I certainly see a lack of 100 watt or less signals on the higher bands, in solar cycles of the past it was very common/the norm
Hoping for a nice long HF ride on the Solar Peak this cycle, is sure was great conditions in Feb-March this year, will see if this Sept-November will also yield some great conditions for the higher bands, best 73 de Jerry KC2UT
Hi Jerry, I was going to strongly suggest balanced line until I read your reservation. But why not run balanced line back as far as you can, then 4:1 balun followed by short coax run. Even a modest VSWR on a short coax run will have very low loss. Petr.
Great video!! Robert K5TPC
I have had several truly random wire antennas for my SW RXers, typically 10 to 20m long for some 50+ years. At no time have e I used a 9:1 unun. and I have been able to log 1000s of SW B/Cs over the years from here in NZ. A recent article by a very experienced engineer in the US pointed out the impedance of a random wire was typically 3000 to 4500 ohms, not 450. A lab test of the input impedance of a Tecsun PL660 gave a result of 34 ohms on HF, not 50. Hence the use of a 9:1 unun was pointless for receiving. The prime consideration for RXing is the lowest noise floor possible, not impedance matching. People are mixing up max power transfer for a TX, and low noise for RX. I would strongly advise static protection for external RX antennas. (Life member NZRDXL, Life MIEEE)
Hi Ken. The engineer is roughly right. A long wire mis-match on receiver is no bad thing on SW bands. The signal strength attenuation is often beneficial. The nouse floor will also often appear better. That is why most transceivers have attenuators that can be switched. It is the Tx side that must see a good match. 73 Peter.
Great video. I learned a lot in my quest to get a working 80m antenna on a small lot. You mentioned keeping the coax length as short as possible to keep the SWR acceptable. How short is "short" then? 73 de 4F3BZ
So are they still letting the torrid inside the box float or do they actually mount it to the box? Not waterproof either from what I have read.
Thanks for ypur G5RV videos. I thought he was RSS ww2 and his army RCofS insignia seems to prove this. I've visited the Forfar RSS site.. I lived along the road! I started a bit like Louis. By 19 I was in the military having studied elwctronics, did some crazy mods to radios and they snapped me up. Military listening, training with Q, my bosses were trianed at Bletchley. It's been a pleasure to get my foundation. I termediate to come and then Full. I do CW to decent speeds.. I shpuld be like a mix of class A and full one day. Blended! I'd hope to give back to a hobby (a calling really for many of us) and train and inspire the not so secret hams as I was. 73 M7XNR
Thank you, very informative. May I ask a question, can we use this type of setup for NVIS antenna?
Yes, you can. 73 Peter
Hi Peter, great video and much appreciated, however I just have a quick counterpoise question.
I will be using a roughly 44ft wire with a 9:1, a line isolator located at the radio end and it will have about 15m of coax.
With the line isolation at the radio side I understand that the coax will be acting as a counterpoise with that length of wire, so will I need or really benefit from an additional counterpoise attached at the unun?
Thanks, William.
You don't mention whether vertical or horizontal, but generally there is little to be gained. However, a counterpoiise also tends to keep RF out of the shack so it really is your choice.
As usual an interesting, informative and above all, down to earth episode. Thank you.
Btw do not see a link to the web page you mentioned.
Many thanks. 73 Peter
Really appreciate that Peter. I am frustrated with end feds. So some good explanations there. Im wondering on the necessity of a counterpoise if used vertically on a fishing pole. Any thoughts? VA3SII G7HCD
Verticals certainly need radials. The EF wire is a bit different. A counterpoise is normally above ground and as such becomes part of the radiaring antenna. This means it has quite an effect on resonance. I would recommend it but be pre pared for a resonance shift. 73 Peter
Hi, having watched the video I'm thinking about a random wire, what would be your thoughts on a random length of wire run along top of a fence, my thought is with having a small garden, to run a wire down one side fence, along bottom fence and back up other side fence, in effect a "flat n" shape, would it work would you expect it to be efficient or inefficient
Regards
Eddie
i was going to try this with 53ft of wire and about 1m of coax feeder to the unun.
will i need a counterpoise?
my garden is just about 53ft and i can not use a vertical.
7s
M6CTP
I find your videos so interesting, you are such a good teacher. One question, when you say a slightly high SWR doesn't matter as the length of coax feed is very short what do you mean ? Why might a high SWR on a short length of coax not be a problem but on a long bit of coax it might ? I thought SWR referred to the amount to energy returning to the transmitter which wouldn't be good. Many thanks again.
We are talking about HF I think? A VSWR of 4 or 5:1 on a length of coax about 3 or 4m long is not a problem as regards loss. 2 or even 3:1 on 25ft is not likely to provide any noticeable loss. Even longer at lower frequencies. Almost any length ar 2:1 is workable with not noticeable loss. Hope that helps. 73 Peter.
@@watersstanton Thanks Peter, yes HF. So that wouldn't be a problem for the transmitter with an ATU, I'm guessing without an ATU its likely to upset the transmitter ? Many thanks for your reply.
Hi Peter, thank you for a very insightfull video. I'll be adding a counterpoise to my 9:1 unun soon and am happy I now have some sort of idea how long this counterpoise has to be. One more question though: do I put the line isolator after the antenna tuner (LDG Z-100) or in between the antenna tuner and the transmitter (Icom 7300)? Thank you! 73's Alexander PE0ALX
The line isolator goes at the end of the antenna feeder, so that means on the antenna side of the ATU.
@@watersstanton thank you very much for your answer.
The only thing that would concern me about living with 4:1 SWR is the amount of reverse power dissipated in the finals. Anything over 2:1 and I would be running reduced power and 4:1 and above, I would be running 6dB down or less.
My good sir, top of the day to you. Excellent explanation of the 9:1... I would like to add however that when you speak of the ATU, you assume everyone has an ATU built into their transceiver which is not the case. Why not talk about external antenna tuners as well?
As a 'length of wire' user for the last year I think its only drawback is that it picks up more noise & interference than a tuned antenna (which figures if you think about it). This in turn makes reception a bit less sensitive. The counterpoise is both essential and interesting -- my 'counterpoise' ("the other length of wire") ended up near a formal ground point so I naturally assumed that it would benefit from being connected to ground (through capacitor etc. to prevent ground loops). This killed the antenna's performance completely. I haven't figured that one out yet!
This antenna is tuned and I NEVER use a counterpoise with any EFHW. BUT I always use a line isolator at the Tx end. 73 Peter
Hi Peter, I have a EFLW, 53 ft. I have an IC 7300. I am using a 9:1 unun about 15 feet off of the ground with 50 ft. of RG18 just laying on the ground. I also use a autotuner before my SWR bridge. All the bands tune from 1.2 to 2.0 except for 40 meters. It runs around 3.5:1. Can't understand it. Do you think a counterpoise might help? Is this the nature of the EFLW? I get great reports on 40m. however. It is a puzzle. Thanks for your videos. Always well done.
Hi Frank. i would suggest you do nothing. If you get an improvement with a counterpoise, it may well make some other bands, worse. BUT in ham radio everything is worth trying! 73 Peter
Could you tell us the configuration of your random wire please. Straight? Slope? Inverted L? And how high was each end above ground level? Thanks for an informative video. Cheers and 73.
The antenna was horizontal. height was about 20 feet. 73 Peter
Peter, with the configuration you describe with the unun in a second story ham shack, how and where would you install a lightning arrestor? Many thanks
Between transceiver socket and coax feeder.
There are lengths of wire that are to be avoided: where the wire is a half wave on the band that one is intending to operate on: I guess in that case one might get the 49:1 unun out! Lists of ideal lengths that avoid this scenario for all bands are available online.
Yes you are correct.
Was your counterpoise the same length as your radiating element. You said 3 meters then you said 40 feet. thx
Yes just 3m long.
I recently tried some 9:1 baluns built from commercial kits one had that lovely low swr on all bands, but it was incredibly lossy (greater than 50dB on my VNA).
Yes the 9:1 can be a questionable item, but that loss suggests a construction problem.
Why do some end fed wires ie for 40/20m with coil like your previous video not require an unun but some do?
The small coil is not essential but helps to correct the VSWR drift as you go up in frequency. 73 Peter
I found the wire lengths provided by the document mentioned do not actually work well. I tried 53' and it never tuned well and nobody could hear me. I changed the length to 41' with 25' of coax and it tunes up everywhere and I am making contacts at 15w.
Interesting, thanks. Just a small point: you will always need to use an AMU, as even when the wire impedance hits 450 ohms at a particular frequency, it will have a reactive and a resistive component. The transmitter needs a 50 ohm resistive load for good matching, otherwise the SWR will be poor.
Hi Mike, thanks for that. I did actually achieve 1.3:1 on 20m but at the cost of high VSWR on most other bands. 73 Peter
@@watersstanton 73 and good health Peter de Mike ok8msw ex g4ome
This is the hole in my knowledge filled - I knew I needed to put my dips in the right place for 450 ohms, but wasn’t sure why I then needed the tuner as well. I assume it has something to do with it not being a half wave on that wanted frequency, perhaps?
In my humble opinion, the better solution is to use a wire that you resonate on the lowest F band of interest and use it with a multi-tap UNUN for a multi-band, no tuner needed solution :)
At about time 15:25 you mention that the line insulator must be next to the rig. But I've seen many articles that put the current choke at the antenna end. Usually, at the closest - to the antenna - place in the coax. Usually, it's done by creating a coil of about 8 turns on a PVC cylinder about 6 inches in diameter - something like that. Instead of coax turns, one could use "beads" instead - but again, they go close to the antenna.
So I'm puzzled about the line insulator going next to the rig. If you had an external Antenna Tuner, wouldn't it go before the tuner? Where is my mistake in thinking it should go at the beginning (non-rig end) of the coax? I do understand that I am assuming that 1:1 is the same as a current choke and that could be my error.
Thank you for putting this video (and the others) together.
Firstly you don’t need an external tuner but if you do, then isolator does go between tuner and antenna. I don’t recommend an isolator at transformer end because there is no benefit and the coax is free to act as a counterpoise, although that aspe t is ooen to opinion. 73 Peter
@@watersstanton Peter, thanks to your video, I now understand more about the difference between a random wire end-fed vs a half-wave end-fed. When you say I don't need an external tuner, are you assuming the rig has a built-in ATU. Because I'm pretty sure everything I've read about a random wire end-fed is it needs a 9:1 UNUN and a tuner - either in the rig or external.
The other "contrary" opinion I'm struggling with is some say to run the counterpoise parallel with the antenna and others say run it at 90 degrees. Of course, we end up running it whatever way we can given the geometry of our backyard.
Maybe it's the Half-Wave that wants a choke just after the 49:1 UNUN?
Hi Peter great video, I have recently purchased a 9:1 unun multi band with 41meters of wire on it I have a big garden so space is a premium plus two big trees at the end of the garden to wrap the wire around. Going to purchase one of them ldg isolators. Question so the end of the wire which is ended at a bone does that need to be close to the ground or for better purposes as high as I can get it. Thanks
Keep it up in the air. 73 Peter
@@watersstanton thanks
The " choke " clip on ferrites, acceptable? If so how many? Intended to use external LDG RT100 in roof space with a couple of feet of RG8x before UNUN
I have always found ferrite rings are better.
Thank you what do you do with the ground so239 unun? to ground rod for lighting protection? im up on a mountain in verginia
You can take the ground tag down to an earth rod, but if it is up in the air, there is no point. 73 Peter.
I made one with 37.5m of wire. To my surprise it was low vswr on 7,10 and 14MHz. I put it on an analyser and it was actually OK at the top of 21 and 29. I never managed to make it work on 80m. I also tried a 5.5m counterpoise. This made it identical to a W3EDP. I found this helped on 28 but threw all the other bands out. You do need the line isolator. Without it it's a very noisy antenna. Very useful for a temporary or listening antenna. A half wave is a lot easier to set up.
Thanks Gordon. Similar to my findings. 73 Peter
Would measuring this unun with high inductivity wirewound 450ohm resistors give out a bad swr reading? I built one of these, and although I think the core is of satisfactory quality ( T130-2), I get around 2.7 swr with a resistor. When try to use it with a wire the dips newer go below that number either.
you should always us a non inductive resistor. If you do you should see a perfect match. 73 Peter
RF resistors work well for measuring baluns and ununs. You could get a bunch of 50 ohm ones and connect them in series to achieve resistance you need. They also make great dummy loads.
j'ai d'excellent résultats (concernant le SWR) avec 15,80m de fil d'antenne et un coax de 25m en guise de contreproids et une mise à la terre du Transceiver (pour améliorer la partie 3.5Mhz).
J'ai au maximum 2.4 de SWR de 80 à 10m en Slopper avec le UnUn au sol, et un RF Choke juste avant le transceiver.
de 20m à 10m je préfère utiliser une 1/4 wave GP que je trouve plus efficace.
Le 9:1 est meilleur en bas ! ( de 80 à 30m)
Ok . . . Im confused. When would you use a 49:1 v a 9:1 unun? Does it depend on your tuner and/or the amount of bands you are trying to access on one antenna?
I think I answered my own question. Thx.
Like the show but do not expect a LDG balun to hold up to 100w with anything more then a 2:1 swr. I was using a 4:1 balun to bring my doublet into a at200proII and my god only 5 min into to the transmit ssb and the balun case was melting. then the tuner started tuning mid transmit. Took it off put my old faithful Dentron manual tuner online and it was fine. Tried using at200 with coax and had similar issues. It be tuned, then I try to tx and it start cycling through relays. So I threw 3 boxes and the tuner into the circular bin for good. Real tuners have inductors fixed and /or adjustable ☺️
OK Kevin. Mine is holding up so far. Will do a temperature check. 73 Petrr.m
@@watersstanton yea I was surprised as my hw diepole was 160m and up at 100’ so I figured balanced feed was best for losses and the feed was 100’. When trying to tune 80m it just couldn’t with it being a huge vswr with the feed being a 1/4 wave long. So I just stayed on 160 where ant was happy.
@@watersstanton Please let us know about the temperature check. You can even remove the lid to get access to the balun and windings. If there is any balun heating, does it depend on the frequency band in use and the SWR?
I have a LDG Z11Pro autotuner and it sometimes starts tuning while I'm in QSO and it drove me up the wall. One time I was listening on HF and on a 2meter net and when I keyed my handheld, not connected to the tuner, the tuner started tuning! What I recommend doing is use the tuner in semiautomatic mode, i.e. it will only tune when I push the Tune button on the tuner. As for the balun, I use a balun from MFJ that can be switched between 1:1 and 4:1. It was able to tune a 60 foot doublet fed with 300ohm twinlead on 80-10meters. I don't have that antenna at the moment, but plan to build something similar soon.
Which would be more efficient (Less RF loss), A 9:1 transformer or an Icom AH-4 ATU on a random wire?
Is a random wire better (RX Noise? or?) as a vertical or horizontal antenna?
Icome is better. Moise is often related to location rather than antenna type.
The higher SWR may be of no significant consequence to signal strength, but be aware that most modern radios will start folding back on power output as the SWR rises above 2:1.
73 de Arnie W8DU
Which is why I emphasised the need for some kind of matching unit, in or outside the radio. 73 Peter.
👍👍👍
Thanks.
OK, now I am a little confused. I have a 117 foot straight wire antenna and the ferrite transformer box. I do not understand the counterpoise if it is just a long piece of wire or is it actually supposed to be grounded. I have the so called counter poise and my transceiver chasis to a 12 foot grounding rod in the ground. Is this ok? N6ZKI
Generally, a counterpoise can be regarded as part of the antenna. As such it should be connected to the shield side of the coax at the UnUn. I personally add a ferrite choke near where the coax leaves the box back to the radio. The counterpoise would then be floating and become part of the antenna.