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Beverage receiving antennas




 
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KZ5A
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« Reply #25 on: August 30, 2011, 04:24:50 PM »

I should spring for a new copy of EZNEC, mine is EZNEC 3 and is umpteen years old, and doesn't model ground systems very well.

The article is in Oct 2010 QST by Tony Preedy G3LNP.  My copy seems to have escaped me so I need to hunt for another.

A schematic is at....

http://www.flickr.com/photos/79358868@N00/5212370224/

I didn't try to model the transformers, feed lines, and remote termination.  Just modeled with local feedpoint and termination.

Beverages, I'm sure, are great if you have the acreage.

73 Jack KZ5A



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Steve - K4HX
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« Reply #26 on: August 30, 2011, 07:02:25 PM »

I've talked to Tony many times on 80 meters and once or twice on 160 metet phone. His article cover his version of phasing two loops to move the back side null. Pretty neat stuff. I've thought of trying his design. Could be very powerful for getting rid of some QRM. Let me know if you need the article. I think I still have the hardcopy here.

How much space do you have? Depending on your requirements, you may have the space you need for a Beverage.
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Bill, KD0HG
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« Reply #27 on: August 30, 2011, 07:32:22 PM »

If no space, I'll add my pro comments sbout shielded (or not) loops.
A tuned 4-footer in the yard is steerable and has terrific directionality.
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WA1GFZ
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« Reply #28 on: August 31, 2011, 10:20:23 AM »

http://www.hizantennas.com/ check this out
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KZ5A
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« Reply #29 on: August 31, 2011, 12:05:35 PM »

About as close as I could get to a Beverage would be about 175 to 200 ft oriented E-W.   The angle for Europe is not there on this lot.

Small tuned loops look like an interesting option and I will probably get around to trying one.   My impression from various articles is that the K9AY may be better from a SNR perspective.  

Although I've been a ham for almost 50 years this winter will be my first serious venture into low band operating so it's all one big learning curve and I'm enjoying it.   The antenna "farm" will be a 50 ft roof mounted vertical that is remotely switchable for 160/80/40, a sloping 160/80/40 trap dipole running SSW-NNE, and the rotatable K9AY.   I expect the vertical to be primarily a TX antenna, its up now but is noisy as Hades on RX.   The dipole is on the ground waiting for me to get a support rope up 70 ft in a pine tree.   All the parts for the K9AY are on hand and I'll start on it as soon as the dipole is up.

The orientation for the dipole is "non-optimal" and I'm hoping the slope will give it adequate utility to the NE.  It may get converted to an inverted-V later.

The K9AY is not the "best" low noise RX antenna around but it looks like the champ from a cost/benefit consideration.

73 Jack KZ5A
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k4kyv
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« Reply #30 on: August 31, 2011, 12:18:28 PM »

If no space, I'll add my pro comments sbout shielded (or not) loops.
A tuned 4-footer in the yard is steerable and has terrific directionality.

I have a 5' square shielded loop  built per the 1970s ARRL antenna book. The null is so sharp that it could be considered omni-directional, but if it can be rotated some noises can be nulled out very effectively. It often is less noisy than the vertical on 160m. It also works on 80m with the trimmer cap run all the way out. It is now on a rotatable frame inside the shack, but with all the other metal and wiring in close vicinity it is of limited use. When the "shack" was in the main house, I hung it on the wall like a map, and it still usually pulled in signals better than did the quarter-wave vertical.

A couple of times I took the rotatable version outdoors, well away from the shack, and using my R-1000 with a long extension cord, was able to get excellent result nulling out a lot of (but not all) local noise, but it seemed virtually omnidirectional to sky-wave signals (totally ineffective in nulling out QRMers).  I have an old TV antenna rotator, so maybe I should try to get it working and move the loop outside. Problem is, the tuning is very sharp, so it would require another remote tuning device with reversible motor to make it work in more than one segment of the band.

From what I have read, the K9AY loop, Flag, Pennant, EWE, etc. are basically two-element phased verticals, with a  cardoid pattern rather than figure-8, and the nulls are not razor-sharp like the shielded loop, allowing them to better null out the noise. I picked up a bunch of 4-ft fibreglass  rods at Dayton one year with the idea of using them to support a K9AY or similar antenna, but have had greater priorities and never started  the project. It appears feasible to build a rotatable K9AY loop if you have the uncluttered space to rotate it and anchor it down in the chosen direction.

I built up a K6STI Loop from the original Sep 1995 QST article, but it turned out to be a big disappointment. No more 'low noise' than a random piece of wire tossed out the window. About the only use it ever was to me was to provide the motivation to build the beverage, which has given good to excellent results. The thing is a PITA to mow around, but I haven't taken it down, thinking maybe some day I'll play with it some more and see if I can make it work better.
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Don, K4KYV                                       AMI#5
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« Reply #31 on: August 31, 2011, 01:05:47 PM »

A couple of times I took the rotatable version outdoors, well away from the shack, and ... was able to get excellent result nulling out a lot of (but not all) local noise, but it seemed virtually omnidirectional to sky-wave signals (totally ineffective in nulling out QRMers).

Yes. Small loops at certain low heights only have the deep null at very low angles. I just discovered that this week while playing with them in EZNEC+.

This is shown on Fig. 2 on http://www.w0btu.com/magnetic_loops.html (the first 3D plot as you scroll down a little). Note that the deep nulls along the X axis decrease dramatically as the elevation increases.
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Steve - K4HX
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« Reply #32 on: August 31, 2011, 03:55:29 PM »

Quote
About as close as I could get to a Beverage would be about 175 to 200 ft oriented E-W.   The angle for Europe is not there on this lot.

Too bad about the angle/orientation. You definitely want NE for Europe. A pair of 180 footers phased would be superior to the K9AY. But go with what you got and have fun. Hope to hear you on the bands.
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KM1H
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« Reply #33 on: August 31, 2011, 04:52:35 PM »

Use 5 of the larger metal Slinkys stretched out over 150', soldered end to end, and you have almost the equivalent of a full wave on 160. Termination here in very poor soil is 1200 Ohms found by aiming directly at a groundwave BC station at 1590 and using a carbon pot to null. Use a binocular core transformer to match the feedline.

Steel rusts so give it a good coat of your favorite rust preventer paint or spend the extra bucks for the brass version.

Ive found them to be quieter than a copper wire one a few hundred feet away possibly due to the RF resistance loss but very seldom was a preamp needed on 160/80. It worked fine to 30M and even on 20 when the snow static took out the yagi.

Carl
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W0BTU
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« Reply #34 on: September 01, 2011, 12:25:48 AM »

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Beverages are supposed to be their best with low or non-existent ground conductivity.

They don't work over saltwater, that's for sure!

Generally speaking, the higher the ground conductivity, the longer the Beverage must be.

Mostly irrelevant at HF. The incoming wave is not at zero degrees elevation angle, so the lossy earth is not required to induce phase delay. Differences in ground conductivity just mean the termination resistance will need to be different and/or the height can be different for a given amount of gain.

Whether lossy earth is required for phase delay or not, I don't know. But one thing is for sure: A Beverage HAS to be erected over earth that has a certain degree of losses. A Beverage will absolutely NOT work over highly conductive earth, such as a salt marsh near the ocean.

(And either will a Beverage work if we run wires under it. Numerous reports from people who tried to follow W1WCR's advice testify to that.)

There have been countless experiences of hams who put up a Beverage over the ocean (or over areas with salty, highly conductive ground), and nobody --not one single person or group on a DXpedition-- has ever had a Beverage work over that type of earth. Without exception, when you read the many experiences of people who have tried that, the result is utter disappointment. In each and every case, those Beverages were absolutely worthless, period.


Now, I made the statement here that "Generally speaking, the higher the ground conductivity, the longer the Beverage must be." I based that mainly on the experience of one person, and perhaps I'm wrong there. Most people who have tried longer and longer Beverages reach a point of diminishing returns. But K5RX, the one guy with the 10 to 15-ohms-per-ground-rod earth (that's much better earth conductivity than average), reported an observation consistent with the long-held idea that Beverages work better over poorly conductive earth. That's why I said that. (See http://www.w0btu.com/Beverage_antennas.html#How_Long)

One thing is for sure, there is disagreement over exactly how Beverages work on HF. Some highly respected people say there is no such thing as wave tilting. N5IA (near the end of my Beverage page) gives the interesting analogy of the Beverage being a transmission line that works because one of the conductors is more lossy than the other; but other respected people say that's nonsense. I can't say for sure, because I don't know. I try and keep an open mind about all this. But one thing is for sure: As long as Beverages aren't installed over salty earth, they work very well indeed, and that's all that really matters! :-)

Quote
The K9AY is a terminated loop. It's in the same family as the EWE, Flag, and Pennant.

Interesting page about those antennas at http://www.w8ji.com/k9ay_flag_pennant_ewe.htm
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Steve - K4HX
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« Reply #35 on: September 01, 2011, 09:15:41 AM »

Quote
Whether lossy earth is required for phase delay or not, I don't know. But one thing is for sure: A Beverage HAS to be erected over earth that has a certain degree of losses. A Beverage will absolutely NOT work over highly conductive earth, such as a salt marsh near the ocean.

I'm not discounting past experiences, but why is this so? Why is lossy earth needed at HF (and if you think about it, all earth is lossy)? Did these people try extensive tests at the higher HF frequencies? Did they do the proper tests to determine the termination ressistance? Or did thay just run out a set length of wire and use a set termination resistance and then decide that it didn't work.

Since most of use don't live on or near a salt marsh, this is a rather moot point anyway.  Smiley
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KM1H
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« Reply #36 on: September 01, 2011, 11:06:29 AM »

Its very simple. A Beverage is vertically polarized.

The loss is there to force the incoming wave to tilt which then imparts a voltage on the horizontal wire. The more the tilt the shorter it can be which is why a 150' Slinky works so well. A Beverage is also called a slow wave antenna and for good reason.

Over saltwater there is no tilt and all you have is a horizontal longwire with frequency sensitivity. A Beverage is non resonant altho over some grounds they do show some SWR variation. On my rock pile its minimal.
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WA1GFZ
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« Reply #37 on: September 01, 2011, 12:08:19 PM »

I tried phasing a couple loaded delta loops and got some great nulls in front but back null side I had very little control so it will take 4 antennas, two for East and two for West. I have variable phasing with the K5SO HPSDR diversity program
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WD8BIL
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« Reply #38 on: September 01, 2011, 01:06:51 PM »

Ground stability, as in losses, is a parameter that's really important in beverage function. A stable ground impedence will perform more predictable than one that varies greatly with changes in weather.
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Steve - K4HX
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« Reply #39 on: September 01, 2011, 01:35:02 PM »

That makes sense at LF. It does not make sense at HF. The wave is already tilted, so why would lossy ground be needed?

Its very simple. A Beverage is vertically polarized.

The loss is there to force the incoming wave to tilt which then imparts a voltage on the horizontal wire. The more the tilt the shorter it can be which is why a 150' Slinky works so well. A Beverage is also called a slow wave antenna and for good reason.

Over saltwater there is no tilt and all you have is a horizontal longwire with frequency sensitivity. A Beverage is non resonant altho over some grounds they do show some SWR variation. On my rock pile its minimal.

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k4kyv
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« Reply #40 on: September 01, 2011, 01:52:42 PM »

Ive found them to be quieter than a copper wire one a few hundred feet away possibly due to the RF resistance loss but very seldom was a preamp needed on 160/80.

I have never needed a pre-amp with any of my  receiving antennas.  The beverage is only about 20 dB down from the full size dipole or vertical, and I often use a 20 dB attenuator pad with the vertical to prevent broadcast station intermod.  Even the 5' square shielded  loop works without a pre-amp as  long as it is tuned to  resonance.

I have a nuvistor pre-amp, but I took it off-line.  It amplified the signal, but also amplified the noise by an equal degree, plus the noise and intermod that it contributed.  I found I had a better s/n ratio without it.

Maybe the 75A-4 was built with too much rf gain at the front end, and would have been cleaner with less. That was a common problem with receivers built in the mid 60s and earlier; back then a lot of people believed the more gain the better, but couldn't figure out why they had cross-modulation.
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Don, K4KYV                                       AMI#5
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« Reply #41 on: September 01, 2011, 03:44:45 PM »

Quote
That makes sense at LF. It does not make sense at HF. The wave is already tilted, so why would lossy ground be needed?

Where is the magic dividing line? How much is a vertical wave tilted over salt water?

If its only a LF antenna we all might as well tear down our Beverages. The tilt imparts the directivity and if you make a Beverage too long it will reverse direction

Just because it was developed at LF doesnt mean it can only be used there.

With that sort of thinking yagis would never have progressed above low VHF and it took hams about 50 years to try Beverages at HF/MF since the "experts" said it couldnt be done.
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« Reply #42 on: September 01, 2011, 06:08:23 PM »

I have some thoughts about how the Beverage works at HF, but they haven't yet congealed in my head to the point where I can explain them as I would like to. Regardless, here are some observations of mine, and I'd like to hear what you think of them, good or bad.

About the only significant difference between a Beverage and a high longwire of the same length is the height. The patterns are the same, at least at HF. Since we can't terminate a high long wire (the vertical feed and ground leads would pick up more signal) and compare the pattern to a Beverage, let's compare an unterminated Beverage to a high wire of the same length.

I just modeled a ~100' high unterminated 580' wire @ 1.8 MHz in EZNEC. It was a single wire with one source right at one end, over 'real' earth. Its lobe shapes and F/S ratio was not unlike that of my terminated 580' Beverage 10' high (image attached).

It's the pattern --those narrow lobes and nulls-- which give a Beverage (or an array of phased verticals, for that matter) its greater S/N ratio, and therefore an edge over a dipole or vertical at HF, isn't it?


Most Beverages are terminated, and have only a single lobe (and therefore a F/B ratio) because of that termination. I left the feedline and termination off in the longwire model because when we raise a Beverage up to the height that a typical long wire might be, we have much greater --and undesired-- pickup on the vertical portions on each end. It wouldn't have been a good comparison.

However, this doesn't explain why so many different people --many of whom never knew one another-- have found that they work so poorly over salt water.

What do you think of the analogy of a Beverage to an open-wire transmission line with one lossy conductor? This is what N5IA said:

"In the most simple explanation of the theory of operation of the  Beverage antenna you must understand that the single wire above (or on) the ground is 1/2 of an unbalanced transmission line.  The earth conductivity is the other "wire" in the transmission line.

"When the earth 1/2 of the "transmission line" becomes very conductive, the whole array approaches being an actual 2-wire transmission line (perfectly balanced).  When that happens there is near ZERO signal received.

"The more unbalanced the line is, the more signal level is impressed on the wire which can be detected by proper impedance matching to a coaxial feedline going to your receiver.  That is why the Beverage works well over poor earth."


* 580_ft_Beverage_antenna_total.gif (8.7 KB, 404x280 - viewed 595 times.)

* High 580' longwire.gif (15.66 KB, 533x466 - viewed 568 times.)
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Steve - K4HX
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« Reply #43 on: September 01, 2011, 07:19:21 PM »

So, what you are saying is that the incoming wave angle is zero? I've never heard of such a thing at HF, saltwater or otherwise. The point is that tilt does not need to be induced. It already exists because of the non-zero wave angle. The fact that Beverages were originally developed for LF/MF has nothing to do with this fact.


Quote
That makes sense at LF. It does not make sense at HF. The wave is already tilted, so why would lossy ground be needed?

Where is the magic dividing line? How much is a vertical wave tilted over salt water?

If its only a LF antenna we all might as well tear down our Beverages. The tilt imparts the directivity and if you make a Beverage too long it will reverse direction

Just because it was developed at LF doesnt mean it can only be used there.

With that sort of thinking yagis would never have progressed above low VHF and it took hams about 50 years to try Beverages at HF/MF since the "experts" said it couldnt be done.

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« Reply #44 on: September 01, 2011, 07:32:31 PM »

Quote
However, this doesn't explain why so many different people --many of whom never knew one another-- have found that they work so poorly over salt water.

Who are these people and how did they erect a Beverage of salt water? Did they experiment with heights, lengths and terminations?

The lossy earth two conductor explanation sounds very similar, if not exactly what Harold Beverage wrote 80 years ago. He was working at LF/MF.

Even over salt water, the conductivity of the two conductors of the balanced (unbalanced) feedline model will not be equal. The conductivity of copper is  59 x 10^6 siemens per meter. The conductivity of salt water is around 5 siemens per meter. Granted, the salt water conductor could be quite a bit larger or have greater surface area but I'm not sure it would be a million times larger.
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« Reply #45 on: September 01, 2011, 09:17:46 PM »

This is my understanding:

The performance of the Beverage is dependent on the imperfection of the earth conductivity. If the earth were a perfect conductor, there would be no horizontal (tangential) electric field due to a vertically polarized electric field. I looked in the text Antennas, by Kraus, and the statement from his text is “However, if the surface is an imperfect conductor, such as the earth’s surface or ground, the electric-field lines have a forward tilt near the surface as in Fig 14-22 b”.

I think this idea of tilt is really a play on words and is with regard to the figure in the text. If the earth surface were a perfect conductor, there would be only the vertical component of the electric field. There is no bending or tilting of this vertical electric member. In the presence of an imperfect conductor, the original electric field now has both a vertical and horizontal component.  It would appear as though the vertical component is dragged across a lossy surface and this bending creates a horizontal component that the Beverage antenna takes advantage. In the absence of the Beverage, this component would be still present, however dissipated as heat. All of this is simply paraphrasing Kraus.
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« Reply #46 on: September 02, 2011, 07:23:11 AM »

Quote
However, this doesn't explain why so many different people --many of whom never knew one another-- have found that they work so poorly over salt water.

Who are these people and how did they erect a Beverage of salt water? Did they experiment with heights, lengths and terminations?

I don't know the answers to either of those questions. A few years ago, I spent countless hours scouring the web for any Beverage antenna info I could get my hands on, and ran across the experiences of more than a few hams who had tried this. I just remember reading them, and I wasn't interested enough at the time to pay attention to exactly what they did or who they were. I think I read some of them in the Topband reflector archive. If you're interested, I can try and find some of that info, but like you stated, it's really a moot point.

I just looked in the 19th edition of the ARRL Handbook. They say "Beverages operated over saltwater do not work as well as they do over poor ground". (p. 13-17).

The 5th edition of ON4UN's Low Band DXing (p. 7-60) says "The Beverage does not work at all over saltwater. ...this does not mean they do not work near saltwater!. ... another condition is that the ground under the Beverage is not soaked with saltwater."

You make a very good point that the conductivities of copper and saltwater are so far apart. I just don't know the answer.
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k4kyv
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Don
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« Reply #47 on: September 02, 2011, 11:13:17 AM »

The lossy earth two conductor explanation sounds very similar, if not exactly what Harold Beverage wrote 80 years ago. He was working at LF/MF.

Which includes 160m.
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Don, K4KYV                                       AMI#5
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« Reply #48 on: September 03, 2011, 12:53:44 PM »

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So, what you are saying is that the incoming wave angle is zero? I've never heard of such a thing at HF, saltwater or otherwise.

Thats not what I said so stop skewing things.

Quote
The point is that tilt does not need to be induced. It already exists because of the non-zero wave angle. The fact that Beverages were originally developed for LF/MF has nothing to do with this fact.

The point is that the degree of tilt determines the voltage imposed on the wire and also the maximum useable length. A perfectly vertical wave will not impose any voltage on a horizontal wire over perfect ground....theoretically. The length of the antenna determines the lowest wave angle and since this is with lossy ground its impossible to be zero, more like 20* for most of us.

Id suggest investing in ON4UN's book which covers all the bases and would minimize a lot of the chatter and guessing here.

Quote
Who are these people and how did they erect a Beverage of salt water? Did they experiment with heights, lengths and terminations?

Several contesters and DXers many of which were multi-multi stations with an educated group trying everything. W1KM is one who is in a salt marsh on Cape Cod. Its not so much as they didnt work but a well tuned 4 square was better for SNR.

Quote
The lossy earth two conductor explanation sounds very similar, if not exactly what Harold Beverage wrote 80 years ago. He was working at LF/MF.

Thats where it all started but there was no such thing as LF and MF back then, using todays arbitrary terms it was all LF operating.
When 1500W became "legal" on 160 the Beverage was brought back to life and studied extensively; eventually by software.



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« Reply #49 on: September 03, 2011, 07:23:16 PM »

Great thread...I have recently hooked my two remaining beverages back up for the winter low band season coming up..The "Cal beverge" is 585 +/- ft long copper clad steel over uneven rockpile terrain mostly about 9 ft above ground ....Unterminated.....Oriented south and a little east...Strung as a single span between 2 large pine trees....Fed to the shack thru a 8 to 1 transformer (ungrounded) and 75 ohm CATV (RG 59?).....I hear the west coast , especially California very well on this antenna....I used it terminated with 600 ohm carbons for a while but when I was trying to hear Europe on the low bands I needed it bi sexual...so I took off the termination..The other Bev is about 450 ft long and is unterminated oriented E and W..Bi directional,About 9 ft above ground..Fed to the shack thru a homemade 9 to 1 transformer mounted in a can on the side of the shack..75 ohm triax audio line is the feedline...This antenna is over a black dirt grass meadow and hears out to the east very well ....Attached pictures are of my beverage feedpoints...The transformer in the can got a brush out of the insect debris and the transformer in the Jar got a new Jar , new coax and connections cleaned .....I am interested in real ham reports from users of the K9AY...Haven't got to try one yet...


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