-=> Quoting Roy J. Tellason to Joe Nicholson <=-

 RJT> That, and the fact that early tv sets weren't as selective
 RJT> in their front ends as later stuff was.

 Yep, I remember servicing a hundred brands in the 50's and
 early 60's.  The "good" stuff like Philco and Packard Bell
 had individual oscillator tuning to tweak the channels.

 Cheapies on the market like Sears and Mad Man Muntz had a
 single high band and a single low band oscillator adjustment.
 They were absolutely crap - 1 or 2 IF stages vs 3 or 4 used
 by the high-end brands.


 JN>  Someone had not taken into consideration inversion layers
 JN> which exist over some portions of the U.S.  They act as ducts,
 JN> funneling signals hundreds of miles away.

 RJT> Are these only in specific locations,  or what?
 
 Right, only specific locations.  At the time I was studying
 electronics and preparing for my FCC license, St. Louis and
 SoCal were the two areas that were most noteworthy/prominent.


 RJT> I can still remember some black-and-whites out there in the
 RJT> late 1960s that had those big whip antennas bolted to the
 RJT> rear bumper.  Don't remember who was using them, though.

 And the "secret" undercover cars used regular AM car
 antennas welded/soldered to a specific lenghth.  But
 I could hear the dynomotor a block away.  That always
 gave them away to a sharp ear.  
 

 JN> He hadn't realized they were old, old, old 2490kc AM
 JN> receivers and 72-75Mhz FM transmitters and were worthless
 JN> to hams (or anyone else).

 RJT> Hm.  No way to easily modify that stuff, eh?

 Can't modify AM transmitters to FM, nor FM to AM, and the
 frequency spread prohibited tuning them to the ham bands.
 Someone here recently questioned converting a scanner,
 154Mhz to 174Mhz, to the FM band, 88Mhz to 108Mhz.  Not
 only is the frequency spread too great for the conversion
 but the standards for FM broadcast and PS transmissions
 are totally different.

 Sidebar:  Motorola, GE, RCA manufacture radios for (about)
 130Mhz to 150Mhz (military frequencies used for on-base
 law enforcement, military fire departments, etc), and those
 companies also manufacture radios in the 150Mhz to 174Mhz
 range (civilian forestry/police/fire/taxi/railroads, etc).

 Even with that smaller frequency difference, a radio in
 one band cannot be tuned to frequencies in the other band.
 The "front ends" of each are totally different.

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