Quad-FM: Panasonic RD-9610 Quadraphonic FM Demodulator

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Q-Eight

2K Club - QQ Super Nova
Since 2002/2003
Joined
Sep 30, 2003
Messages
3,712
Location
Castlegar, BC, Canada
Unfortunately, I was outbid with 1 second to go. Very little known about this unit and can find nothing online about it. But at the very least, we can now see what would have attached to that mysterious MPX OUT jack on the back of many of our receivers!! :cool:


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If you look up stuff on Lou Dorren, there's an anecdote about 100 pre-production units being made for field testing. However, the story doesn't go into detail exactly which Quad-FM system they were testing as there were other Quad-FM systems being field tested other than LD's Quadraplex. The only sure-fire way to tell was to get this machine, pop the cover off and inspect which IC chip it uses for decode. Quadraplex used a particular chip while I'm not sure the other systems did.

Hence why I was asking in another thread about how hard it would be to replicate the Quadraplex encoding. I was really hoping to see if I could make this little box do it's thing again.
 
Well, I didn't want to pay more than $70 for what is essentially, an inoperative piece of equipment. The auction had ZERO bids right up until near the end. I bid $70 with 8 seconds to go, and somebody else threw in a higher bid with 1 second left on the clock. But hey, that's life I guess. At least I've got the pictures to prove it's existence.
 
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That is Ultra Cool!

Just imagine being able to tune into an FM station and getting 4 discrete channels! It really is a shame it never came to be.

Doug
 
Well, I didn't want to pay more than $70 for what is essentially, an inoperative piece of equipment. The auction had ZERO bids right up until near the end. I bid $70 with 8 seconds to go, and somebody else threw in a higher bid with 1 second left on the clock. But hey, that's life I guess. At least I've got the pictures to prove it's existence.

You can set limits on how much you spend or want to pay. I'm sure that's what happened here. I used to try to get the last second in and never could, until I found the auto bid.
 
That is Ultra Cool!

Just imagine being able to tune into an FM station and getting 4 discrete channels! It really is a shame it never came to be.

Doug

Heck yeah!! I really wonder how well it works? They say it was the best system at the time. Too bad it wasn't a more impressive looking box with dials and adjustments and stuff to fiddle with! :D
 
I remember my Dad having to pay $75 extra for an FM (stereo) multiplex decoder. It was a black (actually gold) box that hooked to the back of the receiver.

Great article by Len Feldman. Many moons ago, I was at a seminar taught by Len Feldman. He asked us, "who knows what NTSC stands for?" I answered, "Never The Same Color!"
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Here's an old article about FM stereo MPX.
http://antiquesci.50webs.com/EI1959.htm
 
It was our good Dr Bose who opposed quad FM broadcasts and got his way.
From wiki:

In 1969 Louis Dorren invented the Quadraplex system of single station, discrete, compatible four-channel FM broadcasting. There are two additional subcarriers in the Quadraplex system, supplementing the single one used in standard stereo FM. The baseband layout is as follows:

50 Hz to 15 kHz Main Channel (sum of all 4 channels) (LF+LR+RF+RR) signal, for mono FM listening compatibility.
23 to 53 kHz (cosine quadrature subcarrier) (LF+LR) - (RF+RR) Left minus Right difference signal. This signal's modulation in algebraic sum and difference with the Main channel was used for 2 channel stereo listener compatibility.
23 to 53 kHz (sine quadrature 38 kHz subcarrier) (LF+RF) - (LR+RR) Front minus Back difference signal. This signal's modulation in algebraic sum and difference with the Main channel and all the other subcarriers is used for the Quadraphonic listener.
61 to 91 kHz (cosine quadrature 76 kHz subcarrier) (LF+RR) - (LR+RF) Diagonal difference signal. This signal's modulation in algebraic sum and difference with the main channel and all the other subcarriers is also used for the Quadraphonic listener.
95 kHz SCA subcarrier, phase-locked to 19 kHz pilot, for reading services for the blind, background music, etc.

There were several variations on this system submitted by GE, Zenith, RCA, and Denon for testing and consideration during the National Quadraphonic Radio Committee field trials for the FCC. The original Dorren Quadraplex System outperformed all the others and was chosen as the national standard for Quadraphonic FM broadcasting in the United States. The first commercial FM station to broadcast quadraphonic program content was WIQB (now called WWWW-FM) in Ann Arbor/Saline, Michigan under the guidance of Chief Engineer Brian Brown.
 
Hi Everyone,I was wondering how long FM broadcasting lasted in this country.when I was staitioned at shepperd AFB in Witchata Falls,Tex in 1972.The FM staition there said that in the evening they would be broadcasting in quadraphonic.this happened for the two and a half months that I was there.Maybe somone else on the forum might know about this. thank you all.
 
That is Ultra Cool!

Just imagine being able to tune into an FM station and getting 4 discrete channels! It really is a shame it never came to be.

Doug
When I listened to WBCN Boston it was broadcast in quad, matrix, the tapes I recorded are in quad
 
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