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Beverage Antenna information site - input needed

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by W0BTU, May 2, 2011.

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  1. W0BTU

    W0BTU Ham Member QRZ Page

    I have made quite a few changes to my Web page about Beverage receiving antennas recently, and I would appreciate any input (good or bad) concerning it.

    It's at http://www.w0btu.com/Beverage_antennas.html. I created that page because I found that there was no single source that you could go to if you wanted to build a good bi-directional Beverage antenna. We're not quite there yet, but that is my ultimate goal.

    After reading it, What information is missing? What questions does it leave unexplained, etc. ?

    It's tough to do a good job of explaining something that you are very familiar with. For example, I wrote an instruction manual for a product that I helped develop for the packaging industry almost 20 years ago. It was a disaster. When I flew around the country for that company visiting their customers, I found that a lot of technicians simply did not grasp a number of important points that I was trying to explain. It helps a lot if the end-user --who is not intimately familiar with something you've helped develop-- has some input. That's why the programmer should never be the sole author of the manual for the software he wrote.

    Well, I certainly did not invent the Beverage antenna, but I'm sure there are things that I could have explained better on that page. Any suggestions would be more than welcome. :)
     
  2. KM1H

    KM1H Subscriber QRZ Page

    A couple of things come to mind Mike.

    Yes, they work very well down to frequencies they are not supposed to and still have excellent directivity and sensitivity. I used four 2 wire reversibles over the fall and winter that are 600-900' long including being able to seperate foreign BCB on the same frequency down in the 150-280KHz band. At 200KHz 600' is .12 wavelength! Ive since added a fifth 2 wire as there are so many countries now on 160 that even being 3dB down on the peak may hurt.

    Mine run thru the woods so I use trees for supports for the black electric fence insulators which are cheap by the bag ($3.99/30) at a local feed and grain store. A 1-3' variance from perfectly straight hasnt hurt performance based on the past 6 months of using them. I see an average of 12-15dB F/R worse case and 20-30dB often using an S meter that Ive plotted its real response.

    That first sentence is confusing to me, maybe not to others. A Beverage has a self impedance of around 470 Ohms over a near perfect ground so the transformers (or resistor for a single wire) should be designed that way for that example. Ground resistance varies a lot around the country and planet so 470 Ohms is not a magic value for best performance.

    My RF ground is right around 200 Ohms over about 10 acres of flat land where solid rock is 1-3' down. What ground there is is all bony sand below the 4-6" of topsoil. Im on the top of the highest hill in the area which makes for a great ham location but a good ground is not a feature. In fact I use elevated radials on 160/80 verticals to high advantage.

    When calculating the transformer ratios or resistor value you have to subtract the RF ground value from 470 Ohms. I use 250-270 Ohms and have watched the difference between a good match and a haphazard one on HP 3586B selective voltmeter and also the effect of a 250 Ohm transformer at one end and a 470 at the other. A 259B is also used. To say I did a lot of walking is an understatement!

    Ive been using mine regularly thru 30M and they still show life on 20 but with my poor ground resulting in a slower wave front and more tilt its beyond the point of no return. A seperate shorty for 10-20M would probably work well. At a prior QTH I used them up to 10M.

    For best performance over several bands as well as high primary to secondary transformer isolation the BN73-202 is the way to go. Instead of the sleeve you show I install 2 sleeves per hole and wind the primary in one and the secondary in the other. The sleeves are Teflon since I had plenty of very small tubing on hand but its not fussy. The difference between all the wire together, one sleeve, and two sleeves ranged from 9-10pf to 1-2pf. This increase in isolation makes for high directivity and reduced common mode or local noise pickup. I use #26 or 28 magnet wire with no apparent difference and no preamp is required even with a 750' run of 1/2" CATV hardline from the far hub.

    Im using individual feeds for now and Ive been unable to detect any difference with the unused side floating or terminated with the one coax pair that comes directly into the shack; that may be a feature of the low C and high isolation of the windings. When I revise things with the new switching configurations and hubs I'll include the resistor anyway.

    You "must" stress several times that feeedline and antenna grounds be kept seperate for common mode isolation. Right now my only feedline grounds are back at the house or at the hubs. Adding another 50' from the antenna grounds is planned soon to see if it helps or hurts.The feedline end of the antennas is 30-200' away from the hubs.which are 500' apart.

    I suspect that close wire spacing helps as does a regular twist. I cant prove this so others may have other ideas. One antenna is very vintage rural telephone wire, a pair of #14 copperweld in a thick rubber jacket that Ive had stored for maybe 35 years on its reel. Impedance calculates to 175 Ohms. The others are all US Army telephone wire but not the overpriced stuff sold at .10/ft or more; Id be broke using that stuff but it is apparently rugged. The stuff Im using is cadmium plated #22 stranded copper that comes in 2 pairs per 1000' reel. That gives two 1000' reversibles for the current Fleabay price of $17 + shipping from the West Coast or $25 plus shipping from Ohio. It comes out to $40-41 total to NH for either but Ive been buying from Ohio. The impedance is 93 Ohms. Both size lines twist naturally during the install as does window line.
    Its been strong enough to survive a brutal winter with no breakage, the insulators are about 30-40' apart. I suppose a small messenger rope and tiewraps could be used for long freespan runs.

    A good ground is not imperative but a steady one is in order to have year around equal results. Nowhere is an adequate ground specified, "a couple of short radials" is about as detailed as it gets. Im using three 4' rods spaced 6-8' apart in a Vee in front and behind the antenna. These are 8' rods cut in half and driven in at an angle as I did with the original Beverages here 22 years ago; most have been reused as they show no sign of rust. Radials are four 20-30' #24 insulated wires for each rod and the total covers a fairly big area. In the past I used a single rod and 2-3 130' radials which also worked very well with single wire terminated Beverages altho some say they dont. Anyway on the ground they are not resonant on 160.

    My Beverages range 4-7' high and I dont need a ladder to install them...thank you; the 4' one is all on my own property. Deer havent bothered them either and the surrounding woods is all posted No Trespassing, etc and runs up to 2 miles in a few directions. Im on my own 5 acres which abuts a neighbors 220 acre property which Im allowed to use.

    A BOG is not made from coax, that is a Doug DeMaw "Snake" and is useless as designed as is a lot of his stuff that was published. My 900' 2 wire is fed right at the property line of a yuppie neighbor with a zillion bucks of yuppie electronics plus 5 kids. Unfortunately it is the SW end of the NE/SW run which terminates about 30' from a town owned fire road in the oppisite direction so I didnt dare try and run it on the other side and well into the boonies which is owned by someone I dont know who lives out of state. So I ran a real BOG in parallel with the 2 wire and about 12' away for 660' to the back hub. It has a 270 Ohm resistor and the same ground system but steered away from the elevated antenna ground area; no overlap. While the yuppies are awake its a buzz saw on the bands but nothing is very loud in any DX portion of 160-30M but it is enough to mask pee weak DX. The BOG runs from about 0 to 12" above ground over low growing ground cover and is made of 5 scrap lengths of #10 to 14 stranded and insulated wire.
    Performance amazed me. Signal levels are often about equal to the 2 wire and the local plus band noise is lower; no preamp. It does appear to favor a higher angle signal and is usually my choice until the yuppies are in bed. On some morning grayline paths the BOG is a bit better but its hard to tell; I really need to combine the 2 and see if that works better as constant switching is a PITA.......but that is easier said than done due to the location of the 2 hubs and the switching that entails. For now they stay independent until I decide I want to reverse the 2 wire feedpoint and run a 300' hardline feed to the back hub which will then have to be expanded and modified....it never ends!

    No room for a traditional Beverage? Then try a Slinky. I had 5 of the large ones in series over 150' for almost 20 years and it was a solid performer; very quiet likely due to the steel wire loss and a preamp was used. At that time it was my only option for due East/SE where a lot of good DX comes from and I worked a lot that locals couldnt hear, rear rejection was excellent. A K9AY wasnt even close. The Slinky rusts fast in this area and either requires yearly replacement or a good rust preventer paint. They also have brass ones that are a lot more expensive. A planned project is a pair of staggered and phased Slinkys E/SE to see if I can knock down pileup QRM from lids and alligators.....I wonder if they can be switched to reverse direction? Havent studied that yet. Tests with a lightweight SS radio and using a BCB station right off the rear resulted in a null at 1200 Ohms so thats what I designed the transformer for...no 259B back then.

    Back then I had only uni directional single directions, some 2 wire experiments using a useless book for guidance were a disaster. Thats the same publication you mentioned using the wire under the antenna and a floating downlead. No wonder Beverages got a bad name and that ground goof in ON4UN's was another head scratcher. Thats when I sat down and got serious and did all my own tests. I call each one of the ON4UN books a Revision, and not an edition as there are so many mistakes, bad proofing, bad ideas, etc. Havent read Rev 5 yet, its out of stock at the local HRO. Id really like a copy of the CD from someone so I can see if its even worth buying.

    Just remember that my results may not be the same elsewhere, Ive designed and built for my particular ground enviroment.

    Im glad you took me up on the transmitting challenge! At the old QTH I was running 1200-1500' and even tried 2400' (poor towards EU for receive so it went back to 1200') for awhile so 160 worked better than yours.

    Carl
     
  3. KD0CAC

    KD0CAC Ham Member QRZ Page

    I want to plant one , but I need the farm , so gathering info now .
    Thanks
     
  4. W0BTU

    W0BTU Ham Member QRZ Page

    Thanks, Carl! This is great. :)

    For starters, I just re-wrote the section you said was confusing, combining it with another one that was in a different place. http://www.w0btu.com/Beverage_antennas.html#How_far_apart. I was going to draw a picture, but I think the text explains it.

    Just when I thought my transformers were optimized, you come up with a new idea. I like the idea of two pieces of Teflon tubing. I'm using heat shrink tubing, which is hard to insert. Do you know where I can buy some?
     
    Last edited: May 2, 2011
  5. KM1H

    KM1H Subscriber QRZ Page

    I picked up several partial spools of Teflon tubing of numerous diameters at a hamfest years ago, its available new from the usual large parts distributors but probably expensive. Maybe Ebay has some.

    Another thing I didnt like is that only full turn taps were mentioned in binocular core articles, ON4UN, etc and some said it was mandatory. Dont remember which ones as there is so much bad info out there. Its perfectly fine to connect the tap at the center of odd turns which puts it at the other end of the core; Ive done that for decades for other RF projects and they work fine as shown on the VNA. I also keep primary and secondary wires as far apart as possible outside the core to minimize stray coupling, nothing gets twisted either.

    Ive been considering getting a laptop and one of those little VNA kits for work out in the woods inorder to see if tweaking the transformers to perfection adds any improvement to the F/R, there are enough 250W-5KW BCB stations all around me at 5-10 miles to use as sources.

    Carl
     
  6. W0BTU

    W0BTU Ham Member QRZ Page

    I don't either. But I use one. My thinking is that it is more related to coax length, but maybe you have a point.

    Excellent point, Carl. I just did that.

    I'll have to go back and look at the book again, but I thought ON4UN's 4th edition did a great job of explaining the difference between a coax BOG that works and Doug's "snake". Are you saying that John didn't?

    I plan on using some more of your suggestions on that page. But since I've received so many requests for more photos of my newest Beverage antenna control boxes, I'll probably put those up there first.

    I can't believe how popular that page has become. To me, it still needs so much more work.

    Thanks again, Carl! :)
     
  7. W0BTU

    W0BTU Ham Member QRZ Page

    FWIW, the 5th edition of ON4UN's book particularly stresses the 'need' to not use half-turns. And he's practically doubled the number of turns in his transformer designs there, just to get ~1 dB less loss. Not to take anything away from what John has published over the years, but I take issue with the need to do that for a Beverage antenna transformer. You have to eliminate the liner and use very fine Teflon insulated wire to accomplish that.

    Let us know what you find. That sounds great.
     
  8. KM1H

    KM1H Subscriber QRZ Page

    Who the hell would waste money on coax just to toss it on the ground? You checked the prices? And then in a few months it would be garbage once the critters got into it. I had to repair my BOG in 2 places where the #10 stranded was chewed right thru. It must have happened right after the 4' of snow melted as it had been fine before and suddenly the signal dropped and there was no more F/R, the first bite was about 200' from the feeedline.

    And so does the 4th REVISION, I guess it will soon be time for another $50 scam by the ARRL money pit. All the added turns will do is improve the LF end (to no benefit) and screw it up at some point on HF. I did the extra turns thing in a few steps and saw no useable gain benefit (well under 1dB) on the test equipment and it increased the C a bit. I wonder where John gets his information from:rolleyes: Id rather have a bulletproof 10dB 1-2dB NF premp at the hub or feedpoint for those rare ultra quiet nights if I had much feedline loss. However the 750' of 1/2" hardline here barely has 1dB loss at 40M and its virtually nil on 80/160 so its nothing Im going to lose sleep over. The preamp here is in the shack and I found no need for it for the 6 months the new antennas have been up, the binocular cores are an improvement over autotransformer baluns using FT141-43 mix toroids which Id been using for close to 30 years here and at a prior home.

    Carl
     
  9. W0BTU

    W0BTU Ham Member QRZ Page

    Well, I get flooded Commscope quad-shield RG-6 in 1000' spools for well under $100 shipped. At least at this QTH, nothing's happened to it, and plenty of it is lying on the ground. That is, what the neighbor's horse hasn't stomped down below the surface. :)

    W8JI says that a BOG doesn't work everywhere. I probably won't ever try one, but you never know.

    I have never used my preamp since switching to those cores, either. The signal levels are amazing.


    Anyway, I can't think of any other changes to make to my Beverage antenna page. (Maybe a section to credit all my sources, but I can't think how to word it.) Thanks to everyone for all their input.
     
  10. KM1H

    KM1H Subscriber QRZ Page

    Thats been said long before and the reason is still the same.....RF ground resistance affects the wave tilt. If you have real poor ground the point it reverses direction or simply becomes very lossy varies.

    A steel Slinky is similar due to its own losses as are galvanized fence wire Beverages. But now you have conductor plus ground losses involved. Maybe a Slinky or steel wire over a salt water swamp would work??

    I always took the published comments that a BOG was no good until I tried one out of curiosity. Ive also learned to not believe everything that is published either, even by the "experts". A few seem to dliberately enjoy leaving out bits of crucial info and then point you to some ridiculously overpriced commercial black box or come out with aother pricey manual Revision. If you can include enough DIY info on your site so that anyone can build accurate transformers it would be a big help. A link to a transmission line calculator for starters. Here is one thats been around awhile, I dont know who did it. http://www.csgnetwork.com/antennaerpcalc.html But its got it all in one place, no need to do a bunch of seperate steps.

    Here are some other interesting links:

    http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=19733

    http://www.maxmcarter.com/classecalcs/index.html

    http://www.elisanet.fi/oh3xr/OH2BEN_Reversible_Beverage_Array-20-10-2007_04d.pdf

    http://www.wa4dsy.net/filter/filterdesign.html

    http://www.mayaparadise.com/kw2p/calculators.htm

    Carl
     
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