[Premium-Rx] Stereo

[Peter Gottlieb]

Interesting.

My understanding is the 21.4 MHz IF was chosen for higher bandwidth demodulation 
in mind.  I just picked up some 8640 gear which apparently has a 10 MHz IF, 
completely non-standard.  So who knows what Mr. Grimm chose for those receivers; 
any of those IFs would work.

Peter


On 12/12/2016 8:30 AM, Terry O' wrote:
> I was given a butchered WJ receiver that contained a stereo demultiplexer.  I 
> have never revived this radio to see if it works.  The idea is great, but in 
> this radio, the mods done to the original IF and audio stages are appalling.
>
> During the CEI years, Ralph Grimm designed a stereo tuner and amplifier pair 
> that was manufactured in the 6006 Executive Blvd plant.  I have pictures of 
> dozens of these units under construction and testing.  They were never sold.  
> They were given away by Grimm.
>
> He also made the schematics available to employees and I have spoken to a 
> couple who used them to build copies of these units for themselves.
>
> This equipment and documents are extremely rare.  I hope to see examples of 
> them some day.  It would be interesting to see if Grimm used in house and 
> readily available 21.4 MHz IFs or designed his own 10.7 MHz circuitry.  He was 
> so much of a perfectionist that I am relatively certain these units are not 
> populated with circuitry made anywhere else.
>
> Terry O'
> http://Watkins-Johnson.terryo.org
> http://BlackRadios.terryo.org
>
>
> On 12/10/2016 7:21 PM, Peter Ratuschni wrote:
>> Hello Peter,
>> nice idea! I used to take the LF signal from the video out of a wj 8730A to 
>> feed the mpx circuit of a slightly modified FM tuner. (The 8730's audio 
>> output is to much lowpass filtered to contain any stereo information.)
>> best regards
>> Peter
>>
>
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