Xref: utzoo rec.audio:12484 sci.electronics:5963
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!xanth!mcnc!unccvax!dya
From: dya@unccvax.UUCP (York David Anthony @ WKTD, Wilmington, NC)
Newsgroups: rec.audio,sci.electronics
Subject: Re: Multiple AM Stereo Receivers
Keywords: AM stereo, FCC, technical standard
Message-ID: <1467@unccvax.UUCP>
Date: 25 Apr 89 16:23:25 GMT
References: <4058@bgsuvax.UUCP>
Organization: Univ. of NC at Charlotte, Charlotte, NC
Lines: 37

In article <4058@bgsuvax.UUCP>, klopfens@bgsuvax.UUCP (Bruce Klopfenstein) writes:
> While it is true that an AM stereo radio was possible which would
> receive any of the competing AM stereo systems, my understanding is 
> that such receivers would have cost at least $200 (I can check the
> NTIA report--one of them--to se for sure).  Since the general public
> (especially audiophiles) are not into AM radio anyway, how realistic
> would it be for them to spend that amount of money for an AM radio?

	This is pure hogwash (the price, that is).  I have both the
Sony SRF-A100 (the multimode table radio, AM-FM, $59.95) and the
Sony XR33-A (the multimode car stereo, AM-FM-stereo cassette, about
$140).  Both are wideband.

	No one seems to have a problem turning out C-QUAM receivers
by the zillions, and you can buy (from Leonard Kahn, no less) a retrofit
board which converts the Motorola C-QUAM chip into multimode.  It
is important to note that the C-QUAM chip is the subject of ongoing
litigation between Kahn and Motorola (patent infringment, among
other things).

	The **incremental cost** for stereo is very low, since you
have to provide the same front end that you do for mono.  In point
of fact, the C-QUAM decoder provides envelope detection for monaural
which you had to have anyway. (Actually, synchronous detection is
much better for the sum channel/monaural, another strike against
C-QUAM).

	As for suitable wideband IF amplifiers (where the locus of
the AM problem really resides) suitable monolithic ceramic filters
cost pennies in quantity.  I keep getting these rent-a-cars with
wideband IF amps (Toyota, Lincoln, Cadillac) so the inclusion 
must not be terribly expensive.

	Let's move this out of rec.ham-radio, BTW.....

York David Anthony
WKTD Wilmington, NC