|
random wire antenna
Hi all,
I installed a random wire antenna of about 80 ft. Inside the shack I would like to run coax to the outside and connect it to the wire. The question is now what kind of matching transformer (UNUN) do I need to get a good match. Thanks for any answers. Fred wb6iiq |
On 19 Nov 2004 18:46:59 -0800, (Fred) wrote:
The question is now what kind of matching transformer (UNUN) do I need to get a good match. Hi Fred, You are shy of a lot of information necessary to respond to your particular needs. So to answer what is left: 1:1 Current BalUn Tuner 73's Richard Clark, KB7QHC |
"Richard Clark" wrote (Fred) wrote: The question is now what kind of matching transformer (UNUN) do I need to get a good match. Hi Fred, You are shy of a lot of information necessary to respond to your particular needs. So to answer what is left: 1:1 Current BalUn Tuner Adding to Richard's comments, many antenna tuners have a built-in 4:1 Balun in them, some only make this available on certain settings. A 4:1 Balun at the feedpoint of a 70-80' random wire will typically match very easily (on a tuner of course) from 160 meters through 40 meters or above. You can additionally, mount the Balun on the top 12" of an 8' ground rod, and ground one of the two Balun outputs to the ground rod, connecting the other to the wire as a feed. This is one of my very effective antennas, and quiet even in a highly populated area. Industrial Communication Engineers (ICE) also makes a nice matching device with adjustable impedance setpoints where their Balun is automatically grounded and provides lightning protection as well. That device is however for receive-only. Jack Painter Virginia Beach VA |
Hello:
Transceiver---- coax 50 ohms ------ balum 9:1 ------- randon wire of 42 meters long It is an efective antenna to 3,5 to 50 Mhz. Transceiver----- Match --------- coax 50 ohms ---------- balum 9:1 ------- random wire. Bye. Jesus. "Fred" escribió en el mensaje om... Hi all, I installed a random wire antenna of about 80 ft. Inside the shack I would like to run coax to the outside and connect it to the wire. The question is now what kind of matching transformer (UNUN) do I need to get a good match. Thanks for any answers. Fred wb6iiq |
I accidentally found your discussion. Having nothing else better to do I thought I would make the following remarks - The 9:1 balun on a 'long wire', on the average, has no effect on what you call the antenna 'effectiveness'. On receive, you may find the signal strength marginally better at some random frequencies and marginally worse at other random frequencies. 4:1 baluns have a similar negligible effect at different sets of random frequencies with a very slightly smaller overall loss over the whole wide band from MF to HF. You may just as well omit a balun altogether. Omission of a balun means zero balun loss. But loss in a balun is negligible anyway. It just means there is nothing to be gained by fitting one. Baluns can be useful in particular frequency bands. But if you are interested in particular bands then a very simple tuned antenna, a coil or capacitor, or changing antenna length, is much to be preferred. Baluns in a receiving application are beneficial only to the bank-balances of balun manufacturers and salesmen. In other words, don't waste you hard-earned money! (PS: The supposed 600-ohm Zo of a random length of wire has very little to do with it. Concentrate on the exact particular antenna length. Please send me the money you save.) And forgive me for the interruption. ---- Reg , G4FGQ |
The supposed 600-ohm Zo of a random length of wire has very little to
do with it. =============================== Depending on length, height and wire diameter, Zo can vary between 450 and 650 ohms or thereabouts. What's yours? Then what balun ratio would the guru's and old wives recommend? And to confuse even further, receivers can have an input impedance anywhere between 50 and 1000 ohms. Some tuned receivers have an indeterminate input impedance. Who needs a balun? ---- Reg , G4FGQ |
On Sat, 20 Nov 2004 21:28:54 +0000 (UTC), "Reg Edwards"
wrote: The supposed 600-ohm Zo of a random length of wire has very little to do with it. =============================== Depending on length, height and wire diameter, Zo can vary between 450 and 650 ohms or thereabouts. What's yours? Then what balun ratio would the guru's and old wives recommend? And to confuse even further, receivers can have an input impedance anywhere between 50 and 1000 ohms. Some tuned receivers have an indeterminate input impedance. Who needs a balun? ---- Reg , G4FGQ Well Reg need and want are two different things. Perhaps my inverted L didn't 'need' a balun, however after installing an ICE-182A DC-Isolated matching transformer (balun if you will) I had a noticeable reduction in noise. The difference is real and as a result I have a better S/N ratio that makes listening less fatiguing. Now here's the $64,000 question ........"Was the difference due to impedance matching, the DC isolation or did a previously un-noticed loose ground get fixed when I put the ICE unit in-line?" Howard |
"Howard" wrote "Reg Edwards" wrote: The supposed 600-ohm Zo of a random length of wire has very little to do with it. =============================== Depending on length, height and wire diameter, Zo can vary between 450 and 650 ohms or thereabouts. What's yours? Then what balun ratio would the guru's and old wives recommend? And to confuse even further, receivers can have an input impedance anywhere between 50 and 1000 ohms. Some tuned receivers have an indeterminate input impedance. Who needs a balun? ---- Reg , G4FGQ Well Reg need and want are two different things. Perhaps my inverted L didn't 'need' a balun, however after installing an ICE-182A DC-Isolated matching transformer (balun if you will) I had a noticeable reduction in noise. The difference is real and as a result I have a better S/N ratio that makes listening less fatiguing. Now here's the $64,000 question ........"Was the difference due to impedance matching, the DC isolation or did a previously un-noticed loose ground get fixed when I put the ICE unit in-line?" Howard You know Howard, it's mostly amateur radio operators who have read too much and worked too little that make statements like "a balun for receiving is just for the balun makers benefit". These hams have little idea how hobbyists who have special interest in DX, especially utility, and have tried and tested numerous receiver antenna systems over the years. As I said earlier I too use ICE equipment on one receive-only antenna. I could care less what a stuffed-shirt thinks that does for my receive ability, as I used it first as a hobbyist and then professionally. It certainly does improves my digital and analog signal reception. I have that Ice box impedance set to favor the lower bands on the wire and it at times outperforms a matched dipole in reception. The compromise is that I lose usefulness of that wire much above 6 mhz,which is ok as it does it required job superfluously. Now the 4:1 current-type balun use on another wire-set antenna provides quiet listening as well as excellent transmit abilities from 2182 Khz through 11000 Khz. And of course I use a 1:1 current-balun on a long dipole. Would I "have" to? Of course not. Does it improve the antennas abilities in listening as well as transmit? You bet it does. Do what works for you and God help anyone who argues with that. Jack Painter Virginia Beach VA |
Decoupling reduces the noise (rf current) traveling on the shield of the coax, both to, and from your shack, which would otherwise get pretty much direct coupled to your antenna. |
Hello,
you should try the Magnetic Line Balun (MLB). It is a ferrite (not powderiron) core with a 9to1 ratio. Take three wires, twist them and turn them around a ferritering. Set them in series. The lower winding to the (t)rx het high to the wire. It simply works fine on the receiver and with a trx with a tuner. "Dave VanHorn" schreef in bericht ... Decoupling reduces the noise (rf current) traveling on the shield of the coax, both to, and from your shack, which would otherwise get pretty much direct coupled to your antenna. |
Dave,
this is exactly what I'm after. The RF in the shack it is causing all kinds of problems. My TS50 is turning itself off, sprinklers turning on etc. Thanks Fred wb6iiq |
|
This is, really, a very common topic here. The praises heaped upon
expensive "BalUns" comes at the cost for simple ferrite plus rather stiff prices added for advertising and the illusion of worth. Simply take common garden variety ferrite cores and stack them up on a 12" length of RG-58. Very simple: one gozinta and one comesoutta. This alone will quiet noisy receivers, remove RF potentials on the case, cure rigs of instability; and make sprinklers and touch lamps settle down. Consult the archives for 1:1 BalUns, ferrite chokes, et. al. to research the nuances of which ferrite you should use (or simply build the conventional coiled coax choke). 73's Richard Clark, KB7QHC ============================= - - - - and if your antenna or feedline is balanced, just get a ferrite ring, about 2" in diameter, and wind on it a dozen or so turns of 18 or 20 gauge, twin, stranded, flexible, Radio-Shack speaker cable. Transmission loss is sensibly zero. Just keep length of cable on the ring less than 1/10 th of free-space wavelength at the highest frequency of interest to avoid sprurious responses. It's about time great, heavy, hanks of coax were removed from the handbooks. Ferrites have been around for at least 50 years. But I suppose authors must have SOMETHING to write about. ;o) --- Reg. |
Well Jack, I use one too. Yes, it makes a difference. No, you will not
likely get anyone on a ham group to agree with you. It seems that the SWLs are not the only ones to do this. Drake builds them into their recievers. Why would a manufacturer include a non functional part? "Jack Painter" wrote in message news:4XPnd.8198$D26.7997@lakeread03... You know Howard, it's mostly amateur radio operators who have read too much and worked too little that make statements like "a balun for receiving is just for the balun makers benefit". These hams have little idea how hobbyists who have special interest in DX, especially utility, and have tried and tested numerous receiver antenna systems over the years. As I said earlier I too use ICE equipment on one receive-only antenna. I could care less what a stuffed-shirt thinks that does for my receive ability, as I used it first as a hobbyist and then professionally. It certainly does improves my digital and analog signal reception. I have that Ice box impedance set to favor the lower bands on the wire and it at times outperforms a matched dipole in reception. The compromise is that I lose usefulness of that wire much above 6 mhz,which is ok as it does it required job superfluously. Now the 4:1 current-type balun use on another wire-set antenna provides quiet listening as well as excellent transmit abilities from 2182 Khz through 11000 Khz. And of course I use a 1:1 current-balun on a long dipole. Would I "have" to? Of course not. Does it improve the antennas abilities in listening as well as transmit? You bet it does. Do what works for you and God help anyone who argues with that. Jack Painter Virginia Beach VA |
A balun isn't primarily for this job, but it works here. A balanced antenna plus a balun would be best. There are those who say they can't tell any improvement with this, but that says to me that they have other and larger problems. |
"CW" wrote
Well Jack, I use one too. Yes, it makes a difference. No, you will not likely get anyone on a ham group to agree with you. It seems that the SWLs are not the only ones to do this. Drake builds them into their recievers. Why would a manufacturer include a non functional part? Hi C, I wish there was easy consensus on the subject, with comprehendible (to me) science behind why Baluns help. But in the end there is a general consensus of the unwashed, we non-phd's of radio engineering who desire the electrical isolation, control of feedline radiation when swr is a bit high, and agreed upon improvement in signal to noise ratio, which some argue theoretically cannot be accurate. For our distant worked stations or mobiles, we seem to have reason enough. I stopped trying to explain to the very friendly but rigid thinking folks at Radio Works (where my Baluns come from) - that I enjoy the configuration of a random wire end-fed with one-half the balun shorted to ground. "That cannot work" they tell me, yet not only did a real Doctor of Electrical Engineering release this noise-limiting design in an old issue of "Proceedings", but I have worked aircraft 3,000 miles away with reports of "loud and clear" (exactly how they sounded to me). It's one of the best antennas that doesn't work I ever had! At least there have been friendly and interesting comments offered by all on this topic, and something to learn as the gurus weigh in ;-) Jack -end - "Jack Painter" wrote in message news:4XPnd.8198$D26.7997@lakeread03... You know Howard, it's mostly amateur radio operators who have read too much and worked too little that make statements like "a balun for receiving is just for the balun makers benefit". These hams have little idea how hobbyists who have special interest in DX, especially utility, and have tried and tested numerous receiver antenna systems over the years. As I said earlier I too use ICE equipment on one receive-only antenna. I could care less what a stuffed-shirt thinks that does for my receive ability, as I used it first as a hobbyist and then professionally. It certainly does improves my digital and analog signal reception. I have that Ice box impedance set to favor the lower bands on the wire and it at times outperforms a matched dipole in reception. The compromise is that I lose usefulness of that wire much above 6 mhz,which is ok as it does it required job superfluously. Now the 4:1 current-type balun use on another wire-set antenna provides quiet listening as well as excellent transmit abilities from 2182 Khz through 11000 Khz. And of course I use a 1:1 current-balun on a long dipole. Would I "have" to? Of course not. Does it improve the antennas abilities in listening as well as transmit? You bet it does. Do what works for you and God help anyone who argues with that. Jack Painter Virginia Beach VA |
Let me try to summarise.
A simple thing like a balun does only two simultaneous things. It changes the impedance presented to the receiver (or transmitter). And, because it disconnects the usually slightly radiating feedline from the antenna, it changes to some uncertain extent the antenna's directional properties both locally and at a distance. On receive, the change in impedance matters very little. It doesn't matter very much whether the impedances involved are 600 or 300 or 50 ohms. They are quite arbitrarily decided by the mechanical construction of the transformer and are arithmetically derived by (often wildly incorrect) assumptions of values for line and receiver impedances. The change in the antenna's directional properties sometimes, but not always matters. It depends on the local environment and can affect such things as signal to noise and signal to interference ratios. But you never know until you've tried it. The very general moral is - if there's an improvement in performance in any respect due to fitting a balun then keep it. If there's no improvement then you could leave it where it is or try to sell it back to the manufacturer. It will seldom degrade performance. On rare occasions, fitting a balun can make matters worse. But once again you'll never know until you've tried it. And the "made worse" circumstances are never reported in magazines. This causes bias in the statistics. It can hardly be called "engineering". But there's nothing else one can do in the presence of inevitable large uncertainties in the local environment. It's this piquancy which adds to the pleasure of both amateur and professional radio. Professionals who have to earn a living play safe by predicting radio paths to be typically within plus or minus 15 or 20 dB. Amateurs have the time to spare to quibble about minute fractions of S-units. And balun and antenna salesmen have no alternative but to hover around and attempt to make a living out of the suckers. Everyone has a right to make a living. ---- Reg, G4FGQ |
Thank you all for your help. I used Richards approach and Bingo all my
problems went away. 73 Fred wb6iiq |
| All times are GMT +1. The time now is 07:57 AM. |
Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
RadioBanter.com