My Beverage antenna is NOISY! Why?

[cottersay]

RadioNut, my antenna building days are over for now; what with the ever increasing Mississippi heat and humidity, and the lovely Poison Sumac that I have had to wade through, I'm done!

 

[NDRADIONUT]

ROGER THAT !

 

[nanZor]

What would contribute to a Beverage being so high in noise over that of a simple dipole (which receives signals quite well in both amplitude and S/N)?

Are you going through an antenna switch which shares a common rf-ground with the other antenna??

If so, try testing the beverage as the *sole* antenna connected, and then again connected to the switch.

Despite having the beverage feedline buried, if connected to the switch, and the dipole coax shield has a lot of common-mode current, you essentially have a beverage connected to a raised-ground!

Ferrites at both the shack, AND at the feedpoint of the 40m dipole may help your beverage get back in shape if common-mode noise is indeed the culprit.

 

[prcguy]

I agree, try a common mode RF choke near the shack where the coax exits the building and another near the antenna feed point. That will help strip off any RF noise conducted from inside the house to the antenna.

The original antenna being only 1.3 wavelengths long and terminated with a resistor probably has a null in line with the end of the wire and a couple of lobes heading off at angles away from where you think it was pointed. Your longer wire should bring the lobes closer in line with the end of the wire but I believe a single long wire antenna, terminated or not will have a null in line with the wire and you have to offset it to place a lobe to land on your target area. Anyone have more info on this?
prcguy

Are you going through an antenna switch which shares a common rf-ground with the other antenna??

If so, try testing the beverage as the *sole* antenna connected, and then again connected to the switch.

Despite having the beverage feedline buried, if connected to the switch, and the dipole coax shield has a lot of common-mode current, you essentially have a beverage connected to a raised-ground!

Ferrites at both the shack, AND at the feedpoint of the 40m dipole may help your beverage get back in shape if common-mode noise is indeed the culprit.

 

[cottersay]

Thanks Hertzian and pcrguy. Great suggestions, and all of which I shall implement. However, I do short both the dipole and the Beverage coax's shield directly to ground through multiple ground rods right outside my shack's window (about 6' from antenna switch to 1st ground rod). I use about five rods for this, but the dipole and Bev coax are both grounded to the same rods. I will test if this is a problem by disconnecting the dipole from the RX/TX auto switch.

Thanks!

-Cottersay

 

[nanZor]

Give it a shot by testing with ONLY the beverage attached with no antenna switch involved.

Just know that ground rods are more for lightning / electrical failures, and aren't really a great RF ground. Since rf doesn't penetrate the earth too deeply, you have at most about 1-2 inches of contact no matter how far you drive in the rod. Ok, maybe 6 inches of contact with 5 rods at least at HF.

Essentially, as far as rf is concerned, you may just have a 6 foot random wire hanging off the back of your rig.

 

[cottersay]

"Essentially, as far as rf is concerned, you may just have a 6 foot random wire hanging off the back of your rig." :-(

At least I added a few radials to the Bev's feed end, but since you can't run radials under a Beverage, I'm out of luck (and will-power) to do much else!

 

[pendulous]

which dx engineering beverage product are using? i have several of the reversible models from them and no issues. while i agree pointing the terminated end right at your house will degrade performance, it should not to the point of rendering the beverage a poor performer relative to your dipole. with the reversible models you need to make sure unused ports are terminated. I recommend a commode mode choke at the feed point end and before running your coax into the shack. try to keep other antennas as far away from the beverage as you can as they will distort the pattern. if you can keep them away, short them to ground when you are using the beverage. Also, you want to avoid having any feed lines running under the beverage. check your connections. i use rg6 with f connectors. believe it or not, if you don't get the f connectors right, the center conductor doesn't make good connection and you will have a problem. lastly, depending on your coax run, the beverages are not efficient antennas, many cases you will need a preamp with at the feed point or at the shack end. I'm talking about the preamp in the radio. it is a separate preamp specifically designed for low noise inefficient receive antennas like a beverage. dx engineering makes the rp1-1, they also make the common mode chokes.

from your pictures, you have quite a bit of space and might consider bogs. dx engineering makes the kd9sv bogs. I have four of them and they work great and only require about 200 feet. They work almost as well as the above ground beverages I have.

 

[cottersay]

Thanks pendulous for the response and the great tips! I have the single wire DX Engineering DXE-BFS-1 Beverage matching transformer (I chose a single wire Bev because I only care about contacts in one direction, which is to the N.E.; which also, of course, allows me access to some European DX). I also bought the high Third Order Intercept DXE-RPA-1 preamp. Oddly, however, I don't seem to need the preamp, as the gain on the Bev is much higher than I thought it would be; my K-1's AGC seems to make up for the normal Beverage losses well enough for me.

I am starting to get pretty darn good performance from my Beverage now, signal-to-noise (and, as I said, gain) wise; it's almost like something is "settling-in". Indeed, I was incredibly P.O.'ed at first that I had put all that work and time and money into the Bev and wasn't getting diddly back, but now I really can't complain! (Well, at least I can't complain now about its performance on 40 meters -- it must work wonders on 80 and 160 meters -- but on 20 meters it is worse than useless S/N-wise, so I stick to my dipole; but I kind of expected that.)

If I had but known a BOG was such a good performer, I would have gone that route! It would have been a heck of a lot easier to "erect", and I wouldn't have had to put up a camouflaged eight-foot high pole in my front yard!

-Cotter

http://forums.radioreference.com/attachment.php?attachmentid=54623&stc=1&d=1458942425

 

[pendulous]

Thanks pendulous for the response and the great tips! I have the single wire DX Engineering DXE-BFS-1 Beverage matching transformer (I chose a single wire Bev because I only care about contacts in one direction, which is to the N.E.; which also, of course, allows me access to some European DX). I also bought the high Third Order Intercept DXE-RPA-1 preamp. Oddly, however, I don't seem to need the preamp, as the gain on the Bev is much higher than I thought it would be; my K-1's AGC seems to make up for the normal Beverage losses well enough for me.

I am starting to get pretty darn good performance from my Beverage now, signal-to-noise (and, as I said, gain) wise; it's almost like something is "settling-in". Indeed, I was incredibly P.O.'ed at first that I had put all that work and time and money into the Bev and wasn't getting diddly back, but now I really can't complain! (Well, at least I can't complain now about its performance on 40 meters -- it must work wonders on 80 and 160 meters -- but on 20 meters it is worse than useless S/N-wise, so I stick to my dipole; but I kind of expected that.)

If I had but known a BOG was such a good performer, I would have gone that route! It would have been a heck of a lot easier to "erect", and I wouldn't have had to put up a camouflaged eight-foot high pole in my front yard!



-Cotter

http://forums.radioreference.com/attachment.php?attachmentid=54623&stc=1&d=1458942425

Cotter, glad it is starting to perform better. That almost sounds to me like a noise source has gone away the other thing I have heard of, never experienced myself, is the ground quality changing. the beverage as you know depends on ground and believe it or not, you don't want soil with good conductivity. So if it was really wet and started to dry out, that would definitely impact your pattern. One trick that Victor Misek (he authored a few outstanding books on beverages) has suggested to deal with ground irregularities is to run an insulated wire from your ground rod at the terminated in and connect it to the ground rod at the feed point end. this helps to stabilize the ground. I have not tried it on a standard beverage but I have done it on a steerable beverage with good success. in fact, my main BCB AM dxing receive antenna is a misek steerable beverage and it works great using this grounding method. You need to use a phasor with it but I can null or peak stations in the AM band in some cases by 30 to 40 db. these antenna is only 200 feet. The misek antenna is pretty amazing. good luck with your new beverage. if you ever get interested in trying a bog, dx engineering carries the kd9sv single and reversible beverages and they are so easy to install its silly. you can use zip cord, speaker wire. They recommend and i use the type 2a military telephone wire and it is cheap and works great.
sorry for going on and on but the last three years I have experimenting with many different low band antennas. Another one that is super easy and works very well, but requires support is the pennant.

 

[cottersay]

Thanks again pendulous; so many fascinating antennas, and so little time!

-Cotter

 

[nanZor]

One other thought with the long feedline despite being buried - is it physically or "galvanically" isolated, ie a 1:1 with no common connections?

I don't know how the dx-engineering units are configured, but wonder if a 1:1 isolation transformer would be recommended. I'm sure ON4UN would have approved.

 

[cottersay]

Hertzian, the DX Engineering Bev transformer has an isolated winding, so I think I'm good to go there.