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Beverage on 40M?




 
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WU2D
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« on: October 23, 2006, 07:33:20 PM »

WA1QHQ and myself are putting up Beverages this Fall. I have a good route due west which terminates in a swamp about 800 feet straight back from the basement shack window. Mark and myself want to do a good job on these antennas.

I have done a couple of quick and dirty beverages over that same route before, several years back. My method then was to simply pull wire through the trees randomly at some hieght over my head. The termination was a 680 Ohm 2 watt and the "ground" system was a 3 foot aluminum pipe. I used a simple autotransformer match and fed with RG-58, picking up ground in the shack.  Insulators? Trees are wood - right? Of course the wire broke after one season because it was crap.

The results with even so haphazard a setup were utterly astounding- night and day compared to the inverted L. The Beverages were quiet and very directional to the west. Of course they worked wonders on the broadcast band, 160M and even worked on 80M. On 40M, they lost some of the the magic and above that they acted like a longwire.

This time I am looking for advice on how to do it right. I have a big roll of copperweld and a bag of black plastic electric fence insulators. I want to try an isolated transformer approach with a separate ground rod for the shack side. Can these things be made to work on 40M?

Mike WU2D
 
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K1JJ
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« Reply #1 on: October 23, 2006, 08:08:51 PM »

Hi Mike,

If the bev is much over 350' on 40M, it will start to have sidelobes and pooer side rejection. So, a 160/75M bev that is 700 or 1200' is too long.

The poorer the ground, the better the bev, so they say a swamp or salt marsh is not quite as good for bevs... but any bev is a vast improvement over any vert or dipole for RX. The latest Low Band DXing book has some great info.

I've heard of guys using bevs up to 20M wid good results, though I find 160 and 75M is where they really shine. I don't use mine on 40M cuz it's too long... I stick with a Yagi for hearing.

BTW, I've been experimenting with a PAIR of phased bevs for 75M to the NE/ Eu... 600' long and spaced side by side 180' apart. The side rejection is superb. You could scale that to 40M and have a great system. I wud mount it as low as you can with 4' being optimum. (Watch the deer) I have another 75M to the SE and one to the west. Working the 75M <100W west coast AM guys with it is a breeze when the Yagi is noisy, though most of the time the two are close. Try a dual diversity RX system with the bev and another ant for an extra hearing edge.

Oh, one more thing... you mentioned this, but be sure to float the input transformer at the bev input. The shield and inner to the primary and no ground rod out there. Only a gnd rod at the term resistor and one at the shack. Better for local noise rejection this way.

I will be curious how you make out if you OPTIMIZE a bev for 40M there, OM.

73,
T
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« Reply #2 on: October 24, 2006, 04:13:14 PM »

Tom,

This is my basic drawing. Any comments on this?

Mike WU2D


* BEV1.jpg (6.62 KB, 457x100 - viewed 479 times.)
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« Reply #3 on: October 24, 2006, 04:50:09 PM »

Would it be better to have a string of magic beads on both ends of the coax to keep common mode noise off the antenna ??
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K1JJ
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« Reply #4 on: October 24, 2006, 06:30:32 PM »

Tom,

This is my basic drawing. Any comments on this?
Mike WU2D

Mike,

The drawing is correct except for rod #1. You do not want any Earth ground connections at the bev input. Instead, connect the secondary cold to the primary cold and to the feedline braid - and let them "float" above earth gnd at that point.  Attach a ground at the shack on the braid and a ground at the terminating resistor - as the only Earth grounds.

This information is according to W8JI who is a well known bev guru.  Do a search on his call and see his website for info on bevs. He has them in 20? or more compass directions.

I have used this config on my bevs here and there are days when the noise floor is S0, with no computer or band noise. The signals coming in from Eu on 75M are strong. When switching to my reference dipole at 60', the band noise is S7-9 and the signals down in the noise at times.  The exception is the high 2el Quad where the noise is down and the signals are strong like the bev.  Bottom line is that you will be able to hear close to a high Yagi if you get that bev performing textbook!

73,
T
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Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
WU2D
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« Reply #5 on: October 24, 2006, 06:51:33 PM »

Would it be better to have a string of magic beads on both ends of the coax to keep common mode noise off the antenna ??

Frank,

Have you been smoking the rope from the other technical discussion?

Tom,

In my case, the Beverage feed is only 20 feet of coax away, just outside and up! Any ground in the shack would be moot. I still think a ground rod just outside the window would be something to try. Heck, I will try it both ways and see what I get for noise.

Mike WU2D
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flintstone mop
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« Reply #6 on: October 24, 2006, 06:52:18 PM »

Halo friends
I have had great success with 600 feet of wire just lying on the ground running here and there through the property. I feed it into the MFJ noise canceller and I can mix that with the inv VEE sig and get rid of hums and buzzes. Sometimes the wire antenna on the ground gives me superior noise free reception for some stations.
Fred
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K1JJ
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« Reply #7 on: October 24, 2006, 07:12:54 PM »

OK, Mike -

Be sure you start the bev far away from the house and clear of towers or metalic structures. If it means a shorter bev and a longer feedline, then do it.

I once had up a SE bev that ran by one of the towers. I could never understand why it didn't perform as well as the other bevs. It was useless in fact.  I later moved it about 100' from the tower, still going in the same direction. I now use it as much as the others. Tremendous difference!   W8JI and others discuss this.

I would STILL float the input transformer and use the station ground at the input end. 20' of coax can still pick up a lot of noise if it exists. My coax run is close to 800' underground to the pair of bevs out in the woods...  Grin  So I need all the help I can get.

T
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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
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« Reply #8 on: October 25, 2006, 12:37:48 AM »

I have 4 bevs here and they are very effective....The unterminated 700+ ft E/W model gets use from 160 to 20 meters...Tom I agree... A properly tuned and terminated beverage antenna hears as well or better than a high Yagi on freqs between 6meg and 500kc
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« Reply #9 on: October 25, 2006, 08:54:44 AM »

No Mike I can't smoke rope for fear to the piss cup
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WU2D
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« Reply #10 on: October 25, 2006, 07:19:17 PM »

No Mike I can't smoke rope for fear to the piss cup

Understood Frank - Then have a beverage.



Tom - Great comments! Lets get this sucker up.. I mean down...

Mike
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« Reply #11 on: October 25, 2006, 08:07:40 PM »

gee Mike good idea but didn't buy any hostraders beer this time so nothing in the fridge.
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WU2D
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« Reply #12 on: November 11, 2006, 03:01:53 PM »

Beverage Progress Report;

Well I got some materials together over the past couple of weeks.
I found some neat black plastic insulators made for electric fencing from Agway - two bags $4.40 for 50 insulators. I bought a box of galv deck screws which fit the insulators. $5.00

Mark WA1QHQ gave me a an old roll of # 20 copperclad - 2000 ft? Freebee  Wink

Last weekend I got my rooftop tripod put back up with new guys and got the Inverted L back online.
I found out how it broke the guys and flew off the roof. It turns out that a rather large and tall tree supporting the end of the inverted L came down in the woods and literally ripped the mast down. It was not simply wind as I had originally thought! Anyway, there was no time to start the Beverage project.

This weekend I had a few hours but have to travel tomorrow. I actually got a lot done. As Tom suggested, I remoted trhe feedline to the beverage rather than starting from the house. I used a garden tool to slit the sod and buried 100 feet of LMR-240 which was the black hard PLENUM rated poly stuff used for factory runs. This should work good underground. Another freebee left over from some project at work. This terminated at my tool shed at the edge of the woods. that will be my feed point.

I unreeled and cut two 278 foot sections of wire. Using a boy scout compass, I made a beeline just 5 degrees south of due west with the first length, starting at the far right of the property (not too far from the shed). I measured 90 feet to the south and repeated the run using the same heading with the second wire.

Again using the compass, I walked 90 feet south from the end of the north wire,but something was wrong. The end of the south wire was in the wrong spot; way to the left (short) according to the compass. I found the problem. The copperclad had a break but the missing 30 feet showed up on the route. It was a clean rusted through bad spot. I fixed the wire and now everything measured right.

I shoved everything overhead and tied it off at both ends -that is as far as I got this weekend. Next comes installing the insulators at hieght and pruning and then figuring out the terminations, grounding, matching and phasing!

Mike WU2D




 


 


* 40MBEV.jpg (24.28 KB, 439x672 - viewed 389 times.)
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WU2D
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« Reply #13 on: November 20, 2006, 09:45:53 PM »

Hi Guys,

Some progress over the weekend. I got the insulators up and cleared the path down both "lanes". I installed the far terminations and the ground rods.

OK - Now how to feed for 40 Meters?

Assuming that I can achieve a wideband match to 75 Ohms on each wire using a transformer - can I simply run two equal lenghs of 75 Ohm coax to a tee at the 50 Ohm coax termnation point from the shack? The idea is that both lines would be "flat" and I would simply take the minor mismatch of 37.5 Ohms to 50 Ohms.

If the 75 Ohm runs are operated as flat lines, it does not matter too much what length they are.

But consider:

The left coax run has to be at least 70 feet to reach the wire from the feedpoint.

It is probably a good idea to make both lengths the same.

And both 75 Ohm runs could use low loss foam RG-6 which has a very high velocity factor (0.Cool and 96 Feet  is actually a full wave at 40M and a half wave at 80M considering the velocity factor.

This would tend to guarantee that 75 Ohms from each leg is presented at the 50 Ohm Tee feed.


Mike WU2D
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« Reply #14 on: November 20, 2006, 10:57:43 PM »

Hi Mike,

Yes, what you propose will work out just FB. Feedline loss is a non-issue with beverages.  As long as you have equal feedline lengths to both bevs, giving the same phase (0 degrees) you are golden.

It ought to be a nice pattern on 40M considering you are running a pair. The front lobe will be narrow... the sides will be clean. Hope you picked out the right state to aim it at...  Grin

Let us know how it goes!

T
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Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
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« Reply #15 on: December 04, 2006, 09:58:15 PM »

Well Guys,

It is on the air! I finally got the Beverage Array completed. As you remember, I wanted a quiet listening antenna with gain to the west with special interest in 40 Meters. That is because I am working the 1929 QSO Party sponsored by the AWA and all participants are West of me and these are weak signals. I used the array over the weekend in the first session of the contest and I can report that is a fantastic performer on both 40M and 80M. It kills noise of course but more importantly on 40M, it rejects shortwave broadcasters from Europe and off the sides. I was hearing stations which were simply being plastered on my inverted L.

By the way, If you are interested in working out west on AM, you have to hear them first and this antenna goes a long way towards putting a coast to coast station together. I did put an amplifier inline to roughly equalize the gain to my inverted L. If your receiver has a preamplifier, this is not required.

The amplifier required a simple tuner up front to eliminate broadcast band cross modulation.

My final design is below - thanks for the ideas Tom. 73's

Mike WU2D


* BEVERAGESCH.jpg (30.22 KB, 648x468 - viewed 327 times.)
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« Reply #16 on: December 04, 2006, 10:31:27 PM »

Hi Mike,

Wow, after looking at the diagram I must say, unbelievable!

That is a first class set up, no JSing around. A pair of phased, terminated beverages optimized for 40M - with a preamp to normalize the gain... outstanding.

I can appreciate how well that antenna works, esp the side rejection since I use the same scaled up setup for 75M in the DX window.

Now you can get in there and start axing for mobiles, guys named John living in Seattle, etc. .. Wink

I wonder if you notice the effects of the narrow beamwidth and sense the drop off into certain areas of the US?

73,
T

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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
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« Reply #17 on: December 05, 2006, 12:26:30 AM »

I think Mike's first diagram is the proper set up.  You want the coupling transformer to have two separate windings, well isolated from each other except for magnetic coupling.  The transmission line should float and not be grounded anywhere near the rx end of the antenna.  The antenna should have its own ground at each end, not to be shared with anything else.

It looks to me like Tom's idea would make the transmission line serve as part of the antenna, since the coax braid would carry the antenna current all the way to the shack ground.

You want to isolate the transmission line from the antenna as completely as possible.  Ideally you would use a physically small, remotely-controlled battery operated receiver with a vhf/uhf link to control the receiver and carry the audio back to the shack.  One end of the  receiver antenna coil would go to ground at the rx end of the antenna, and the other end of the coil would go to the antenna.

When the  receiver is located far from the RX end of the antenna, Mike's diagram is the  closest equivalent to ideal set-up as described above, and that is the way mine is set up.  My shack ground is off to the side of the antenna, about 2/3 the way from the RX end back to the terminated end.

My beverage uses #8 copperweld, 10' high and either 800' or 900' long (I forget which).  The terminating resistor is 488 ohms.  I use 8 nominally 56-ohm 2w carbon composition  resistors in series.  I used to have a single 10-watt carbon composition 500-ohm resistor, but a lightning discharge completely vaporised it, leaving nothing but a sooty residue on the inside of the protective plastic case I had it mounted in.

One of these days I plan to measure the swr on the antenna and adjust the terminating resistor for minimum standing wave, but right now the value of my terminating resistor is an educated guess.

I get much better suppression ratio off the sides of the wire, than receiver end compared to terminated end.

Mine works on 40m, but not so well as it does on 80 and 160.
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« Reply #18 on: December 05, 2006, 01:35:31 AM »

I think Mike's first diagram is the proper set up. You want the coupling transformer to have two separate windings, well isolated from each other except for magnetic coupling. The transmission line should float and not be grounded anywhere near the rx end of the antenna. The antenna should have its own ground at each end, not to be shared with anything else.

Don,

I did some serious reading and found you are correct!

Here's a diagram of the proper set-up for the input transformer feed:
http://www.ok1rr.com/view.php?cisloclanku=2006021801

I've got to go out there and rewire the input balun secondary to a ground rod (with a few radials) - just as Mike needs too.

I think what made me think the other way is reading that the shield needed to float from the shack. I assumed the secondary did too, so tied it to the same point. O'well...

BTW, notice the author talks about having grounds at both ends near "zero ohms" or at least less than 30 ohms each. Think I'll lay out more radials at each end. I had only about 6 short 15'ers at the far end. At 600 ohm termination you'd think that wouldn't be necessary, but what the heck.

Thanks for pointing that out, OM. I'm looking forward to trying my three bevs with the new config tomorrow! They should work even better now - can't wait....

73,
T

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Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
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« Reply #19 on: December 05, 2006, 11:15:41 AM »

[
L.

By the way, If you are interested in working out west on AM, you have to hear them first and this antenna goes a long way towards putting a coast to coast station together. 
Quote


HOW VERY TRUE.....  Nice job Mike,  I hope to work you soon...   Steve
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« Reply #20 on: December 05, 2006, 11:58:50 AM »

Here's a diagram of the proper set-up for the input transformer feed:
http://www.ok1rr.com/view.php?cisloclanku=2006021801

Nice article.  TKS for posting it.

But I am sceptical of the near zero-ohms ground at each end.  That's almost impossible to achieve even with hundreds of radials a half wavelength long or more.

For mine I use a ground rod plus 10-12 radials each about 15' long.  Never  tried to measure gnd resistance; maybe it is <30 ohms.  But if you had the room for an extensive radial system, radial wires under the antenna wire would impair the function of the antenna.  The beverage needs poor soil conductivity to operate properly.  I have seen some diagrams where they used a semi-circular radial pattern at each end, with the radials covering only the half circle facing away from the wire.

Be sceptical of the book on beverages published by W1WCR.  Some of the ideas he presents in his book are bogus, such as the sloping ends of the wire to prevent signal pickup by the vertical drop at each end, and the ground wire laid on the earth surface and extending between the grounding points at each end.  With those two glaring errors, the entire book becomes suspect.  Another questionable idea in his book is the balancing wire parallel to the vertical drop wire at the receiver end, end-fed zepp fashion, used with a midtapped coupling transformer.  The loading effect of a properly terminated antenna will completely unbalance pickup by those two wires.

Much of the info in the book is valid and I find mine to be useful as a whole, but I wouldn't recommend it to a novice beverage builder, who might not be able to filter out the bogus stuff.
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« Reply #21 on: December 07, 2006, 11:10:43 PM »

I will get out there on Saturday and try a couple of more rods and isolation - man I hate this time of year when you can not do much outside after work because of the short days.

Mike WU2D
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« Reply #22 on: December 08, 2006, 11:50:48 AM »

I will get out there on Saturday and try a couple of more rods and isolation - man I hate this time of year when you can not do much outside after work because of the short days.
Mike WU2D

Mike,

I installed the four rods and ground radial systems for the three beverages here  - and also isolated the secondaries.

After two days of listening I hear a definite improvement in the patterns. If I'm listening to a station out west, they are very weak on the SE and NE bevs. Same thing when I listen to a Euro and switch to the other two.  The side rejection is noticably better. The front to back seems about the same - it was always good on them all before.  So, the side lobes seem better.

There must have been some feedline influence, as Don pointed out.  It's well worth the effort to modify them... Wink

73,
T
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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
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