| N6XI |
Rating:  |
2024-07-02 | |
| Robust, multi-band, single feedline antenna |
Time Owned: 0 to 3 months. |
This antenna replaces an old 4el 20-6M SteppIR that needed refurbishment. I wanted a single feedline, 5- or 6-band, low maintenance antenna that could go up on the same day that the old one came down. I didn't have mast or cable conduit space for separate contest- and WARC-band beams and my 6-pack antenna switch was full. So the Optibeam fit the bill. It's "built like a tank" and will probably outlast my tenure at its mountain ridge location. Performance appears to match spec, at least subjectively. I've made dozens of contacts in its first two days on 20, 17, 15, 12, and 10M on CW, FT8, and SSB with the same kinds of signal reports and ease of contact that I was accustomed to with the longer, floppier SteppIR. It even loads nicely and has made a few Qs on 6M, not an officially supported band.
The outstanding characteristics of this antenna are mechanical design, ease of assembly, packaging, and support. The tubing for each element is labeled, pre-drilled, nested, and taped together. You can't fail to find all the pieces or confuse their assembly positions. To assemble the elements there are four sizes of bolts requiring only two sizes of nuts and the nuts are cap-style, requiring no lock washers. (Hint: five paper bowls on the assembly table) There are lots of spares in case your yard is hungrier than mine. (I only lost one nut.) Everything fits together perfectly. The instructions are in good, second-language English and easy to understand.
This beam uses a square boom, unusual in the antenna business and just wonderful! There is no way for elements to tilt on the boom or for the boom to roll on the boom-to-mast plate. Square U-bolts make for easy, intuitive assembly. The drive system is complex, much like a log periodic array, with a pair of hefty phasing bars running most of the length of the antenna, coupling directly or with cross-over tabs to 11 of the 12 elements. The elements and phasing bars end up under the boom, so the recommended assembly procedure, all but mandatory IMHO, is to assemble the boom, element center sections, boom-to-element plates, phasing bars, balun, and shorting stub with the boom upside-down on saw horses. At that point, you have a 25' long boom with short center sections that's easy for two people to invert for subsequent assembly of the element extensions, boom truss, and boom-to-mast plate. In my situation, I did the upside-down steps in the driveway before an easy two-person carry out to the antenna meadow where I built out the element extensions in the shadow of their intended home, a US Tower HDX-672 (sic) heavy-duty tower that also supports a 2el 40M and an 80M rotary dipole. Once completed, it's a four-person lift into position for raising.
The tubing has thicker walls than most antennas I have built, with generous overlap. The instructions don't call for conductive grease but I used some anyway. The pre-drilled screw holes are larger on one side so the screw heads fit partially inside the hole instead of resting on top of the tube, very sturdy and requiring only one screw per junction. The hardware looks and feels a cut above typical amateur antenna parts. In case you still don't have any metric tools, Optibeam includes two hex wrenches and a two-size socket tube-wrench. For most connections, I recommend a ratchet wrench. Deep sockets were helpful in some places and a few begged for box-end wrenches.
The element-to-boom plates, phasing bars, cross-over tabs, boom truss, and 300x300mm boom-to-mast plate are hefty. Nothing on this antenna is likely ever to bend, break, or slip. I am confident it will survive the winds, snow, and ice of many High Sierra winters. I'm very impressed with the mechanical design and packaging, as were the four other hams who helped with the lift.
Speaking of the lift operation, the gap between elements around the boom-to-mast plate was too narrow for my chubby tower, so we used a trolley line to haul the antenna up to the tower, element tips first, to slide around the top section and mast. With manned tag lines over both ends of the boom and a back stay on the mast, erection was pretty straight-forward. Only one climber was needed on the tower. Nothing bent, broke, or caused undue angst and the beam went up promptly.
The photos in the manual are good, not great, and left me scratching my head over balun connection and shorting stub adjustment. The balun connects exactly as one would expect but the photo wasn't clear to me, probably "my bad." The shorting stub as shipped didn't match the photo which was from a different model in the Optibeam product line. But owner Tom DF2BO was very responsive to email inquiries and clarified several questions same day or overnight, even as he was super-busy preparing for Ham Radio Friedrichshafen. Nine time zones away, and he was more responsive than most US manufacturers!
Shipping was complicated, involving three separate carriers, two of which often subrogate last mile delivery to USPS who refuse to deliver to my underprivileged address. I learned of these shipping arrangements only after they had launched. Fortunately, DXE were able to redirect the two at-risk packages to a viable address and all three packages eventually arrived. The antenna was ready to go two days before the climber appointment that I had made a month earlier.
I highly recommend this antenna. The OBDYA-12-5 looks like a long-term winner. I plan to update this review after I have some contest experience with the beam. |
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| VK2PW |
Rating: |
2023-12-29 | |
| Absolutely Terrific Antenna |
Time Owned: 0 to 3 months. |
Well, from the day I ordered the antenna to the day it was flying, the support from Optibeam (Tom DF2BO) was second to none. Every question answered with attention to detail like you just don't expect these days. All the specifications of the antenna were explained and comparisons made, expectations I could count on etc. To summarise the support from Optibeam, its just in a class of its own really, little more needs to be said.
The construction of the antenna was straightforwards, many of the components are already together such as the phasing bars. I was anxious about constructing the antenna. From what I had read online, the instruction manual was just a text based document. I was concerned about language barrier issues from the German dialect to English. My anxiety was put to rest when it arrived easy to read and interpret. In my honest opinion, the antenna is practically telling you what you need to do, its almost too obvious! I doubt most people would be confused.
There is minimal use of hardware involved, it all makes sense what goes where, every part that goes with every part is identified and numbered accurately. You can hardly go wrong really. The hardest part for me was figuring out how the bolts go that lock all the element whips together. I did stuff that up at first and had to do them again. Tom told me to read the WHOLE manual, I should have listened. Please do so, its not hard, just not what you might expect, I assumed and I was wrong on those element bolts, all good was only a bruise to my ego and easily sorted out.
As with any new antenna, you worry the SWR wont be right, that somehow something might not connect properly or you put the wrong connector on the wrong bolt. No such luck, the antenna went in the air and the SWR was picture perfect on every band. 20m 1.1, 17m 1.1, 15m 1.0, 12m 1.0, 10m 1.0 to 1. You could not wipe the smile off my face. I went from a Dynamic antenna so I had to get it right. There are no adjustments to be made, the antenna is all predrilled to perform as it was modelled and designed, you don't just adjust it to make it work. If its not right, you've done something wrong and you will need to figure out where you messed up but it was PERFECT! And it has never changed from that on all those band measurments detailed above. Steady, stable and dependable SWR. Jump on a band and TX, no need to worry - its dead on every time.
Performance....just amazing! Compared to my other dynamic antenna, its a pretty big step up, id say its giving performance close to a 4 Element full size yagi on all the bands and perhaps as much as say 4.5 elements on 10m. It is so very quiet on the bands I assume thanks to the excellent front to back ratios. On 15m the noise floor sounds like soft gentle rain outside smooth and untroubling. Like a beach or shorline meditation tape. Try not to fall asleep!!!
I was able to hear clearly the very faintest of CW signals during the CQ WW CW competition. I entered just to see how it performed and it did very well indeed for the short time period I was operational during the comp. You know you have worked a very weak QRP CW station when you get them in the log and you get the extra TU TU TUs 73s from them. Nice feeling to know you've made a little stations night.
Visually, it is a very nice looking antenna. Its fine lines make it appear like a Log Periodic although it does not function like a log so I understand. About 70-90% of the entire antenna area radiates and receives giving a substantial performance gain over your typical yagi. Even the front passive element radiates, yes I know how can it? I am told it does, only its in miniscule db values but hey, something is better than nothing right?
I am a very happy customer, I trust it will give me no trouble for decades. When you build it, you just get this good feeling like "what could fail", its just so well designed and the construction is top deck. My intention is to take good care of it with periodic maintenace so that I never have to replace it. It will do me just fine for my meager little station.
Danke Tom, danke Optibeam!
The OBDYA 12-5 Driven Yagi Array
VERY HAPPY!
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