Re: Topband: 2 wire Beverage question
Carl, It sounds like you are asking if transposing the two Beverage antenna wires at either end will make a difference. It will not. For a single, bi-directional Beverage or BOG, phasing does not matter. Are you going to phase two parallel BOGs together? 73, Mike www.w0btu.com On Thu, Oct 3, 2013 at 8:13 PM, Carl k...@jeremy.mv.com wrote: I want to install another 2 wire BOG and experiment with different lengths and at the same time use up some extra lengths of MIL telephone wire. When wiring the sections in series do I have to maintain phase or isnt it relevant? IOW, does the wire leaving one side of the feedline end transformer have to be connected to the same end at the reflection transformer? Carl KM1H _ Topband Reflector
Re: Topband: 2 wire beverage question
This is very convenient for me. Can I just put up two of these side by side a foot apart and have a differential impedance of around 600 ohms? A two-wire Beverage operates in two modes, common mode (antenna) and differential (transmission line) mode. The common mode works correctly and non-critically no matter what we do, and is pretty much independent of what type of wire is used or how the wire is used. The differential mode is the more critical issue, because differential mode and the transformer system at the far end supplies termination impedance to the far end. While almost anything will work to the extent of making some happy, the transmission line impedance of some twisted pairs can change by 50% or more when wet compared to dry. Also, if the line adds significant signal transmission loss in reverse mode, flaws in line balance become more apparent. This is because differential loss increases while antenna mode losses do not. This doesn't mean it quits working, it just won't have the front-to-rear ratio of a good installation. I looked at this all in the late 1970's and early 1980's, and sometime after that I wrote an article detailing a system using ladder line (which was the best wire) in an obscure northern Ohio newsletter called the Amp Letter. I used real 450 ohm air line in that antenna. I've never looked at the care of wide-spaced wires close to earth. The closest I've look at was a 1500 foot long air insulated transmission line with just under 3 wire spacing here at my QTH. With under 3 spacing and 8 to 10 feet height, loss and impedance was stable under all weather conditions. Without twists in that line, it had noticeable signal leakage on mid HF and higher. With twists every 20 feet, it was only a problem up near ten meters. On lower bands, it was almost like coax for ingress. I'm not sure what, if any, problems would appear in other line configurations. I suppose results would depend on how fussy you are and what is around the antenna. What would be even better would be a very light weight twisted pair, but is such as thing available, now that phone lines are ruled out? I guess 300 ohm twin lead is ruled out because of the rain degradation issue. Probably too much wind load too. The twisted pair in CAT5 cable seems like a good RF candidate if an easy way could be found to liberate one pair from 400 feet of cable. Still might be affected by rain. Antenna results are a mixture of many things. While they work the way they work, we often invent or exaggerate some positive or negative aspect. If we want stable coax-like performance, the balanced line mode has to act like an acceptable transmission line in all weather. It stands to reason the very worse lines are twisted pair lines with fibrous coverings. The water easily fills the area in the line between and around conductors, and it stays there. Wider spaced lines, especially those that push the water away from conductors and between conductors, are much better. Open wire lines (real ones) are better yet, because there is not very much for water to collect on. I think 300 ohm or 450 ohm transmitting twinlead (which is never 450 ohms, and actually has more loss than the ARRL claims) is a good compromise, but almost any type of line can be made to work. It is all in the degree of what we look for. I wouldn't be afraid to use twinlead lines, but I'd be reluctant to use 50 year old audio paired cables or unshielded twisted pair. I'm getting old and lazy but just not that cheap yet. :-) 73 Tom ___ Topband reflector - topband@contesting.com
Re: Topband: 2 wire beverage question
Rick, Why don't you just mount them on permanent posts (or trees) 10' high? That's what I and many others do. That ought to let you mow around them without taking them down. My support posts are 100' apart. Two 10' high 14 AWG wires spaced 12 would have an impedance of 710 ohms. The impedance of both wires to ground would be 316 ohms. Consider that when you are making your 3 matching transformers. 73, Mike www.w0btu.com On Wed, Nov 28, 2012 at 7:05 PM, Rick Karlquist rich...@karlquist.comwrote: I think I might like to try some reversible beverages, but I would like them to be made so I can easily roll up the wire on a spool to do mowing, etc. I currently use 19 gauge aluminum electric fence wire on 3 foot high plastic electric fence insulators with a spike on the bottom. I space the supports every 50 feet. I step on them to put the spike into the ground. This is very convenient for me. Can I just put up two of these side by side a foot apart and have a differential impedance of around 600 ohms? ___ Topband reflector - topband@contesting.com
Re: Topband: 2 wire beverage question
Correction: In my last message, I calculated the impedance at 60 high. These are the impedances at 120 high: Two 10' high 14 AWG wires spaced 12 would have an impedance of 710 ohms. The impedance of both wires to ground would be 357 ohms. 73, Mike www.w0btu.com ___ Topband reflector - topband@contesting.com
Re: Topband: 2 wire beverage question
On 11/29/2012 8:14 AM, Mike Waters wrote: Rick, Why don't you just mount them on permanent posts (or trees) 10' high? That's what I and many others do. That ought to let you mow around them without taking them down. My support posts are 100' apart. Thanks for the suggestions, but... First, I have found that Beverages work better at 1 to 3 feet off the ground than at 10 feet. Second, while mowing around the posts is better than having to go around the whole wire, it is still too much of a hassle. I am using a brushhog, not a zero turn radius mower. After mowing, I would have to use the weed whacker around the posts. Third, I am planning to disc the area next year, so I would have to take out the posts. The beverages are basically in a treeless area. 73 Rick N6RK ___ Topband reflector - topband@contesting.com
Re: Topband: 2 wire beverage question
Sounds like a problem many would love to have! When you say they work best at 1-3' how exactly do you mean and what are the antenna details? Getting more info on what others use is always good. Carl KM1H - Original Message - From: Richard (Rick) Karlquist rich...@karlquist.com To: Mike Waters mikew...@gmail.com Cc: topband topband@contesting.com Sent: Thursday, November 29, 2012 6:06 PM Subject: Re: Topband: 2 wire beverage question On 11/29/2012 8:14 AM, Mike Waters wrote: Rick, Why don't you just mount them on permanent posts (or trees) 10' high? That's what I and many others do. That ought to let you mow around them without taking them down. My support posts are 100' apart. Thanks for the suggestions, but... First, I have found that Beverages work better at 1 to 3 feet off the ground than at 10 feet. Second, while mowing around the posts is better than having to go around the whole wire, it is still too much of a hassle. I am using a brushhog, not a zero turn radius mower. After mowing, I would have to use the weed whacker around the posts. Third, I am planning to disc the area next year, so I would have to take out the posts. The beverages are basically in a treeless area. 73 Rick N6RK ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5426 - Release Date: 11/29/12 ___ Topband reflector - topband@contesting.com
Re: Topband: 2 wire beverage question
ON4UN states in his book that the wires for a 2 wire reversible beverage must be installed side by side, but also may be placed one above the other with satisfactory results. Did someone try this? How satisfactory is satisfactory? There is no difference at all. If the feed system is right, and the line is properly constructed, it would all work virtually the same. It does not matter if one wire is above the other, or if they are side-by-side. Absolutely the best construction method would be a twisted or transposed line, twisted or transposed at fractions of a wavelength, but even using the best twisted or transposed installation it would be difficult to tell from an untwisted line if the conductor was very close spaced (a few inches or less). What does make a difference is the wire used, and how the line behaves as a transmission line. I would not use telephone, insulated wire twisted pair, or field phone wire, because they are very poor transmission lines that are lossy and heavily affected by water. The wire layout of good line, however, is meaningless (except for transposing or twisting which can help maintain balance). ___ Topband reflector - topband@contesting.com
Re: Topband: 2 wire beverage question
** Ive noticed no difference in any weather using field phone wire which happens to be in wide use by many very competitive contesters and lowband DXers. With 5 2 wire reversibles here and 750' of 1/2 feedline there is no need for a preamp. I'm talking about: 1.) impedance change 2.) reactance caused by loss Since the impedance presented at the far end of the antenna (in termination mode) varies with weather and is reactive (with high and variable dielectric losses), termination can be unreliable. Maybe that's why you think I have a remote receiver :-) ? The galvanized thin fence wire you often champion is also lossy. That's an apples and oranges comparison. First, I don't champion galvanized wire. That aside, there is nothing wrong with using it in normal Beverages of reasonable length. It is not terminating the system for F/B, and the termination impedance and loss does not vary with weather. ___ Topband reflector - topband@contesting.com
Re: Topband: 2 wire beverage question
There is no practical difference, unless the wires happen to be widely spaced. (But Tom knew that. :-) Some people want to build their Beverages with the wires a foot apart. In that case, one wire over the other would not be ideal. 73, Mike www.w0btu.com On Wed, Nov 28, 2012 at 9:49 AM, Tom W8JI w...@w8ji.com wrote: ON4UN states in his book that the wires for a 2 wire reversible beverage must be installed side by side, but also may be placed one above the other with satisfactory results. Did someone try this? How satisfactory is satisfactory? There is no difference at all. If the feed system is right, and the line is properly constructed, it would all work virtually the same. It does not matter if one wire is above the other, or if they are side-by-side. ___ Topband reflector - topband@contesting.com
Re: Topband: 2 wire beverage question
I think I might like to try some reversible beverages, but I would like them to be made so I can easily roll up the wire on a spool to do mowing, etc. I currently use 19 gauge aluminum electric fence wire on 3 foot high plastic electric fence insulators with a spike on the bottom. I space the supports every 50 feet. I step on them to put the spike into the ground. This is very convenient for me. Can I just put up two of these side by side a foot apart and have a differential impedance of around 600 ohms? It would be twice as much work, but the amount of work is very little as it is now, and eliminating the backhaul coax from the far end would save a ton of work. What would be even better would be a very light weight twisted pair, but is such as thing available, now that phone lines are ruled out? I guess 300 ohm twin lead is ruled out because of the rain degradation issue. Probably too much wind load too. The twisted pair in CAT5 cable seems like a good RF candidate if an easy way could be found to liberate one pair from 400 feet of cable. Still might be affected by rain. Any suggestions? Rick N6RK ___ Topband reflector - topband@contesting.com
Re: Topband: 2 wire beverage question
- Original Message - From: Tom W8JI w...@w8ji.com To: topband@contesting.com Sent: Wednesday, November 28, 2012 10:49 AM Subject: Re: Topband: 2 wire beverage question ON4UN states in his book that the wires for a 2 wire reversible beverage must be installed side by side, but also may be placed one above the other with satisfactory results. Did someone try this? How satisfactory is satisfactory? There is no difference at all. If the feed system is right, and the line is properly constructed, it would all work virtually the same. It does not matter if one wire is above the other, or if they are side-by-side. Absolutely the best construction method would be a twisted or transposed line, twisted or transposed at fractions of a wavelength, but even using the best twisted or transposed installation it would be difficult to tell from an untwisted line if the conductor was very close spaced (a few inches or less). What does make a difference is the wire used, and how the line behaves as a transmission line. I would not use telephone, insulated wire twisted pair, or field phone wire, because they are very poor transmission lines that are lossy and heavily affected by water. ** Ive noticed no difference in any weather using field phone wire which happens to be in wide use by many very competitive contesters and lowband DXers. With 5 2 wire reversibles here and 750' of 1/2 feedline there is no need for a preamp. The galvanized thin fence wire you often champion is also lossy. Carl KM1H ___ Topband reflector - topband@contesting.com
Re: Topband: 2 wire beverage question
Subject: Re: Topband: 2 wire beverage question ** Ive noticed no difference in any weather using field phone wire which happens to be in wide use by many very competitive contesters and lowband DXers. With 5 2 wire reversibles here and 750' of 1/2 feedline there is no need for a preamp. I'm talking about: 1.) impedance change 2.) reactance caused by loss Since the impedance presented at the far end of the antenna (in termination mode) varies with weather and is reactive (with high and variable dielectric losses), termination can be unreliable. I think you worry too much about minor things, even the much more expensive 450 Ohm window line is affected by rain. Spend more time establishing good ground connections and less worrying about rain. Maybe that's why you think I have a remote receiver :-) ? ** Ive no idea what that is supposed to mean? The galvanized thin fence wire you often champion is also lossy. That's an apples and oranges comparison. First, I don't champion galvanized wire. That aside, there is nothing wrong with using it in normal Beverages of reasonable length. ** You have suggested its use many times. It is not terminating the system for F/B, and the termination impedance and loss does not vary with weather. ** So now you have modified your stance by saying not to use it for a 2 wire Beverage? I wonder what the loss of steel fence wire and WD-10A is per 100' at 160M?. At $40 for a new 2.5km reel of WD-10A Im not about to let a little rain bother me even if it did upset things a bit which I doubt is enough to be noticable anyway. Carl KM1H Carl KM1H ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2629/5424 - Release Date: 11/28/12 ___ Topband reflector - topband@contesting.com
