East-West Reversible Beverage

One slow step at a time my Beverage receive antenna plan is steadily progressing. As of this week I have 3 of the planned 4 reversible Beverages in operation. The latest is the east-west Beverage, and the existing ones built in 2020 are the northeast-southwest Beverage and the north-south Beverage. 

Like the NE-SW Beverage the new antenna is a 2-wire electrically reversible design. As I watch the weather batter the N-S coax (RG6) Beverage I am increasingly of the opinion that an open-wire Beverage is more reliable and easier to maintain. Coax requires substantially more mechanical support since it cannot take much tension. It droops and is more susceptible to wind, ice and falling tree limbs. Although it continues to work well I can see that a day will come when it will have to be replaced.

Regular readers may recall that this most recent Beverage project began months ago. First the area had to be surveyed to find the best location. Next came the clearing of the bush. That turned into a frustrating exercise because I didn't mark one of the termination points (big tree) and I cut the wrong path. Correcting that error wasn't difficult because the chosen route has relatively few trees and bushes that had to be removed.

At right is some of the cut brush alongside the (still frozen) swamp at the east end of the antenna. There are smaller piles of cuttings all along the route. These several acres of bush have no use so I can leave it there to decay naturally.

Antenna specifications

The Beverage is 156 meters long. I measured it to be certain rather than estimating from the dimensions of the property. The west end is in the tree line about midway along the north-south Beverage. The east end is just inside the swamp that I share with several neighbours. 

I could have made the Beverage longer by venturing into the swamp. The first meters of the swamp are frozen in winter but range from damp to standing water at other times. Maintenance would be so unpleasant that I ventured no further east. The performance benefit of another 20 meters (to make it 175 meters) isn't worth wading through the muck.

Since the NE-SW Beverage works so well I made this one the same. The wire is AWG 17 aluminum electric fence wire vertically spaced 4" (10 cm). Height is a pretty consistent 2.5 meter, and slopes downward starting 10 meters from the eastern termination. With snowmobiles, hunters and deer becoming more common I don't dare place the Beverage any lower. I warn my neighbours what's hiding in the bush when I allow them access. The aluminum wire can be difficult to spot if you don't pay close attention.

Supports

Most of the selected path is open ground or with trees too small or not in positions to act as supports. This makes the antenna route easier to use and maintain but requires construction of supports. I used standard ¾" PVC pipes spaced no more than 20 meters apart. Rebar and other scrap length of ~½" metal rods peg the pipes to the ground. Since they tend to sink into the soft ground I later added small preserved wood platforms, pierced to pass the peg.

The picture below shows the variety of supports used for the Beverage.

The first picture (left) show the westernmost 40 meters of the antenna with the tree anchor and two of the PVC pipes. PVC pipe is not strong, but it doesn't need to be. The load is primarily carried by wire tension, with the pipe experiencing very little vertical and lateral force, even in a strong wind. In a way it's the wire that's holding up the pipes! Wood or metal posts with insulators are alternatives. 

Slits sawed into the pipe hold the antenna wire and wire ties hold them there. An advantage of PVC pipes is that they can be easily extended by inserting a short length of the same pipe in the coupling flare at one end (third from left).

Yes, Beverages can cross without coupling. The resistance loss (inefficiency) lowers the mutual coupling to a very low value. In the crossing picture (second from left) the NE-SW and E-W 2-wire Beverages are only 6" apart. The E-W Beverage crosses the N-S Beverage at the west anchor point, as we'll see later.

For the several trees used as supports I used PVC and electric fence screw-in insulators, shown fourth and fifth from the left, respectively. Between supports PVC spreaders (on the right) help to maintain a consistent wire separation of 4" (10 cm). They are made by quartering a 5" length of PVC pipe, cutting ½" slots for the wires and drilling holes for wire ties.

The crossing of the N-S coax Beverage is at the west termination. This is perfectly fine. What you must avoid is terminations at the same location because the proximity of the grounds will degrade the patterns of both antennas. The left picture shows plastic egg insulators, dacron rope and nails on the tree as cleats to support and tension the wires.

A spreader was added at the insulators to keep the wires in position as they are pulled downward to the head end electronics. Two screw insulators on the tree and another spreader ensure the wires touch nothing along the way, including each other. A cable tie holds the box to a length of pressure treated lumber at a height that will keep it out of the snow most of the time. The board is nailed to the tree.

After several trials a gap in the subsurface stone, rock and tree roots was found to pound in the 4' copper plated ground rod. All the Beverage grounds have now been upgraded to that shown on the right. The black AWG 18 wire has a spade lug to connect to the box. On the ground rod end a thin copper plate is drilled and soldered to the wire. A stainless hose clamp bends and holds the plate to for a high surface area copper on copper bond.

Reversing electronics

The head end electronics is identical to that of the other 2-wire Beverage. The only difference is its cleaner layout using a larger prototype PCB. Compare the two below.

I labelled the SPDT reed relays and whether each is normally on (NC) and off (NO). I made west the default direction that, because of my contest activity, west will be used more often than east. The relays are powered by +12 VDC on the coax -- RF and DC are separated by capacitors and RF choke -- to reverse the direction. The unused direction is terminated to a 75 Ω load to prevent reflections that would destroy the unidirectional pattern.

A 7:3 transformer uses the 2 wires in common mode for the east direction. It is fed via the centre tap of the primary winding of the 12:4 balanced transformer. The 12:4 transformer receives the differential mode of the antenna wires for the west direction. A reflection transformer (not shown) at the east termination converts the common mode coming from the west into a differential mode signal, using the antenna wires as an open wire transmission line. More detail can be found in the article on the NE-SW Beverage.

Feed line

I purchased a 152 meter (500') roll of inexpensive RG6 plenum coax, about half of which was used to connect the new Beverage to the remote antenna switch. It is simply lying on the ground. There are several issues I had to deal with for such a long run of coax:

• Animal damage, primarily deer, rodents and (yes) humans
  
• Interactions with the N-S Beverage
• Ease of installation and maintenance
  

I have enough unused bush that there are route choices. A friend help me cut a narrow path through the vegetation. On bare ground the coax was placed alongside rocks and trees. Trampling by deer, snowmobiles and other other vehicles is thus avoided. There is no good protection against rodents other than gel-filled cable which is expensive and usually unnecessary. I have had no trouble with rodent damage with cables on the ground, and that is the experience of many hams. Since it can happen I prefer cheap coax that I don't mind replacing should damage occur. Black jacketed cable is recommended since its tends to be more resistant to the elements regardless of its specifications.

I routing the coax out from under the N-S Beverage as soon as practical (less than 10 meters along) and kept it 5 to 10 meters distant, running roughly parallel on the east (bush) side. At the south end the coax turns west, where it lies close to the coax from the N-S antenna for 10 meters on the way to the remote switch. Initial listening tests indicate little or no discernible pattern degradation of the N-S Beverage in both directions. I am prepared to insert chokes along the coax should interaction become apparent.

There are a couple of places where the coax crosses openings in the tree line where I need to walk and vehicles may cross. I will bury those several inches below grade as I did for the other Beverages.

There is no picture to show the coax in the bush since it is really difficult to get one that isn't fuzzy or confusing. Bush photography is difficult and I am no good at it.

Debugging: direction selection and one dead direction

The new Beverage plugs into a port on my remote Beverage switch. No other work needed to be done to make it available for use at the operating desk. Or so I thought.

When I turned the rotary switch to the reserved position for the new Beverage all I heard was silence. As I've learned over the years the best approach to a difficulty of this type is to sit and think for a few minutes to review all the steps of the construction and testing. 

Suspecting something simple I opened my home brew antenna selector and traced the wires. I discovered that I had not connected the third or fourth ports to the rotary switch. A few seconds with a soldering gun and atmospheric noise was heard from the receiver. 

In both directions the signal level was comparable to the other Beverages. That was reassuring. A quick check on 30 meters (the lowest band open at the time) confirmed that it was reversing correctly and that it had directivity in both directions.

A test with an antenna analyzer showed that it was switching and that the SWR was reasonable though a little high in the west direction. I won't reproduce the SWR scans since they are very similar to those of the other 2-wire reversible Beverage, linked to earlier in the article.

After sunset I gave it a try on 160 meters. The first station copied was C92RU in Mozambique. Their signal was copied well with the new east Beverage and not with the adjacent south and northeast Beverage directions. C9 is due east so this was a promising result. Two evenings later I was pleased to work them.

Unfortunately the west direction didn't work so well. Unlike earlier in the day there was silence. A check with the antenna analyzer confirmed that it was not working in its default direction but all was good in the reverse (east) direction.

The next day I made the 250 meter trek to the head end to see what was amiss. I suspected a loose wire at the head end or the reflection transformer at the east end of the Beverage. There was no obvious fault so I removed the reflection transformer for testing. It took some time until I discovered an intermittent short between the windings. 

I replaced the outer winding, successfully tested it and put it back in the box. We have a few days of rain forecast so there may be a delay taking it back out to the swamp. I saw no reason to delay this article, so I am ending on this hopeful note.

Next steps

The new Beverage direction selector is a work in progress that has been slowed by too many other projects. I continue to use a rotary switch to select the Beverage and a toggle switch to reverse direction. It's awkward but I won't be using it very much over the summer months. Work on the new selector will have to be squeezed in on rainy summer evenings so that it's ready in the fall.

It's a shame that the new Beverage is ready just as the winter top band season is ending. It would have come in handy to more reliably copy the recent A25RU DXpedition. They copied me better than I copied them since I had no receive antenna pointed their way. 

Next month is the annual rolling up the radials ritual for my big vertical. Until early fall I must use a relatively poor base loaded 160 meter vertical. If all goes well my 160 meter station will be significantly improved for the 2021-2022 top band season. In addition to the extra two Beverage directions I have a plan to improve my transmit antenna efficiency.

The last Beverage in my 8-direction receive array is for NW-SE. It is last because from here these are the least useful directions. Because of that and the problem of finding a good route for it in the bush I am contemplating alternatives. One possibility among several candidates is a reversible end fire array using small verticals.

This is the last of my winter antenna projects. Over the warmer months my attention turns to the towers to build 10 and 40 meter antennas and to relocate a few antennas to more permanent locations. I've been moving antennas quite a lot since moving here in 2016 as towers were raised and mediocre antennas were supplanted by better ones. Work on the antenna farm never ends, and that's how I like it.