Electrically, a half wave vertical dipole is not a lot different than a quarter wave vertical fed against radials or a counterpoise, but it requires a LOT more height to put it up. I just modeled tw
Very true, and that's essentially what N6BT's ZR antennas were. In general, of course, the feedpoint impedance goes down for a shortened antenna, which typically means the feedpoint efficiency suffer
Dielectric loading works as well in theory, but is obviously more difficult in practice. For grins one day I modeled an 80m vertical (fed against a couple of radials) with the vertical portion being
My gripe is with the unfounded performance claims. Dave AB7E I don't know that people are complaining about the *design* of the greyline vertical, more about the company's business practices. _____
That's not really a J-Pole. A J-Pole generally has a 1/2 wave vertical section, not a 1/4 wave. Since the end of a half wave is high impedance, the ladder line is used to get a match. If you only
PVC is a really, really bad idea. PVC can "cold flow" over time and there is very little chance it will hold much weight very long no matter what you do to support it. I agree with Jim Lux ... 4 inc
I would think that testing antennas today should be easier than it was when the K7LXC/N0AX report was done, and I don't see why an antenna range is even needed anymore. A wideband noise source mount
I've bought LOTS of black dacron line over the years because we used it for supporting various wire antennas in tall trees for Field Day. I bought most of it from Davis RF, and the stuff is still ho
How would that matter? It wouldn't make Rick's observation any less valid either way. Dave AB7E On 12/26/2020 11:45 AM, Steve Jones wrote: Rick, Do you have a K4 on order? 73, Steve N6SJ --Origina
Everyone here always recommends Amphenol 83-1SP PL-259 connectors, but does Amphenol make a crimp version? If so, where would be a good supplier of them? If not, what crimp connector out there has
Why do you want to point the antenna into the wind? I do just the opposite for my OB16-3 ... less stress on the elements. Depending upon the spacing, you could also be getting some resonance in the
If it is the tower that is vibrating, he could probably dampen it by putting tension on it with a length of rubber hose (or some other similarly mechanically lossy material). His tower is bracketed
I wonder if the survival odds are that much better for a laid over tower. Depending upon the direction of the wind, I'm picturing a 30 foot lever arm with the surface area of the antenna helping to
If you see thermal drift in the doorknobs caps due to high SWR, wait until you see what it does to the ferrite core in a common mode choke (see p.s. note below). Put the L-C match between the antenn
I have owned an OB2-40 (the non-Moxon version) for ten years and it has held up just fine to ridiculous wind gusts on my southern Arizona hillside. The antenna is built like the proverbial tank and
Sorry, but I don't believe any of that. It sounds purely anecdotal. 73, Dave AB7E On 5/21/2021 11:23 AM, Dave Thompson wrote: That optibeam sounds great but I reburbed my old 2 el Cushcraft 40 and
Well. I started out with a Prosistel PST-61D, and in addition to the OB2-40 I have a Optibeam OB16-3 on the mast. It worked fine for a few years, but eventually the wind gusts here stripped a sectio
Exactly! I'm not in favor of turning listservers into groups.io forums, but it would be nice somehow to have a sticky list of antenna myths (with explanations) to counteract the misinformation that p
Are you certain that what you are seeing isn't simply torsional twisting of the mast itself? I have a 20 foot 2 inch diameter chromoly mast with 5 feet inside the tower, an Optibeam OB16-3 about 3 f
If you didn't do side-by-side A-B comparisons then your comment is merely another anecdote. Dave AB7E On 5/27/2021 10:55 AM, John Kemker wrote: I've used OCFD on multiple bands for years and not no