Beverage Question

[Bill, KD0HG]

From some of the other discussions here, I get the impression that at the antenna's matching transformer, the shield of the coax feeding the receiver should *not* be grounded, but should be left floating.

Seems counter-intuitive, is that correct?

[Todd, KA1KAQ]

I would think you'd ground it at both ends too. The only thing I recall about grounding is when you want the antenna to be bi-directional, but that has to with the antenna itself.

HUZ is one of the guys on here well-schooled, once he shows up.

[K1JJ]

Bill,

The floating coax is connected to the primary of the ~1:9 ferrite transformer. Use isolated pri and sec just like a standard HV transformer does, not one of those autotransformer baluns. (unun)

The secondary of the 1:9  gets connected between the ground rod (with short radials) and the Bev wire itself.  At the opposite end, the Bev wire, if terminated, is connected to the ~600 ohm resistor and the other end of the resistor goes to a rod with radials too.

Adjust the number  of turns on the matching transformer so that a sweep of swr from 160 - 40M is less than 2:1 or better, the broader the curve, the better. You want a flat sweep to indicate the termination resistor is optimum. I believe I used about 3 turns pri and about 9 turns sec and 600 ohms for my particular installation, but you need to match it depending on your own condix.

The floating coax reduces common mode imbalance which can result in local line noise pickup of various sources.


I just installed a 550' terminated Bev to the NE and find it receives as well as my high quad loops on 75M, better than my 160M dipole on 160M, as well as my 40M stack and not as well as my 20M stack. It is an absolutely marvelous RX antenna! Try to run it over flat ground and keep it level and low, like 6-7' high.


Study what W8JI has to say about the subject before moving on:
http://www.w8ji.com/beverages.htm

And here's very specific info from W8JI about common mode you axed about:
http://www.w8ji.com/common-mode_noise.htm

I did an overkill on my system by adding a series of choke baluns on the feedline (on the ground) and also installed a separate ground rod about 20' from the Bev feedpoint which is tied to the coax shield. JI discussed this technique to further attenuate common mode problems.


And finally, follow these rules:

Lay feedlines on or bury them in the ground so earth losses reduce shield current
Be sure shield connections are good
If noise levels are high or antenna sensitivity is very low, isolate the feedline from the antenna as it approaches the antenna by using choke baluns
Ground the feedline a few dozen feet away from the antenna
Avoid autotransformers. Instead use isolated primary and secondary winding transformers
Use an independent ground on the antenna. Do NOT connect it to the coaxial cable shield

T

[Bill, KD0HG]

Avoid autotransformers. Instead use isolated primary and secondary winding transformers
Use an independent ground on the antenna. Do NOT connect it to the coaxial cable shield x. I need to rebuild the beverage before winter.

I'm gonna lay some 500' of RG-58 down to feed an 800' beverage some 8'-10' up on agricultural T-Posts.  Aimed around 45 degrees from here. For Eu (LOL!) W1, W2@ and W3. Into the R-390A.

Then, maybe I  can maybe hear some of you PissWeak Easties.

[KL7OF]

Bill...800 ft may not be the optimum length for you....check out "cone of silence" lengths for beverage antennas..I played around with these lengths and found an improvement over random length beverages..I agree with Tom that 7-8ft is about the right height above ground.....I recommend the book LOW BAND DXING by ON4UN...good luk...Steve

[Steve - WB3HUZ]

You'll be shocked how much better you'll hear Bill. Many of the West Coast stations I've worked in the past few years would not have been heard on my dipole.

The reason for the isolated windings and not grounding the side connected to the coax is to avoid/prevent common-mode noise from flowing on the coax shield and reducing the effectiveness of the Beverage.

You don't need to worry about the quality of the ground at the termination end. Any extra ground resistance will just be part of the termination. You can adjust the termination value accordingly. If the ground resistance changes, then radials or chicken wire is required.

Several ground rods at the transformer/feed end are advisable. Here any extra ground resistance just makes it that much easier for common-mode noise to become a problem.

Don't worry about the length. Cone-of-Silence lengths are not cone of silence at all. They are just lengths (and it will vary with ground conductivity and height above ground of the Bev wire) where the geometrical front-to-back ratio peaks. But this is of a little meaning in the real world. If you do want to reject noise off the back side, then the pattern over the entire back side is the measure of usefulness. Looking at the pattern this way, the pattern gets "better" (more overall backside rejection) as the Beverage gets longer, up to 2-3 wavelengths. Any length is just as good as any other when they are within 50-70 feet. The longer the better.

Further, longer Beverages have a lower take-off angle, less high angle response and a more narrow pattern in the azimuth plane. If rejection of noise of the back is not the over riding concern, the the more narrow the front lobe, the better the Beverage will hear (it will reject noise better). So, once again, longer is better.

[K1JJ]

Speaking of the ground rods for Beverages...

I found a simple and quick way to do this.  Go to Home Despot and pick up an 8' copper rod for about $9. It's actually a copper plated steel rod.  Cut it in half making two 4' lengths. Grind the ends to make them pointed.   If your Earth soil is like mine here, 4' is about the maximum you can drive it down anyway. Plus, RF likes radials for current flow, not a deep rod.

Then take some #14 wire (or whatever you have) and cut it into nine 16' pieces.  Strip the ends and twist them into a rattail on one end. Use a copper clamp (at Home Depot) to bolt the rattail wires to the copper rod. Then use the propane torch to solder the copper clamp and wires to the rod.  You can do this for both rods while on the workbench.

Then pound each rod into the ground.  Pull out EIGHT of the radials into a spoke wheel and tie each wire opposite end pulled TIGHTLY to an alum or steel 1' rod which gets pounded into the ground. The result is a tight, symetrical set of radials surrounding the ground rod - and a reasonably low RF path resistance.

The ninth ground wire at each rod connects up to either the Beverage matching transformer secondary or to the termination resistor.

With this method you have minimum work to do in the field and end up with a great looking installation.

Steve - interesting on your comment about the poor earth ground at the terminating resistor becoming part of the resistor. Never thought of that.  Makes sense. Though, as you suggested too, I would go for a good ground using radials and have a more environmentally stable Earth ground when it gets dry, rains, etc. to keep the match rock solid.  

T

[Steve - WB3HUZ]

A very  FB way to do the ground rod there OM.

[KL7OF]

Steve ...It is interesting your comments on the cone of silence....I found that the rejection of signals from other directions was the feature I was after by changing the length....Or the reception of signals from closer or farther away in the same direction...and I'm talking 300 ft changes  565 to 865 ft..Your comments also indicate that it could be the change in angle of the signals rec'd by the different lenghts.....Thanks for your insight   

[Bill, KD0HG]

Thanks for all the info.  I appreciate it.

I do need to keep the height at or above 8 feet so I can drive the tractor underneath the thing. 8 feet clears the exhaust stack by inches.

The nice thing about using T-posts is it's a piece of cake to use snap-on electric fence insulators, don't need to jury rig anything.

[Steve - WB3HUZ]

Now that I think about it, 800 feet is almost too long for 80 meters, that's like 3 WL. At this point space diversity effects begin to degrade the effectiveness of the Beverage. The distance is so great that the wavefront is not always uniform across the length of the Beverage. Consider running two at 1 or 1.5 WL long, in-phase and spaced about 0.6 WL apart. The pattern from this setup will be superior to a 2-3 WL single wire.

[K1JJ]

Consider running two at 1 or 1.5 WL long, in-phase and spaced about 0.6 WL apart. The pattern from this setup will be superior to a 2-3 WL single wire.

I was gonna sugest the same thang.  I had up a pair of 500'ers phased and found the improved side rejection was huge. There is some power line noise that comes in from the SE here (off the side) when beaming NE/Eur. When I added the second phased Bev, it disappeared.

However, since then, I took that system down and put up a SINGLE 550' Bev that is about 500' farther away from the noise source. It is now quiet with a broader frontal lobe.

Another thing I did was to aim the Bev at 35 degrees, which better favors the weak Russians. Southern Europe is always louder, so it made sense. This same idea can be used when pointing the Bev for stateside. Find the area of most wanted, but weakest stations and favor them, hoping the coverage is broad enuff to cover the louder areas.

Another factor is the Bev shows much better f-b for DX stations at least ~1500 miles away on 75M. The close-in stuff may have little f-b due to the higher angles. Bear this in mind when pointing the Bev too. ie, If you have a troublesome area off the back, the farther it is away, the better the Bev performance for rejection.

T

[Bill, KD0HG]

Been listening for the first time tonight. The bev here is aimed at around 60 degrees, true. Found a T-43 core and wound a matching transformer to feed some 300' of RG-8A/U line back to the shack in the house. 3:1 turns ratio.

There is a 600 ohm termination resistor on the far end, the coax shield is not grounded at the matching transformer.

First impressions on the R-390A:

Extremely quiet antenna. Performance on 75 so far was WA1HLR had a good 10 db S/N improvement over listening on the transmitting antenna (extended double zepp, 300' long at ~ 140 feet).

AM broadcast is amazing. Every station to the NE of here in Colorado kicked butt. From 1110 in Omaha, to KXEL in east Iowa, to all of the clear channels in Chicago, 700 WLW in Cincinnati, all solid Q5+. Even 760 WJR in Detroit was somewhat audible in spite of a 1 KW in Denver on the same freq.

Maybe it's too long for 160-80 meters...We'll find out. I have some snap-on ferrites that I can install on the feedline.

Thanks for all of the tips. I need to find a network analyzer...Before winter wx arrives. Fascinating piece of wire. Should I remove the bird droppings on the insulators?

[KL7OF]

bird droppings are worth a 2 db increase in FB ratio...

[KM1H]

The coax grounding scheme may require some experimenting to minimize BCB intermod and cable pickup. It all depends upon your location.

A couple of AM stations are right in line with 3 of the Beverages here and I wound up isolating the 2 9:1 balun ground wires and use seperat rods about 10' apart. Id said 20' recently but measured the other day when I was out back. Id gone back there to find out why Id been getting BCB intermod recently and found the Ameritron relay box bottom plate all rusted, even under the SO-239's riveted to the steel plate and mounted from the inside. Drilled out the 2 rivets for each connector, seperated the plate from the PC board and tossed into a derusting solution; then drilled 2 more holes per connector, used SS hardware with sharp external tooth washers. Gave all the steel a couple of coats of Zero Rust and a Krylon aluninum top coat, should last another almost 30 years. My other relay box is HB using aluminum that was painted after assembly, thats still OK.

I ground the CATV hardlne at the Beverage and 750' away its simply part of the station interconnect mess which is grounded to the overhead copper water and heating pipes.

Beverages range from 700-1500' and Ive used them at times even on 20M. They helped me confirm the first New England 5BWAZ and the first 160M JA. A tuneable Ameco 6EH7 preamp makes up for the signal loss on the higher bands and adds selectivity; works fine with the gain control backed off to just whats needed. Also isnt bothered by induced lightning voltages that have blown FT-114 size baluns apart.

I wont use phased Beverages as that limits you to one band; mine get used regularly to 30M and 20M as mentioned during snow static on the yagis.

Carl

[k4kyv]

The beverage is no panacea for coping with electrical noise.  Its quietness is due to its sharp directional lobe.  You simply lose the noise coming in from the rest of the 360° of the circle.  Like a vertical, its response is predominantly to vertically polarised signals, which includes nearly all local electrical noise. That's why verticals are so notoriously poor when used as receiving antennas even when they strap on transmit.

In my case, the beverage is aimed approximately to the north-east, which takes in most of northeastern US, eastern Canada, Europe and parts of Africa.  Unfortunately, the intersection of a connector road and the main highway is about a half mile away and located right in the bore-sight of the beverage, and each road has multiple sets of power lines, about 6 phases last time I counted.  When the power lines act up (and you can count on at least one of the lines being noisy at any given time), the beverage often becomes useless and the main transmitting antenna becomes quiet by comparison. In addition, over the past 20-30 years little cracker-box houses have sprung up all along both roads, and I seem to get a lot of rubbish probably from their computers, wall-warts and plasma TVs, even though the nearest house in that direction is about a quarter mile away from the antenna. Also, the fear-mongers at the power company have convinced almost everyone living in rural areas of the county to lease a private street-light for "security", and those things are notorious for crapping out and constantly cycling on and off throughout the hours of darkness. Because of the  layout of the property I can't run a permanent beverage any other direction.

The beverage runs adjacent to the main house and is worse than other antennas, even the 160m vertical, for picking up electrical garbage from the house, generated by the cable modem along with other unidentified buzzies and hash, but at least I can cut most of my stuff off if need be.  If you are fortunate enough to be located where the desired direction happens to line up with few houses and power lines,  the beverage can be a fantastic receiving antenna.

Interestingly, sometimes the noise is frequency selective, particularly on 80 and 40.  One part of the band will be absolutely quiet with no trace of noise, while other parts will be completely obliterated.  Unfortunately, per Murphy's Law, the noisiest spots are nearly always centred right on the usual AM operating frequencies around 3885, 3700 and 7160.

Still, about 60% of the time, I get my best reception using the beverage.  I am still  running it at summertime length, about 400'.  Haven't had time to redeploy the full 900' even though the farmer finished his harvest weeks ago. At full length compared to the shorter version I seem to get slightly better reception out of Europe on 75, superior performance on 160 from all locations, but reception on 40m falls off a little.

I have one of those MoFoJunk noise cancellers although it is not hooked up right now.  The thing is a PITA to null, but under some conditions I have been able to improve the s/n ratio with the beverage as well as the TX antenna.

[Bill, KD0HG]

Man, that thing receives the AM BCB. WLW And WBBM barreling in here at 5 PM, still broad daylight out here.

I just went out to measure it, almost exactly 700' long, straight line, aimed at 50 degrees.

How would I calculate theoretical patterns for different freqs?  I don't think EZNEC would be accurate on a Beverage.

[KL7OF]

Bill...I have a bev aimed at Calif and one aimed due east...I can hear KFBK Sacramento  at +10 and simply by changing to the east bev shut KfbK off and hear a station in Salt Lake at +10...There are several spots on the AM dial where this is possible

I have an unterminated 600 ft beverage running under a 3 phase power line......It crosses at a 90 degree angle ...I do get some buzz on this antenna when the condx are dry..The power line crosses over at about mid span of the Beverage....I haven't used my bevs on 20 meters but I have an Ameco pre-amp and I intend to give it a test drive on 20...

[K1JJ]

Interestingly, sometimes the noise is frequency selective, particularly on 80 and 40.  One part of the band will be absolutely quiet with no trace of noise, while other parts will be completely obliterated.  Unfortunately, per Murphy's Law, the noisiest spots are nearly always centred right on the usual AM operating frequencies around 3885, 3700 and 7160.

The frequency sensitive effect is probably the result of long power lines acting like long wires creating lobes in your direction. As you move your receiver in freq, the power line "antennas" will sum and cancel the broadband noise on any one particular freq.

I happen to be at the dead end of a very long straight street. The line running up from the SE is like a 1/2 mile LW. I can hear the noise rise and fall in a methodical way as I tune up the band.  Fortunately this noise comes in to the side of my NE bev, so is rejected. However, when I switch on my SE wire Yagi it is there as described. Mine comes on when it rains mostly.

The problem with this longwire effect is there is no real point where the noise is located to fix. I've DFed it and find just low level random noise. Evidently all these small sources on the powerline will sum and sometimes really strap when the right freq and lengths of line add....


Bill: Looks like your system is working very well. The AM BC band can be a fooler, however. It is by far the best band to see dramtic f-b and side readings. The readings on the ham bands will be somewhat less cuz of the higher angle signals. I'm also cornvinced that Bevs work best when very low. I would put mine at 3' high if I cud avoid the deer. So on AM BC, 7' is very low electrically.  In contrast, up on 20M it is very high and acts more like a longwire. 20M is the cutoff band for my Bev and does not perform as well as the Yagi stack. On 40M and lower, the Bev is as good as all Yagis on RX.
T

[k4kyv]

I'm also cornvinced that Bevs work best when very low. I would put mine at 3' high if I cud avoid the deer.

Have you thought of constructing a deer-proof wire? Something like #8 copperweld held by a couple of guy wire type strain insulators in series at each end, heavy duty screw-in ceramic stand-offs at intermediate points, using farm type fence posts, and stretching the wire to a couple of hundred pounds tension.  Farmers in these parts run similarly constructed electric fences all over the place.  They often are no more than about 3' high. They are called high-tensile fencing. We have our share of deer.  They  have become infernal pests since the wildlife agency brought them from near extinction in this part of the country, by capturing animals in other parts, importing and  releasing them here.

If the scroteful construction approach doesn't work, try electrifying  the thing when it is not in use as an antenna.

I would  lower my beverage, but a large part runs across the lawn and I don't want a "fence" through the yard, so I run it at 10' to allow people,  lawn mowers, etc. to pass.

You can get some ideas on high-tensile fence construction here. They mention resistance to deer damage.  I would use copperweld instead of galvanised, and of course, HD ceramic insulators instead of stapling the wire directly to the posts.

http://www.kencove.com/fence/4_Why+Build+High-Tensile+Fences%3F_resource.php

[KM8AM]

Try to run it over flat ground and keep it level and low, like 6-7' high.

I'm assuming the comment about flat ground is regarding the change of wavefront angle based on terrain slope. 

Since we're on a ridge, we don't have a lot of flat ground.  We still plan to try beverages for 160 and 75.

[KM1H]

Sloping Beverages down a hill give excellent directivity improvements as reported by many.

Ive got the hill but the sloping is another 1000-2000' away

[K1JJ]

The negative receiving effects I've noticed with my west beverage is when the wire slopes down to the bottom of a hill (stream) and then terminates there. Then the hill slopes upwards 200' in elevation essentially shielding the Beverage from the very low angles. I read that the radio waves do follow the ground, but in my case, this Beverage performed very poorly - sometimes not as well a low dipole out to the western USA. I finally took it down. It was a waste of space.  In contrast, my NE bev that is on flat ground works as well as the 2el delta loops at 190' - it's a killer.

I did have up a pair of Bevs that terminated on the edge of a hill that sloped down for another 300'. That Bev worked very well too, into Europe.  Sloping ground in favor of the antenna is always a good idea to lower the RX angle for DX signals.

So what I'm saying is like any antenna, having a big hill blocking in the direction of directivity might not work too well for DX with any antenna, including Bevs. At least that's my own ham experience. I sometimes wonder how that west Bev wud have performed if I extended it to the top of that 200' hill, though it wud have been longer than I wanted and into land that was difficult to traverse.

T

[W9GT]

The negative receiving effects I've noticed with my west beverage is when the wire slopes down to the bottom of a hill (stream) and then terminates there. Then the hill slopes upwards 200' in elevation essentially shielding the Beverage from the very low angles. I read that the radio waves do follow the ground, but in my case, this Beverage performed very poorly - sometimes not as well a low dipole out to the western USA. I finally took it down. It was a waste of space.  In contrast, my NE bev that is on flat ground works as well as the 2el delta loops at 190' - it's a killer.

I did have up a pair of Bevs that terminated on the edge of a hill that sloped down for another 300'. That Bev worked very well too, into Europe.  Sloping ground in favor of the antenna is always a good idea to lower the RX angle for DX signals.

So what I'm saying is like any antenna, having a big hill blocking in the direction of directivity might not work too well for DX with any antenna, including Bevs. At least that's my own ham experience. I sometimes wonder how that west Bev wud have performed if I extended it to the top of that 200' hill, though it wud have been longer than I wanted and into land that was difficult to traverse.

T

What if you can't run the beverage for the total length in one direction?  In other words, I can only run approx 200 ft. NE, then rest needs to go East?  Would it just broaden the main lobe?  Probably be less effective antenna, but still might help with noise?

73,  Jack, W9GT

[KM8AM]

Since it's downhill on all sides, I'm getting excited about some beverages!