Beverage Question

[K1JJ]

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

I would model it to see just what pattern it wud produce, Jack. I would expect it to be degraded to some degree, not exactly what you desire, depending on the exact layout of the wire.

An alternative might be to aim it in the best straight line you can, averaging between NE and east. The shorter the Bev, the broader the frontal lobe.

Also, consider a pair of phased shorter Bevs spaced as wide as possible (up to .6 wavelengths apart) aimed properly and straight.  A pair of 200'ers will have a similar parttern as the single 400'er, but a better side rejection. Well worth the effort.

BTW, be sure to keep it clear of and not beaming into noisey towers that can kill your S/N ratio cuz of snaps and pops, etc.

Maybe others have some ideas too.


T

[KM1H]

Use some brass Slinkys for loading, stretch 5-6 over the 200'. It takes around a 1200 Ohm termination which you can experiment with for best rearward null. Been there done that, works well even on 160.

Carl

[KL7OF]

Use some brass Slinkys for loading, stretch 5-6 over the 200'. It takes around a 1200 Ohm termination which you can experiment with for best rearward null. Been there done that, works well even on 160.

Carl

Where do you get brass slinkys?   

[K1JJ]

Here's JI's info on a Slinky / loaded beverage - also an antenna model of one:


http://www.w8ji.com/slinky_and_loaded_beverages.htm


It's interesting that if we go too far and overload it, the Bev reverses direction.

T

[k4kyv]

To-night I worked a 100-watt station in Washington state on 3885.  I was able to copy him better on my beverage than on the transmit antenna, even though WA would be well off to the side of the antenna, but probably out of the null.  I haven't looked at the map to see exactly what his direction is from here.  No line noise bothering the beverage at present.

When the electrical noise is quiet, I often get a better s/n ratio with the beverage regardless of  direction.  It seems to become more directional when I deploy the full length.  Right now, it is about 390' long, and elevated to 10'. I wish I could lower it to 3-4', but that would put an obstacle between the house and the back garden area. I have never found even the full 800-900' length (I forget which it is) to be tremendously directional, but it seems to pull distant weak signals right out of the background hiss when the band is quiet.

I guestimated, and put in a 500-ohm terminating resistor, which theoretically should be close to the surge impedance of the wire, #8  copperweld at 10', but I am aware that the impedance can vary due to soil conditions, and may change with seasons and rain/drought conditions.

There is some kind of a resistor (I forget the name for it) that is actually a solid state device that changes resistance with applied voltage.  You can use the antenna wire to carry the DC if the voltage source is properly isolated from rf, and vary the voltage (thus changing the terminating resistance) from the shack for the best f/b ratio when trying to receive a given station.  I believe W8JI may have some information about this on his website.

I have already had one terminating resistor to completely vaporise from a lightning pulse.  No trace of the resistor, which was a 10 watt carbon composition resistor, in the enclosure except for the wire  leads.  I replaced it with several 2-watt composition resistors in series to bring the total up to 500 ohms.

I mounted my matching transformer inside the bakelite base of a defunct 807 tube, and wired in a 5-prong tube socket so that I can plug it in and unplug it. I try to always unplug it when there is a T-storm threat. I have it mounted inside a metal rural mail box which is attached to a couple of concrete blocks to keep wind from blowing it away.  I just pull the coil and leave it lying inside the mail box so I can easily get my hands on it to plug it back in after the storm threat. I once had to rewind the transformer after a lightning jolt crapped it out.  It seemed to work OK rewinding it on the old toroidal core.

[KM1H]

I started using the Slinky around 25 years ago and when it started to perform well I discussed it on 160 SSB with several of the serious DXers and on the Topband reflector a decade later where JI picked up on it.

My procedure was purely cut and try as I didnt have access to portable test euipment or software, they didnt exist in 1985.

What I did find is that 5 large Slinkys stretched over 150-180' equalled a 500' wire Beverage mounted parallel and about 400' away. At the time I was using steel Slinkys and they rusted away in under 2 years so maintenance was a pita. Suprisingly the performance was still good until they broke so I surmise that the RF signal kept going deeper into virgin steel for its path. I bought a dozen brass ones from the guy selling the antennas on Fleabay about 2 years ago.

Where I believe JI has it wrong is that the lumped coil loaded Beverage does not work well due to the distortion of the wavefront and Vp. OTOH the continuously loaded helice of the Slinky is equal over its full length. I use local BCB stations in the 1300-1600 KHz range for termination adjustment using a 2K carbon pot and then to fixed carbon resistors.

Carl

[Steve - WB3HUZ]

EZNEC may not be accurate as for as gain, but the shape of the pattern should be OK.

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.

[Steve - WB3HUZ]

Bending it would not be good. If you only have 200 feet, you can still put up a very good array for 80 and 40 and it can work pretty well on 160. Put two side-by-side (maybe 15-20 feet spacing), but offset (one shifted forward of the other) by about 30-40 feet and end-fire phase them. If done correctly, you'll have a system that will work about as well as a 400-500 foot long single wire.

You'll likely hear like you've never heard before.

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

[WA1GFZ]

During the summer I had a 175 foot beverage set up at the other qth with a KAZ both facing west. I would say the KAZ beat the short beverage 95% of the time using WWV and WWVH as test signals. The null off the back of the KAZ faced WBZ and pulled it low enough to hear other stations. The olny time the short beverage shined was N.Y. AM stations. I was going down a hill facing west. The base of the KAZ was only 30 feet so it didn't take much yard space and only 15 feet high. Once the leaves come down I plan to put up a pair of phased KAZ loops. I suspect a pair of beverages would work a lot better than a single if you can fit them in your yard. I tried 500 ohms and 1000 ohms as loads for both.