Category Archives: Antennas
As I have become more interested in Contesting, I have met some top contest operators in my Local Contest Club, and have been looking for some antenna improvements for my modest Station at KG3V in White Stone, VA.
My current antennas include an 80m half-wave dipole on all Bands (with an external Tuner), and a ZS6BKW on 80m, 40m, 20m, and 10m. I also have a trapped vertical for 10m – 40m attached to a pier on the shore of the Chesapeake Bay with just a few radials. This is pretty basic stuff, with lots of room for improvement.
In antenna discussions and through a couple trips the World-class contest Station at NR4M, which we call the Goat Farm, I was hearing about Receive-only Antennas. That is nothing I had ever tried, but it sounded interesting. If these guys are using them, my bet was that they were a useful addition to my station if I hoped to extend my reach around the Globe in Contests (or in day-to-day operating).
One Receive-only Antenna that has been very popular is the Beverage Antenna. I have heard the name, but never really investigated these antennas. Since I have a couple hundred feet of property line, it seemed like a good thing to try. So I ordered a few hundred feet of RG-6 coax for a feedline, and the basic Beverage antenna system components from DX Engineering. I already had spools with at least 500 feet of # 14 AWG single-conductor. house wire for the antenna element.
There are many great articles and book chapters devoted to these types of antennas, so I will not attempt to rehash the basic beverage concept. I will just say that all you need is a few hundred feet of wire at about 7-10 feet above ground (and now there are even models that you can lay on the ground – called Beverage-on-ground or BOG). This sounded like the kind of antenna installation I couldn’t resist – no climbing or treetops to deal with. It sounded so easy that if it worked at all, I was getting something for almost nothing.
I got some electric fence insulators and attached them to a line of trees along my property line at about the 7-foot level. I put a ground rod at each end, and mounted the DX Engineering components – a single small box at one end and a resistor at the other end. Then I ran the feedline to the shack. I oriented the antenna so it would favor Europe, and hopefully even further to the East from my QTH.
Both of my primary radios have built-in provisions for using a separate Receive-antenna, and you will find this on many other modern HF Transceivers. If yours does not have this, you can buy or build a relay system for the purpose. The setup was very easy. My Beverage is somewhere around 240 feet long. That is rather short, but I was expecting it to be usable on some of the lower HF Bands. I think it is really too short to be any help on 106m, border line on 80m, but offers Beverage-like characteristics on 40m and maybe on 20m.
What I found was that the antenna was a big help late at night on 80m, and at other times on 40m as well. It definitely favored Europe, and helped knock down some of the W5 superstations by several S-units. It also had a much lower noise level than my wires hanging in the trees.
The one issue with a Beverage is that it is not a Gain antenna. It is very lossy, so all signals are down significantly from a dipole. This can be remedied by adding some amplification, as long as you do not add so much that you raise the noise floor too much. I just used the built-in preamps on my Receivers and had pretty good results. I only had a few hours to work this Contest, but I will try to get some more meaningful measurements soon, and will post them.
The RT-424 is a 4.5 foot tall roof-mounted tower for rotatable antennas.
As I have heard, this looks like a nice product but the instructions leave something to be desired – something HUGE. Here are a few notes and warnings from my assembly process.
Things you MUST know:
- There are 28 bolts, and eight of them are shorter than the others. You must use the 8 shorter bolts in the top section to secure the thrust-bearing plate. otherwise (if you use the longer ones), it will not be possible to assemble it.
- If you tighten everything as you build the tower from the ground-upwards, you will not be able to align the holes to attache the thrust-bearing plate (unless you are very lucky).
Some General Observations
The pieces came well packaged, with the hardware in one of those multi-section shrinkwrap bags.
The machining appears to be well done but they did not deburr the holes on my parts. Be careful, you could get a nice cut from the sharp edges.
Some Assembly Photos and Suggestions
When assembling the tower, leave all hardware loose enough that you can move around the parts, until you are ready to put on the top thrust-bearing plate. I suggest starting by attaching two-each of the cross-braces to each of the legs using the top bolt for each brace, as shown below.
Next attach one of the rotor plates between each pair of legs, and then attache the lower portion of the cross-braces between the two legs.
Here is a closeup showing the attachment of the braces and the rotor plates.
Next, attach the cross-braces between the two pairs of legs Now you have the entire tower together. If you tried tightening all the hardware as you built the tower, you might now have a situation like mine shown below, where you can not possibly align the holes to attach the thrust-bearing plate.
Once everything is loose enough, install the thrust bearing plates, then tighten all the hardware starting from the top. The top plate should align nicely like this:
Now attach the feet on the bottom and your tower is ready to mount on the roof. Here is a shot of the completed 4.5 foot RT-424 tower. Good luck.
I have been looking at a way to get a Yagi on my roof. No room for a big tower at my QTH, but something on the roof is within reason. I have been looking at the Glen Martin Roof Towers, particularly the smaller Glen Martin RT-424 Roof Tower. It is a 4.5 foot tall, four-legged “quad pod.” The prices on these have suddenly been reduced substantially, so I finally placed an order.
I received the package a couple days ago. Today I decided to put it together. It is a lousy day here anyway, so I will build it in the garage. The box was surprisingly small. They did a good packaging job. Just a bunch of pieces of machined aluminum, a shrink-wrapped container of hardware and a 4-page manual.
Looking at reviews on eHam, it appears to be a good quality item, with not-so-great instructions. With a couple pictures in the manual, it looks like is should be fairly easy to build.
I will post some of my findings as I put it together. Hopefully everything I need is there. I still need to find a rotor for the rooftop setup. The antenna will be a used C3S 10/15/20 meter yagi that I bought a few months ago. This will be the first yagi I have had in a station for many years, so it should be fun.
As I try to continually improve my Station, I keep coming back to the antennas. I have a couple very nice Radios, but I am still not very competitive in Contests, especially DX contests. I have always used mainly wire antennas and generally if I can hear them, I can work them. Now I know the problem is that I can not hear enough of them!
I had an opportunity to work a Contest from a world-class Contest station (NR4M) recently. The contest was the ARRL International DX CW. I won’t go into the details of the antenna system there (you can search on NR4M), but let’s just say they have about 65 acres worth of antennas like I will probably never see anywhere else.
I had access to all kinds of antennas on all the HF Bands. One antenna group that really impressed me was on 80 meters. I heard all kinds of DX during the weekend and I even managed to work China on 80 meters. That will not be happening at my Home QTH any time soon. I was using two antennas at the time, in Diversity Mode on a K3. This was quite a new experience. The diversity did just enough to bring the China station’s signal out of the noise enough for me to work him.
So the lesson learned here is that if I really want to improve my station and get to the next level, I have to do something about the antennas. First project is going to be getting a yagi on the roof. I will always use wire antennas, and I will be trying to improve them as well. I recently installed a Beverage antenna for the first time. At a length of about 300′, it is not very long, but I am hoping it will improve my hearing ability on the Low Bands.
Of course another thing I could do is raise my Power to the KW level. I do not plan to do that, mainly due to the small lot I am on and the close proximity of my antennas to the Shack. I think going QRO would result in an RFI nightmare.
UPDATE – Just to set the record straight, I no longer believe that RF was what caused my F-150 to lose its mind. I had a similar problem not too long again, and there was no Contest. Ford had to replace some wiring harness inside the transmission ($$$$$$ for them). That seems to have fixed the problem.
After a weekend-long CW contest at my Home, I jumped into my Ford F-150 to head out, and it was acting very strange. It seemed like the automatic transmission was dead or dying. I knew it was a little touchy going into 2nd gear at times, but it had been working just fine when I parked it for the weekend. I thought my week was ruined and I would have to call for a tow of my truck for an expensive transmission repair.
As I headed out of the driveway, shifting was still awkward. Then I noticed that as it changed gears, the dash display still said I was in 3rd gear. Once I saw that I knew something was fishy. So I went back to the house. I went through a couple power on-off cycles and things started to change. The dash display went nuts briefly, but then it started to come back to normal.
Seeing this change in behavior made me finally realize what had happened. I had parked the truck with its HF rig and screwdriver antenna right under one of my wire antennas, a ZS6BKW. The tip of the truck’s HF whip was directly under the antenna and only about 20 feet away. My guess is that there was RF coupling between the Home antenna and the wiring in the truck. As a result of the RF, some computer memory in the truck got corrupted. Eventually the vehicle must have loaded some historical or factory settings. After that, all was well again.
So now, when I park near the Home HF antennas, I remove the whip from the truck. I plan to do some more RFI mitigation soon, but for now this seems to have solved the problem.
Here we go again. Time for ARRL Sweepstakes CW (SSCW) 2014. Same plan as always – main objective is to get a personal high score. Secondary objective is to get that elusive “clean sweep” – all US and Canada Sections in one weekend. I have been within 1 or 2 sections the last several years, with Nebraska being the holdout last year. Never even heard it! Yes, really, NEBRASKA. Oh well..
I always like to try a new antenna or 2 for SS. This year I may need them as the forecast is for high winds nearly all weekend. Got 4 antennas and two radios for the hunt this year.
- 80m dipole, ladder line fed, usable on all other HF Bands as a doublet
- ZS6BKW oriented E-W
- ZS6BKW offset 45 degrees from antenna #2
- 6BTV Vertical on a pier over the Chesapeake Bay
The radios are an ICOM IC-7600 and an Elecraft K2
I have no idea how I will do in terms of score, but I know I will have fun. Hopefully one or two of the antennas will still be standing when Sunday night gets here.
I had an HT (Kenwood TH-F6A) connected to an antenna switch, connected to the two antennas. I tuned to a weak repeater. I found that I could hear it with the roof-mounted antenna, but not with the door-mounted antenna. I could switch the antennas between the 2 mounts with the same result, so it was the mount or the mount location making the difference.
When I opened the door with the antenna on it (moving the antenna and mount away from the chassis), I suddenly could copy the repeater with either antenna. I had the bottom of the door-mounted antenna about 4 inches below the roof line. moving it up about 2.5 inches made a huge difference in reception.
So if you are using one of the door-edge mounts, you may want to experiment with the placement.
Well I kept up the time-honored tradition of missing 1 or 2 Sections in the CW SS contest this year. Had about 575 QSOs (a personal best) and all but 2 Sections – MB and NNY. I never had trouble with a New York section before. I guess the monster storm Sandy may have been the reason, as they were all trying to get their lives back together and probably had little time for playing with radios.
I did not make any further adjustments of my ZS6BKW (ref: earlier posts on this subject). The SWR was well within usable range for the CW Band segments and I did not want to jeopardize that just before the Contest. Now that CWSS is over, I may get back to some final tweaking of this antenna to see if I can get 80m Phone in the 3:1 range needed by the IC-7600’s internal tuner.
I did try the 20m 4-element colinear antenna this year. I can’t say I was real impressed. I guess a fixed antenna with higher gain is not really what I want. Next year I may go to something rotatable. I did pickup a couple sections with the colinear that I could not get with my other wire antennas, but overall I am not sure it was worth the trouble.
Well, hurricane Sandy did no damage to my Chesapeake Bayside QTH. I am thankful for that and I wish a quick recovery to those that were ravaged by this nasty storm. The winds did leave one of my antennas needing attention. The winds pulled my anchor for the center of my ZS6BKW antenna out of the ground and it is now hanging in mid air. This should not be difficult to fix.
I see from last year that we also had high winds just before SS in 2011. Guess I should expect more of that in the future. It is calm now but they are expecting fairly high winds all weekend. I will need to clean up my two existing antennas and I hope to hang the 4 element 20m colinear array on my Penninger Tilt-up mast.
Inside, my station is all ready to go for the contest. I have an SO2R setup using the Icom IC-7600 and an Elecraft K2. This year I will also be using some ICE Bandpass filters to try and reduce the Band-to-Band interference I had in past years. I tested the station, including the DX Doubler, last weekend when I operated a couple hours in the CQWWDX SSB contest. I got about 48 Contacts and added a good number of new Countries in the Log.
I really like the SO2R setup with the DX Doubler and N1MM software. I think I have all the technology pieces in place now. Hopefully I can ramp-up the Sweepstakes operation this year. I will be looking once again for that elusive (for me anyway) Clean Sweep. 83 Sections are needed this year for the Broom.
The ZS6BKW Antenna is one of many HF multi-band wire antennas. It is similar to the famous G5RV antenna, which can cover multiple HF Bands but requires an antenna tuner on most bands. The ZS6BKW follows the design of the G5RV, but makes improvements. These improvements allow it to be used on more bands, and to exhibit better SWR on several Bands. There is an excellent article that compares these two antennas, and it shows me that this is a better bet for my station than the G5RV.
I built the ZS6BKW and am now starting the tuning process for my location. I have many trees, so any wire antenna I build needs some pruning, no matter how I model it. I used standard household 14 gauge wire for my antenna and fed it with 450 ohm ladder line. I used the “fat” 450 ohm ladder-line (about 1.5 inches wide), because that is what I have available. My ladder-line uses solid number 14 conductors. That makes it a bit hard to work with, but it holds up very well to the elements at my Bayside QTH.
The one thing I dislike about this antenna is that it is not expected to work on 15 meters, where it has a very high SWR. I can use my 135′ dipole on all bands with my antenna tuner, so I am wondering if this antenna gives me any advantage over that. It is shorter, but I have room for the 135′ wire, so maybe this is a compromise I do not need.
I will be trying it and tweaking the dimensions. I’ll post my results for anyone that may be interested in the ZS6BKW.