Originally Posted by steel guitar guy
... many years ago I had a CM 4251.. Bought it at a dealer and put it up myself.. however, it looks different than this one.. My old one had more elements in the parabolic grid, and they were smaller in diameter.. Same element size as most antennas..They were made more rigid with small aluminum wire snaps that clipped all the elements together.. It worked well..
| however this 4251 my friend gave me has huge thick elements as big around as a grown mans thumb,, It also kind of 'folds up when taken down,, which my old one did not.. My old one was not the smaller 6 foot 4250, I remember it very well.. I bought my first 4251 around 1975... My friend said his was up on his tower for 30 years, which would mean his was made in the late 80's... Were these units redesigned/changed at any points during their production?... bob
Are you sure you actually had a CM 4251? "Small aluminum wire snaps that clipped all the elements together" does not sound like Channel Master. Finco, one of their chief competitors, put out a parabolic dish for UHF that was their answer to Channel Master's 4251, and had the kind of clips you describe. IIRC, the CM 7-foot dish did not.
When I was in college in the late '70's, I worked summers with an electrical contractor who branched out his business into TV antenna installs, and we put up a few of them in the Irondequoit area near Lake Ontario, where the UHFs were relatively few and far between. Nothing else at the time had the kind of gain that the parabolics offered, except for some of the better 8-bay bowties, or maybe the 12-bay that TACO/Jerrold put out in the mid-1960s.
Those UHF parabolics were the "White Elephants" of the TV antenna industry. That's why Channel Master discontinued them. The sales guy at Crosstown Electronics in Buffalo told us that no other antenna got so frequently returned as the CM 7-foot dish. They eventually refused to carry them, and it was a shame, because Channel Master had the best quality back in those days before everything started to get made in Mexico and China. Problem was that the screwdriver jockeys and D-I-Y'ers who tried to put them up themselves would use regular TV masts that bent in the wind (HUGE wind load on those puppies, and a completely crazy center of gravity) and regular rotors would fail soon if you tried to use one to aim those monsters at a weak signal. They really were meant to be mounted in towers with at nothing less than ham radio-grade rotors, and guys were stickin' 'em up on roofs with in "El Cheapo" Archer Radio Shack tripods.
The irony is that those parabolics did
work well if you installed them carefully, and had plenty of forward gain as advertised, plus some really insane nulls and front-to-back ratios. I don't think they were ever re-designed; no reason to do that, everything about 'em, from the feed section design to the roll grade of the aluminum, was close to perfect.
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