From: sehari@iastate.edu (Babak Sehari)
Subject: Re: FM stereo in TIME domain.How does stereo FM radio work?)
Originator: sehari@vincent1.iastate.edu
Organization: Iowa State University of Science and Technology, Ames, Iowa.
Distribution: usa
Date: Wed, 7 Oct 1992 04:51:57 GMT

In <1992Oct6.194009.2168@lmpsbbs.comm.mot.com> Scottl@mot.com (Scott Lindsey) writes:

>In article <1992Oct05.172142.5600@ssc.com>, markz@ssc.com (Mark Zenier) writes:
>> 
>> jeh@cmkrnl.com writes:
>> : In article <1992Oct03.042813.15261@ssc.com>, markz@ssc.com (Mark Zenier) writes:
>> : > In article <1992Oct1.165659.8131@bnr.ca> mwandel@bnr.ca (Markus Wandel) writes:
>> : >>Say that everything was based on square waves, and that you started out
>> : >>with a 38KHz clock waveform.  Based on this clock, you alternately select
>> : >>the left or the right channel for transmission, transmitting a sequence
>> : >>of samples L, R, L, R, L, R, etc.  
>> : > 
>> : > Did any commercial gear work this way?
>> : 
>> : Someone else mentioned that at least one of Heath's top-of-the-line receivers
>> : did.  And many (most?  all?) recent color tvs demodulate the 3.58 MHz chroma
>> : subcarrier this way. 
>> 
>> Sorry, the question should have been: Do commerical FM stereo transmitters
>> work this way?  (I've been trying to come up with a cheap stable FM stereo
>> exciter for a couple of years.)
>> 
>> My speculation is that, within the broadcast community, this technique
>> is well known.  But outside that, most people are working off the
>> description from the FCC regulations, which is the frequency domain
>> description.  (Since they are more interested in bandwidth and 
>> interference than simple design.)
>> 
>> So you end up with things like the North Country Radio/Graf and Sheets
>> transmitter (Radio-Electronics March and April 1988) which used a
>> balanced modulator for the 38 kHz subcarrier and was overly complex.
>> And didn't work well, according to a friend who built one.
>> (Which makes sense, keeping your phase responses right through all
>> that would be hard.)
>> 
>> Mark Zenier  markz@ssc.wa.com  
>> 
>Speaking of old tuners, can anyone lend some insight into the historic 
>Marantz 7B tuner which came out in about 1966??? It is still
>regarded as one of the finest FM tuners made!!! A few years back, I go a bunch
>of Marantz equipment from an estate sale. Aside from the fact that it uses
>tubes and had a totally cool oscilloscope built into it, what made this tuner 
>have such fantastic sensitivity and sound???? Is it possible to obtain a 
>schematic and build a tuner with more modern components??

Check Sam's Audio facts, you probably find something. Sam has 1-800-number,
but I do not remember off hand. Call 1-800-555-1212 and ask for their 
1-800-number.

                 With highest regards,
                      Babak   Sehari.
-- 
        "Giving power and money to the governments is like giving 
         whiskey and car keys to teenage boys."  
		                                  - P.J. O'Rourke

-- 
        "Giving power and money to the governments is like giving 
         whiskey and car keys to teenage boys."  
		                                  - P.J. O'Rourke

Newsgroups: sci.electronics,comp.robotics