(Compiled from inquiries I made to the TopBand Reflector and private communications)

Two Wire Beverages:

I use 2 wire beverages with good success. Mine are 580', 12" spacing, and average about 8' or 9' off the ground.I always wound my own transformers. This year, I tried the K1FZ matching and termination transformers. I don't know why, but they perform much better than my own units. I would advise using a termination transformer on the distant end. . . it will help you get optimum front/back. The spacing is not real critical. If it varies somewhat, it's no big deal. Good luck and 73. . . Dave W0FLS >1)Use an end termination transformer (wind my own) or just ground/float the >far end? I recommend the termination transformer because you will get better F/B if it's done correctly. Simply grounding one wire will work but not as well. >2)Okay to let the spacing vary a bit (6 - 12 inches) with the tree trunk >diameters? Yes, some variation is OK but try to keep the variation gradual over distance. Sharp changes create impedance "bumps" which are not so good. >And any other comments/advice would also be warmly received ;-) Be sure that the unused feed is always terminated (dummy resistor, etc.). The power in that feed has to be dumped somewhere or else it ends up going back down the Beverage and into the other feed as an unwanted signal. Also, it's a good idea to measure the SWR with an antenna analyzer (MFJ259 or whatever) and trim the impedance matching transformers for lowest SWR. 73, John W1FV > 1)Use an end termination transformer (wind my own) or just ground/float > the far end? By all means, use the reflection transformer! Establish a good ground at both ends with ground rods or equivilent. I like 1-inch copper pipe, since every copper-plated ground rod I've ever installed has rusted through the ccopper in short order. You can wind your own transformer: it's a simple process. > 2)Okay to let the spacing vary a bit (6 - 12 inches) with the tree trunk > diameters?Yes, but try to keep the run in a straight line. If you are going to use trees to support the wire, consider nailing or screwing crosspieces made from 2x2 lumber (15-18-inches wide) at constant heights from the round, and with notches at the top to retain the wire. You can space them 12" - 15" for 160, and the wire can be pulled tight when resting unrestrained in the notches. We've never used trees as supports: we fabricate "Beverage Poles" out of 2x2 poles, with a 15-inch crospiece at the top (with notches). I use an auger bit to dig 2-inch holes 18-inches deep in the yard, and support the poles in these holes. My Bevs come down in the Spring, and when we were doing the W8LT 160M Contest efforts, we had a large open field to navigate for our long Bevs: no trees to use! 73, Jeff Maass

Using Ladder Line for the Beverage Wire:

I've heard it mentioned a couple of times by guys on the reflector and ON4UN briefly alludes to constructing a 2 wire Beverage using 450 ohm transmission line (pp 7-22 and 7-23 of his book). I thought this might make installation a lot easier if I could scrounge up the wire. If there is a technical down side to using such closely spaced conductors, I'd appreciate hearing from any knowledgable folks. Ladder line works fine. The only disadvantages are cost and wind loading. However, two parallel number sixteen copperweld wires cost about 5 cents per foot of antenna. Now figure out how you would make spacers, and how long it would take to install the antenna using each system! You could also use 300 TV twinlead. I've used 450 ohm line for all my two wire Beverages since the early 70's. For me, the extra cost is offset by the ease of construction. There are no electrical disadvantages when using close spaced wires, other than some slight deterioration of termination in wet weather with plastic "ladder line". As a matter of fact, I don't believe there are any real advantages to using modest or wide spaced conductors in two-wire Beverages. As a general rule, the closer and more evenly the wires are spaced the better the antenna behaves. That's because it is easier to keep the standing waves off the line, making termination better over a wider frequency range. Think of the wire as serving two functions, as an antenna with the wires tied in parallel and as a transmission line to reach the far end. Anyone who understands transmission lines would never use a very long, wide-spaced, line (more than a few thousandths of a wavelength spacing) because they know it would be a very poor transmission line. The longer the line the more critical the spacing is. 73, Tom W8JI I wrote an article in the early 80's describing how to use coax, twin lead, or any other transmission line to make a Reflection Beverage. I had a similar article in Communications Quarterly. The point of both was you could use almost any transmission line if impedances of transformers were adjusted. Certainly that would apply to coax, although you would have to be careful about voltage distribution at each end. I have used 300 ohm twinlead and 450 ohm ladder line with equally good results, and coax wouldn't be a problem either. On 160 meters (or anywhere below UHF) virtually all transmission line losses are related only to conductor resistance...not the dielectric. Keeping that in mind, any thin small conductor could be both electrical and mechanical problems. 73, Tom W8JI Since a beverage antenna is carrying no current, ohmic losses aren't really a factor. You could use #30 wire if you could ever get it to stay up! Anyway, 18 gauge should be fine. However, if it's soft copper it will stretch and may break under weight of ice and snow (particularly when combined with wind). Copperweld would be a much better choice (mechanically speaking). I use #18 military surplus telephone wire (steel) which I buy in one mile spools from Fair Radio Sales of Lima, Ohio. It's made to be stretched and really holds up well to the Iowa winters. It comes as a pair of wires so I have to pull them apart which is kind of a pain. . . but it's good wire and the price is right. 73. . . Dave W0FLS I am using two wire bevs made from 450 ohm PVC covered ladder line. Here's what I know about it: 1) It is convenient to run out - more so than with normal two runs of say #`14 THHN stranded at say 2-3 foot spacing. 2) I am told it is SLIGHTLY less efficient than a two wire at 2-3 foot spacing 3) It's use requires a feedpoint matching xfmr with its output impedance made for 450 ohm ladder line RATHER than the 600-800 required for the two #14 wire variety. 4) Similarly, the reflection xfmr required at the far end must also be customized for 450 ohms as well. I have two such bevs made from 450 ohm ladder line I purchased at RADIOWARE (Craig Clark at 1 800 950-WARE) The CUSTOM feedpoint and REFLECTION xfmrs I had made for me by Clark Electronics (K1FZ). These cost $129 and $99 respectively - you can reach Bruce K1FZ at
[email protected] Good luck 73 JEFF I have 4 beverages constructed with the 450 ohm ladder line, and they work just fine. I have also made one out of RG-58 coax, which also works just fine. Remember, on a single wire beverage, that there are two signals present at all times. One from the front direction, and the other from the rear. You could run a coax feed to both ends, and have a bi-directional antenna, just by hooking one or the other to your transceiver. or you could use 450 ohm ladder line to send the far end signal to the near end. Thus, between either conductor of the 450 ohm ladder line to ground, you have one signal, and between the two conductors, is the other signal. This allows you have both near and far signals at one end, at the same time. Proper transformers (2) at the near end and a single 1:1 transformer at the far end should do the trick. I have several twists in the ladder line, every few feet, as this makes it less susepticle to the wind. The two wire beverage has two modes, first the antennas mode (same as a single wire beverage, both wires have front and back signals present), and secondly, the transmission line mode (the two wires in the ladder line carry the far end signal to the near end). Any trnasmission line can be used for a beverage, 50 ohm coax, 90 ohm coax, 300 ohm TV twin-lead, 450 ohm ladder line, 600 ohm ladder line, or a pair of open wires of any spacing. The only difference is the matching transformer requirements. Hope I have helped you understand what I am trying to get across. 73 & DX, Dick - N6FF >In my limited understanding of >terminating the far end - I though a transformer was necessary when the >characteristic antenna impedance differed from 450 ohms. ] A transformer is ALWAYS necessary. >ON4UN gives the impedance of a 2m high ladder line Beverage at 424 >and 449 ohms respectively using 450 and 300 ohm ladder line >Wouldn't it then be possible to dispense with the > transformer at the far end and use a simple open/short circuit termination? Nope, won;t work for crap. That ground one wire idea makes no electrical sense at all. 73, Tom W8JI A procedure I use for "tweaking" the reflection transformer is to adjust the turns ratio until the SWR in the reverse direction at the receiver end is flattest. By flattest I mean that SWR exhibits the smallest variations up and down over a wide range of frequencies, and not necessarily the lowest SWR. With an antenna analyzer like the AEA or MFJ, sweep the frequency from 1.8 to as high as 10 MHz and look for the SWR to change the least over this entire range, not just inside the amateur bands. This procedure usually gets you very close to the optimum. 73, John W1FV I've been involved in re-doing the low band antennas at KC1XX the last few months in preparation for the upcoming contest season. I helped install four 2-wire Beverages which use the K1FZ KB-2 feed box. The 160, 80, and 40 meter stations will be using the Beverages. I have to agree the performance and construction quality of Bruce's boxes are excellent. Also, Bruce has been very good about providing "tech support" for his products. For those of you doing 2-wire Beverages, he also now has a reflection transformer product, the KB-3. In general reflection transformers will give you much better F/B than simply tying one of the wires directly to ground, which is what most people do. At KC1XX we saw a big improvement in performance when we changed over to reflection transformer terminations (our own homebrew units) for all the Beverages. BTW, I have no commercial interest or affiliation with K1FZ. 73, John W1FV
N1EU Postscript
I've installed a pair of two wire Beverages using 450 ohm 18AWG copper-clad ladder 
line and they work fine.  However, significant improvements have been made over the 
last 3 years as a result of changes to the reflection and matching transformers.
The first transfomers followed the designs I found in several of the popular
books.  The new transformer followed the design presented by W8JI in 
Communications Quarterly, Spring 1997.  Signal level, f/b ratio and SWR 
all improved. More information on the transformers I wound can be found here.

Adding Surge Suppression to a Beverage:

I would appreciate any suggestions on adding surge suppression to the terminating end of a single wire Beverage. I have a small 12vdc relay powered down the wire that I use to switch between uni/bi-directional, and routinely blow its coil. I've also seen my multi-watt carbon terminating resistors vaporize. W4BUW: CONSIDER PUTTING A BLOCKING DIODE IN PARALLEL WITH THE COIL TO SHORT THE BACK EMF WHEN DE-ENERGIZED. THE DIODE CAN BE ANYTHING FROM A 1N4001 TO A 1N4005, THE HIGHER THE PIV, THE BETTER CONSIDER ADDING A NEON BULB, SOMETHING LIKE A NE-2, FROM THE ANTENNA SIDE OF THE TERMINATING RESISTOR, TO GROUND. WHEN EXCESSIVE VOLTAGE APPEARS, IT WILL CAUSE THE NEON BULB TO FIRE, AND HOPEFULLY SAVE THE TERMINATING RESISTOR. I THINK THE NEON BULB WILL ALSO SAVE YOUR RESISTOR, AS IT SHOULD FIRE WELL BELOW THE RATING OF THE RESISTOR. A 450 OHM RESISTOR, 2 WATTS, SHOULD HANDLE ABOUT 60 MA. AND IT WILL TAKE ABOUT 30 VOLTS TO DEVELOP THAT MAGNITUDE OF CURRENT. PICK A NEON THAT WILL FIRE (CONDUCT) AT SOMETHING LESS THAN THIS VOLTAGE, AND YOU SHOULD BE ABLE TO SHUNT THE DESTRUCTIVE CURRENT TO GROUND BEFORE IT EXCEEDS THE RATING OF THE RESISTOR. AN MOV AT LESS THAN 30V SHOULD DO THE SAME THING. N0TT: if you use back to back series-connected zeners across the relay coil, that would work better I think and offer more protection, with less likelyhood of burning out the diodes. 4X4NJ: I used to have the problem of "evaporating" matching transformers and resistors. About 5 years ago, I addopted a very simple cure for this, and so far, no more "evaporating" parts due to lightning surges. My matching and termination components are contained in small plastic weather proof boxes, and I simply bypass the antenna side of the transformer or resistor to the ground side through a spark gap. The spark gap consists of heavy solid wires - about 10 AWG, soldered to teardrop terminals that are placed under the screws going to the antenna and ground. The ends of the wires are cut with "side cutters" leaving a nice "knife edge", and I position the two edges very close to each other. A piece of paper makes a nice "feeler gage" for this purpose. It is very effective, most simple, and negligible cost. W8JI: You might bypass the relay coil with a .1 uF 50 volt capacitor in parallel with a low voltage MOV. Choke each of the leads leaving the coil with a single layer choke of about 100 uH. Be sure you tie one terminal of the coil directly to the relays metal frame or pole- piece if you can. Are the resistors "real" carbon composition resistors or are they carbon film? Virtually all carbon resistors are now carbon film, which have very poor immunity to surges. Metal or carbon film resistors will fail constantly no matter what wattage you use. Also, be sure to use close spaced spark-gaps at the antenna ends! I just use a post-type insulator nailed to a tree or post. I loop the wire around two ribs, and then secure it. I form a gap from loose wire ends. K0HA: While Ohmite's OY series of ceramic composition resistors ("ideal for circuitry associated with surges, high peak power or high energy") have done a good job for me by themselves, my recent installation of a new 4,320 foot long Beverage (more so for lower frequencies) made me to decide to add some more protection. I added Taiwan Semiconductor's SRYH-90L gas tube surge voltage protectors (the $1.85 CATV models "with high current capability") across the resistors. Both have survived recent day's super wind static generator--60+ mph winds with sub 0 F temperatures.

Supporting the Beverage Wire

K9DX: I use 5/8 rebar eight feet long driven into the ground about 4 feet and slip an eight foot piece of thick wall plastic pipe over it. I put a hole about a half inch from the top of the plastic and saw a slot that I slip the wire through. Results: supports wire but allows the wire to slip back and forth. Has lasted Chicago winters fine.

Minimizing Common Mode Feedline Noise

W8JI: I recommend is adding a series common mode choke using a very high ui material, making the choke more like a large resistor than an inductor. I add a ground rod at ONE end of the choke, to provide a shunt impedance. K0FF: To wind an effective choke it takes big hi-mu torroid cores, stacked, and lots of coax. Using 2 or 3 stacked 2" cores, I wind them up with RG174 until they are full. Put an appropriate coax fitting on each end of the cable for I/O.The target is about 17 mH of inductance between the input and output terminals ( as low as 10 still works ). For 75 ohm feeds it is desirable to use 75 Ohm cable, but the only '174 size available in 75 Ohms is Teflon type and VERY expensive. In practice I use 50 Ohm RG 174 for everything, and a 3,000 foot roll lasts forever. By raising the series reactance to the common mode, it looks like a stone wall to any current flowing on the shield and center conductor simultaneously. From the standpoint of the desired signal, it looks just like an additional length of coax. On low frequencies the additional loss is negligible.

N1EU Home