Hy-Gain VB-28FM 2 Meter 8 Element Yagi Review
The Hy-Gain VB-28FM is a lightweight, low cost 8 element 2 meter Yagi beam antenna on a 12' boom. I purchased this to pair up with the VB-64DX 6 meter antenna reviewed earlier, which also has a 12' boom. The VB-28 is a hot performer gain-wise at 14 dBi. This gain is apparently the result of very high Q, which makes the antenna more sensitive to its environment than might be desired. The match de-tunes badly under snowy and icy conditions. It has a few other caveats as well, which I will explain shortly.
Except for the driven element, the rest of the elements are all made of small diameter rods. Therefore, you will not have the element vibration and breakage problem that is a concern with the VB-64. Even if you did, you could not remedy the problem by stuffing twine inside the elements since they are solid. The elements all pass through holes in the boom rather than mounting on top of it. They accomplish this by making rectangular holes in the boom such that stainless steel eye bolts can pass through. To mount each element, you insert the eye bolt and pass the element through it; then snug up the bolt to hold the element in place. When assembling the antenna, it is fairly easy to "miss" the element entirely, with the result that when you tighten the bolt, it will not secure the element. You have to be sure that the element actually passes through the eye to prevent this from happening. The best way to do this is to leave off the end caps and make a visual inspection by looking down through the center of the boom. I might also add that I did not join the two halves of the boom together until I was satisfied that all of the elements were secured correctly. At that point I also added the end caps to the boom.
The driven element mounts on a plastic insulator in such a way that you really can't align it to the other elements. On my unit, the driven element is out of line with the other elements by perhaps 10 or 15 degrees. Performance wise it is not a big deal; it's really more of an aesthetic thing, but it is a minor annoyance.
Like its 6 meter brother, the balun for the VB-28 is made of RG-58/U coax. I would recommend replacing it with one made of RG-8X at least, if you're going to run more than 100 watts. It's OK at that power level. If you're going to run the legal limit, definitely replace it with a good piece of low loss RG-8 type cable. The balun needs to be an electrical half wavelength. Be sure to take the velocity factor of the cable you use into consideration so your balun is the correct length.
Unless you feel compelled to tweak, there are no adjustments that need to be made once you finish assembling the antenna. The match on mine was very good at 144.2 MHz (1.1:1) with the antenna in its preferred mounting location. However, we had a surprise April snowstorm and as the snow started to come down, the VSWR began to climb. It went as high as 2.5:1 at the transmitter during the time I was observing. As soon as the snow melted, the VSWR came back down to 1.1:1. Given this behavior, I would tend to discourage anyone from buying this antenna for use at locations where snowfall is frequent. This represents a significant performance issue in many parts of the United States.
There were no issues with the coaxial connection to the driven element on this antenna. The one thing you need to pay attention to is be sure to properly seal the end of the feedline and the balun wires so that moisture does not get into the cables. These days I am leaning toward the use of liquid electrical tape for this purpose. Apply several thin layers rather than one thick layer and wait until each dries before adding the next layer.
As with most Yagi antennas, this one really "wants to work" and it exhbits a very pronounced pattern with good gain. For the money, it has good gain and F/B ratio, while exhibiting light weight and low wind load. You can turn this with an inexpensive television rotator. If you go up to the next larger model the price only jumps $10 (which is a steal!) but the boom length increases along with the wind load. I'm happy with the performance of the 8 element model.
To conclude, this antenna is an excellent value, with the one (significant) caveat that the match degrades noticeably when there is snow on the antenna. If you are concerned about that, I would recommend considering one of the Cushcraft models instead.
Except for the driven element, the rest of the elements are all made of small diameter rods. Therefore, you will not have the element vibration and breakage problem that is a concern with the VB-64. Even if you did, you could not remedy the problem by stuffing twine inside the elements since they are solid. The elements all pass through holes in the boom rather than mounting on top of it. They accomplish this by making rectangular holes in the boom such that stainless steel eye bolts can pass through. To mount each element, you insert the eye bolt and pass the element through it; then snug up the bolt to hold the element in place. When assembling the antenna, it is fairly easy to "miss" the element entirely, with the result that when you tighten the bolt, it will not secure the element. You have to be sure that the element actually passes through the eye to prevent this from happening. The best way to do this is to leave off the end caps and make a visual inspection by looking down through the center of the boom. I might also add that I did not join the two halves of the boom together until I was satisfied that all of the elements were secured correctly. At that point I also added the end caps to the boom.
The driven element mounts on a plastic insulator in such a way that you really can't align it to the other elements. On my unit, the driven element is out of line with the other elements by perhaps 10 or 15 degrees. Performance wise it is not a big deal; it's really more of an aesthetic thing, but it is a minor annoyance.
Like its 6 meter brother, the balun for the VB-28 is made of RG-58/U coax. I would recommend replacing it with one made of RG-8X at least, if you're going to run more than 100 watts. It's OK at that power level. If you're going to run the legal limit, definitely replace it with a good piece of low loss RG-8 type cable. The balun needs to be an electrical half wavelength. Be sure to take the velocity factor of the cable you use into consideration so your balun is the correct length.
Unless you feel compelled to tweak, there are no adjustments that need to be made once you finish assembling the antenna. The match on mine was very good at 144.2 MHz (1.1:1) with the antenna in its preferred mounting location. However, we had a surprise April snowstorm and as the snow started to come down, the VSWR began to climb. It went as high as 2.5:1 at the transmitter during the time I was observing. As soon as the snow melted, the VSWR came back down to 1.1:1. Given this behavior, I would tend to discourage anyone from buying this antenna for use at locations where snowfall is frequent. This represents a significant performance issue in many parts of the United States.
There were no issues with the coaxial connection to the driven element on this antenna. The one thing you need to pay attention to is be sure to properly seal the end of the feedline and the balun wires so that moisture does not get into the cables. These days I am leaning toward the use of liquid electrical tape for this purpose. Apply several thin layers rather than one thick layer and wait until each dries before adding the next layer.
As with most Yagi antennas, this one really "wants to work" and it exhbits a very pronounced pattern with good gain. For the money, it has good gain and F/B ratio, while exhibiting light weight and low wind load. You can turn this with an inexpensive television rotator. If you go up to the next larger model the price only jumps $10 (which is a steal!) but the boom length increases along with the wind load. I'm happy with the performance of the 8 element model.
To conclude, this antenna is an excellent value, with the one (significant) caveat that the match degrades noticeably when there is snow on the antenna. If you are concerned about that, I would recommend considering one of the Cushcraft models instead.