Hy-Gain VB-64DX 6 Meter 4 Element Yagi Review
The Hy-Gain VB-64DX is a lightweight and relatively low cost 4 element 6 meter Yagi beam antenna. I bought this a couple of years ago and put it up last year on an inexpensive television rotator mounted just above the roof of my single story house. It was a huge improvement in performance over the omnidirectional squalo type antenna that preceded it. The squalo picked up way too much noise from all directions, including noise generated by equipment inside the house. And of course, it had no gain.
The VB-64DX is a decent antenna and will give good performance if built and installed with care and attention to detail. I'd like to share a few hints that will be very helpful if you decide to build this antenna. First of all, there is a significant mechanical issue with the antenna that you need to address right away. The small clamps that are used to attach the coax feedline and the balun to the driven element are too large and will not secure these connections properly. Further, the material is weak and bends easily. You have a few options if you want to use these clamps. You can increase the diameter of the 5/8" tubing by wrapping some thin aluminum shim stock around it to make the clamps hold more securely. You can use hose clamps instead and trap the cable connections under them. Or, you could replace the supplied clamps with stronger ones if you can find any that are suitable. I had the thought of using pipe hanger clamps, which are much stronger, but unfortunately I could only find 1/2" or 3/4" clamps locally. I think the 5/8" clamps used by Cushcraft on some of their antennas might work, but I have not tried them. The part number of these is 171329. These can be ordered directly from them.
If you are going to run more than about 100 watts on 6 meters with this antenna, make a new balun with larger coax to replace the supplied balun which is made out of RG-58/U. I think good quality RG-8X cable should be perfectly satisfactory unless you are running the legal limit, in which case you should probably go with an RG-8/U variety. I like the RG-8X cable sold by DX Engineering because it's easy to work with. Your replacement balun might need to be a different length than the one that came with the antenna, because you need to take the velocity factor of the cable you are going to use into account. Do not overlook this when making your new balun. It needs to be an electrical half wavelength long to work properly.
The next thing to be aware of is that you will need to measure and position all of the elements very precisely. Nothing is marked and nothing is drilled; it's up to you how long to make the elements and where they are positioned along the boom. This does give you a lot of latitude in terms of what frequency you want to optimize performance for. I was only interested in the low end of the band, so I used their stock measurements for that. I did have to adjust the length of the driven element slightly to optimize the match at 50.2 MHz.
The last point I want to mention is that it is absolutely critical to follow the suggestion in the instructions to install twine inside each of the elements to dampen vibrations. It is easy to overlook this point in your enthusiasm to get the antenna assembled and installed. But if you ignore it, you will likely end up with broken elements. One day not long after I had installed the beam, I was up on the roof doing some other work and noticed the elements vibrating strongly, although there was just a light breeze at the time. I quickly realized that these vibrations would rapidly deteriorate the aluminum causing the elements to break off. I have read a number of complaints online about broken elements on this antenna and other similar ones, and conclude that most likely, the owners failed to install the twine. The purpose of the twine is to dampen the vibrations. It does not need to be heavy, and in fact you probably would want to avoid heavy ropes inside the elements, but you should try to use a larger diameter if possible to obtain the maximum damping effect. I found it easiest to remove each element completely (if already installed) and use a stiff piece of wire to pull the rope through. When you're done you can reattach the element and the end cap. Don't think that just because you don't live in Iowa or Kansas you can get away without installing the twine. It only takes a little breeze to excite the vibrations.
I think that for the price, this antenna is an excellent value. It is one of least expensive, lightest weight, and highest performing antennas available commercially. I have not noticed any problems with the match changing under wet or icy conditions. Is it an LFA? No, but for many hams it will do the job quite well. You will notice that this antenna has just 4 elements on a 12 foot boom, whereas most of its similar competitors have 5 elements. Does this matter? Not really. If you read the W2PV Yagi Antenna Design Book, you will discover that 4 elements can work as well as 5 on a boom of this length. The use of one less element makes for a cleaner look and more importantly, reduces weight and wind load. These can be important considerations if you have a difficult mounting situation. I do recommend this antenna, and if you are careful building it, you will obtain very good performance.
The VB-64DX is a decent antenna and will give good performance if built and installed with care and attention to detail. I'd like to share a few hints that will be very helpful if you decide to build this antenna. First of all, there is a significant mechanical issue with the antenna that you need to address right away. The small clamps that are used to attach the coax feedline and the balun to the driven element are too large and will not secure these connections properly. Further, the material is weak and bends easily. You have a few options if you want to use these clamps. You can increase the diameter of the 5/8" tubing by wrapping some thin aluminum shim stock around it to make the clamps hold more securely. You can use hose clamps instead and trap the cable connections under them. Or, you could replace the supplied clamps with stronger ones if you can find any that are suitable. I had the thought of using pipe hanger clamps, which are much stronger, but unfortunately I could only find 1/2" or 3/4" clamps locally. I think the 5/8" clamps used by Cushcraft on some of their antennas might work, but I have not tried them. The part number of these is 171329. These can be ordered directly from them.
If you are going to run more than about 100 watts on 6 meters with this antenna, make a new balun with larger coax to replace the supplied balun which is made out of RG-58/U. I think good quality RG-8X cable should be perfectly satisfactory unless you are running the legal limit, in which case you should probably go with an RG-8/U variety. I like the RG-8X cable sold by DX Engineering because it's easy to work with. Your replacement balun might need to be a different length than the one that came with the antenna, because you need to take the velocity factor of the cable you are going to use into account. Do not overlook this when making your new balun. It needs to be an electrical half wavelength long to work properly.
The next thing to be aware of is that you will need to measure and position all of the elements very precisely. Nothing is marked and nothing is drilled; it's up to you how long to make the elements and where they are positioned along the boom. This does give you a lot of latitude in terms of what frequency you want to optimize performance for. I was only interested in the low end of the band, so I used their stock measurements for that. I did have to adjust the length of the driven element slightly to optimize the match at 50.2 MHz.
The last point I want to mention is that it is absolutely critical to follow the suggestion in the instructions to install twine inside each of the elements to dampen vibrations. It is easy to overlook this point in your enthusiasm to get the antenna assembled and installed. But if you ignore it, you will likely end up with broken elements. One day not long after I had installed the beam, I was up on the roof doing some other work and noticed the elements vibrating strongly, although there was just a light breeze at the time. I quickly realized that these vibrations would rapidly deteriorate the aluminum causing the elements to break off. I have read a number of complaints online about broken elements on this antenna and other similar ones, and conclude that most likely, the owners failed to install the twine. The purpose of the twine is to dampen the vibrations. It does not need to be heavy, and in fact you probably would want to avoid heavy ropes inside the elements, but you should try to use a larger diameter if possible to obtain the maximum damping effect. I found it easiest to remove each element completely (if already installed) and use a stiff piece of wire to pull the rope through. When you're done you can reattach the element and the end cap. Don't think that just because you don't live in Iowa or Kansas you can get away without installing the twine. It only takes a little breeze to excite the vibrations.
I think that for the price, this antenna is an excellent value. It is one of least expensive, lightest weight, and highest performing antennas available commercially. I have not noticed any problems with the match changing under wet or icy conditions. Is it an LFA? No, but for many hams it will do the job quite well. You will notice that this antenna has just 4 elements on a 12 foot boom, whereas most of its similar competitors have 5 elements. Does this matter? Not really. If you read the W2PV Yagi Antenna Design Book, you will discover that 4 elements can work as well as 5 on a boom of this length. The use of one less element makes for a cleaner look and more importantly, reduces weight and wind load. These can be important considerations if you have a difficult mounting situation. I do recommend this antenna, and if you are careful building it, you will obtain very good performance.