Re: [IRCA] Synchros, anyone?

["Dan Strassberg" <dan.strassberg@xxxxxxx>]

SAH had me going for a while too. I think it must be short for sub-audio
harmonic, but between acronymfinder.com and acronymattic.com, I got well
over 50 possible definitions, of which none was sub-audio harmonic. In the
magazine I write for, the (excellent) rule is NO undefined acronyms unless
everyone in the readership (electronic engineers) ought to know them
(examples: AC, DC, RF).

As for the synchronicity of "synchros," with continued improvement in the
stability of quartz-crystal frequency standards, I think very few MW
stations with "synchro" transmitters do anything more than select closely
matched crystals for their transmitters. Some very elaborate schemes were
invented in the 30s, when crystal oscillators simply weren't stable enough.
I think that in the last few years of WBZ/WBZA, the two transmitters were
simply free running with well-matched crystals. WLLH, whose two 1-kW
transmitters are less than 10 miles apart, years ago gave up the exotic
technology. Over the years, the beat-frequency problem and the hash zone
appear to have become less and less important to reception of this station.

BTW, there used to be a station on 620 in Hawaii with a main Tx and two
synchros. IIRC, the main was 10 kW-U and each synchro was 5 kW-U. Because of
NIMBY concerns, one of those synchros had a very rare Paran antenna (four
very short, closely spaced towers supporting a massive top-load and behaving
as a single taller tower). I believe that both synchros are now dark; in
fact, the whole three-station "network" may now be dark. leaving a station
on 660 in WA (KAPS Mt Vernon?) 10 kW-D/1 kW-N ND-U with the only
remaining Paran in the US. IIRC, Mt Vernon is near Bellingham, which is hard
by the Canadian border. I remember picking up the station in October 1993
loud and clear on the rental-car radio in Seattle--of course 10 kW ND on 660
is nothing to sneeze at and there is salt water (Puget Sound) most of the
way from Mt Vernon to Seattle (maybe 60 miles).

--
Dan Strassberg, dan.strassberg@xxxxxxx
eFax 707-215-6367







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