Wondering if anyone has tried this base station antenna on their GMRS setup ? , lots of gain for the price , would like some feedback on its performance .
BRC HP-500 High Gain 460-470 Mhz GMRS Band Repeater Base Antenna-11.7dB Gain
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They’ve been about for a long time now. The majority are 3 5/8th stacked and have around 8-9dBd gain, which is pretty useful, and a low angle of radiation, great for repeaters. The critical downside is the joints. They’re plated and when first assembled you need to make sure they are done up really tight. Tight enough you can’t get them apart, then you need to water seal them. Heat shrink and self-amalgamating tape at the least. I’ve heard one person advocating epoxy. The problem is the machining is quick and dirty, so when they are tight, sometimes, at that point in the rotation the faces are not parallel so the water can get in, corrode where it settles on surfaces where the screwing in has exposed the real metal and after a few months, your performance degrades.
They’re also quite heavy and being tall, they need a really solid mast. Normal thin wall tube bends and fractures with the constant flexing, so for anything other than short, it means 2” support tube.
The flexing also means really good fixings.
If I really needed the gain, I’d happily use one.
How can it be 3 5/8 wave stacked?
At GMRS frequencies, that amounts to 4 feet of antenna. So how does that become 17 feet?
I am sorry I bought it to replace my storm-destroyed Comet CA-712EFC. It worked a lot better than the BRC HP-500, at almost half the height.
3 x 5/8th for VHF, but 7 x 5/8th at UHF. If the bandwidth works for you, they’re ok, just stupidly long, but with adequate mounting, OK. I’d not put one on my house chimney, they’re not substantial enough, but with proper bracketry, I could do it.
I suspect they’re just a tweaked version of the old diamond design, which was of course, a dual band antenna.
Thanks, Paul… That would make more sense. 7x5/8 at GMRS UHF.
I took apart the Comet CA-712EFC and found it was a collinear coaxial antenna of 12 elements and what appeared to be some kind of matching network of two stub coax elements. I may see if I can’t rebuild the coax internals.
I am wondering if these are not 2m/70cm antennas, with tuning to make them suitable for GMRS.
I think they absolutely are! The spec on some sites includes the VHF spec.
My only thoughts are that if you buy commercial UHF antennas they very rarely get more than four stacked dipoles. Occasionally you might get two of these linked, but the losses build up so it’s very hard to make the real performance match the published one. My guess on this antenna is that the spec comes from the physics, but the retuning and tweaking to shift the resonant portion probably means the actual performance is way don on the claim.