Beverage Questions

[w9jsw]

I have a portion of my farm that has electric fence on it. I decided to try it out as a beverage to see how better it would work before I install a proper beverage. It runs from the feed point south for 200ft then east for 800ft. Feed end got a 75 ohm to 450 ohm transformer with a grounding rod. Other end is a  500 ohm comp resistor (5 - 100ohm in series) and a ground rod. Good enough.

It works! On 80M, I see a drop of 2 S units on signals and a drop of 5 S units on noise, so much more usable signal to noise.

Strangeness on 160M. I have a BC filter in the feedline back to the SDR receiver. Has a cut-off of around 1.6MHz. Spectrum on 160 before would see overload as I increased the LNA gain to the higher end. A line every 10 khz. I don't see that now, but I see a local BC station (940khz) showing up at 1.880MHz (second harmonic)  in perfect fidelity. Around S6. Even if I set the LNA to -12db it will not go away.  Going back to the Inverted L I see no signal at all but noise is at S6.

Thoughts?

John

[w8khk]

I have a portion of my farm that has electric fence on it. I decided to try it out as a beverage to see how better it would work before I install a proper beverage.

I see a local BC station (940khz) showing up at 1.880MHz (second harmonic)  in perfect fidelity. Around S6. Even if I set the LNA to -12db it will not go away.  Going back to the Inverted L I see no signal at all but noise is at S6.

Thoughts?

John

Is the electric fence wire a contiguous run, or are there splices in it?  Perhaps some rectification occurring at a junction of two wire sections, causing  frequency doubling to occur at one or more points in the wire run?  I am sure you disconnected the fence power supply if you are using the fence as a receiving antenna!

You might also try a series L-C trap in parallel at the antenna side of the balun to block the 940 kHz fundamental, but if the cause of the 1,880 kHz signal is rectification, that may not help.  An alternative might be a parallel-resonant circuit in series with the beverage, such that fundamental 940 kHz signal current is reduced, perhaps eliminating the doubling that may be occurring at a joint.

There is also the possibility that some other antenna, or structure, might have a joint that is rectifying, and re-radiating the second harmonic, now being heard in your beverage, which might not be the cause of the problem at all.  Have a look at this:
  http://amfone.net/Amforum/index.php?topic=26690.0

I would expect a proper beverage, constructed with new wire, proper insulation, and solid joints might not exhibit this problem.

We should ALL be fortunate enough to have the acreage necessary to implement a beverage or a rhombic.  Too late in life for me to try to move, I would never get around to completing all the projects I have started.

[w9jsw]

Yes I disconnected the fencer. It puts out 14kV and that would toast my little Hermes-Lite 2 for sure.

I separated that section completely from the rest of the fence. It is all shut off now as we only have 3 old retired horses that only try to break into the barn to be fed, instead of trying to break out of the pasture to be free. Old horses are so nice.

The current test wire for the beverage certainly has some joints. As is common, there are compression sleeves that join the sections together. Not that many, but a few. Guess it only takes one. There is also a tensioner that is in the circuit. I will take a handful of clip leads out there and bypass every joint to see if that helps. Even if it does not, the beverage has improved my RX capability quite a bit on 80 and 160 which was the intent. Now on to the proper install.

On edit - it was the tensioner acting as a rectifier.

[DMOD]

RE Beverages and Electric Fences.

After I put my Beverage up I had this periodical "tick" on all bands.

Thinking it was a power line arc due to dust or whatever, I took my Yagi and 2m receiver and walked about 5 miles around the burb trying to track it down. No luck.

I walked out on the deck and oriented it vertically and did a 360 sweep. Ahh, coming from 280 degrees.

I took the truck and went in that direction stopping occasionally and the signal kept getting stronger. It was max at a cattle farm 2 miles just outside my burb.

I talked to the farmer and told him about my crazy hobby and told him I suspected his cattle fence. He said, "Heck, I got time let's walk around the pasture."  At one corner we found a tall Fescue stalk discharging the electric fence periodically. Pulled that sucker up and that was it. Later that summer, I brought he and his wife some Bryer's Ice cream.

Nice guy and friendly cattle as they followed us around like puppies.

[w9jsw]

Here is the plan

[Steve - K4HX]

Nice! That setup is not bidirectional. It's unidirectional, switchable in two directions. 

When you set it up, use a potentiometer for the load and adjust for the least amount of variation in SWR or load impedance across the band(s). Do not set the pot for the best SWR at any one freq. In fact don't worry about the actually SWR unless it's way off. Concentrate on minimizing variation across freq. This will yield the best directivity.

[kb3ouk]

RE Beverages and Electric Fences.

After I put my Beverage up I had this periodical "tick" on all bands.

Thinking it was a power line arc due to dust or whatever, I took my Yagi and 2m receiver and walked about 5 miles around the burb trying to track it down. No luck.

I walked out on the deck and oriented it vertically and did a 360 sweep. Ahh, coming from 280 degrees.

I took the truck and went in that direction stopping occasionally and the signal kept getting stronger. It was max at a cattle farm 2 miles just outside my burb.

I talked to the farmer and told him about my crazy hobby and told him I suspected his cattle fence. He said, "Heck, I got time let's walk around the pasture."  At one corner we found a tall Fescue stalk discharging the electric fence periodically. Pulled that sucker up and that was it. Later that summer, I brought he and his wife some Bryer's Ice cream.

Nice guy and friendly cattle as they followed us around like puppies.

Electric fences and antennas can coexist if you keep them nice and clean. One leg of my 75 meter dipole runs over top of the fence for my wife's sheep. I hear nothing on HF. I have a modern solid state fencer on it, the older ones were noisy even on a clean fence. I try to mow under the fence at least twice a year. I have a 2nd wire laying on the ground that runs parallel to the fence for about half of its 500ish foot length that i use for AM BC listening and it is quiet too.

[KL7OF]

Electric fencing wire works ok for beverages..iused it and it lasts about 4years before it starts to give trouble..rust..breaks..connection corroding.. eastern wa and alaska...14ga thhn or better yet copper clad steel..gud luk. I

[w9jsw]

The roll of 17ga fence wire costs $25 bucks for a 1/4 mile of wire. The current one that is being used for testing was installed in 2008 and is still conducting. This is a price performer and will work fine for a long time.