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The History of FM Radio

The technical side of broadcasting. Think IBOC is a sham? Talk about it here! How about HDTV? Post DX reports here as well.
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Ben Zonia
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Re: The History of FM Radio

Post by Ben Zonia » Thu Mar 04, 2021 9:54 am

The W45D 44.5 MHz antenna on the top of the Penobscot Building. A 2 Bay Horizontally Polarized Turnstile. It looks like the elements are at least initially tunable by pulling the smaller telescoping sections in and out. Somewhere I saw the name of the engineer who installed it. Considering that the wavelength is 22 feet and the engineer is circa 6 feet, the spacing is nowhere near optimal for much gain.

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Ben Zonia
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Re: The History of FM Radio

Post by Ben Zonia » Thu Mar 04, 2021 10:37 am

WWJ-FM then moved to 8 Mile on the taller WWJ AM tower, then applied in 1961 for 500 kW from 892 feet, essentially its present AGL/HAAT site on the WDIV Channel 4 tower. It was backed down to 50 kW from 500 feet, then 12 kW from 893 feet, and when the ERP/HAAT curves were redrawn, 15 kW from 893 feet.

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k8jd
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Re: The History of FM Radio

Post by k8jd » Sat Mar 06, 2021 5:26 pm

The calllsigns for today's FM band translators and low power stations follow almost the same method of issue as the older 40 MHz band. the numbers are the "channel" number for the freq used.



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Re: The History of FM Radio

Post by Deleted User 15506 » Sat Mar 06, 2021 6:31 pm

How bad would the interference level be on the old FM band? Would W45D have the same coverage area as most current FM stations today? And would we have the same skip conditions as today? Would DX’ing be better or worse than the current FM band? before the great translator invasion.



k8jd
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Re: The History of FM Radio

Post by k8jd » Sun Mar 07, 2021 4:27 pm

OLDE FM Band problems
the FM band at 45 MHz would have had seasonal E-skip interference at quite substantial levels from up to a thousand miles away.
I played with a few 6 meter stations here (50-54 MHz) over the decades, and my last setup used 8 W peak output on SSB and a 4 element Yagi antenna. I had good reports from the Rocky Mountain states and new England and the Carolina and Gulf coasts. I imagine there would be problems in the fringe areas of a 45 MHz signal coverage during the twice yearly openings. During the high sunspot years this band opens up to long haul much more often.



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