[Premium-Rx] WTB: Watkins Johnson 8940 Tempest Rx System

Sat May 26 02:23:00 EDT 2018

I rebuilt an 8999 with extender and some demod options.  It was
interesting to play with.  (Replaced all thr tantalums after two
successive failures damaged one power supply bus)  It is much more
intuitive than the 8940.  It was a great spectrum processor but not the
best receiver.  I sold the radio but still have a copy of the manual.

Terry O'

> The 8940 was replaced by the 8999.  The 8999, with the optional extender,
> goes up to 12.4GHz....
>
> Nice radio!
>
> -----Original Message-----
> From: premium-rx-bounces at mailman.qth.net
> [mailto:premium-rx-bounces at mailman.qth.net] On Behalf Of W2HX
> Sent: Friday, May 25, 2018 7:29 AM
> To: Watkins-johnson at terryo.org
> Cc: Premium-Rx at mailman.qth.net
> Subject: Re: [Premium-Rx] WTB: Watkins Johnson 8940 Tempest Rx System
>
> Fascinating. I would love to see a picture of this and know its basic
> details like frequency range.  My other hobby is ruining some PDP--11s so
> i
> wonder if this would be a cool system to acquire to combine two interests
> for me
>
> Eugene
>
> ________________________________________
> From: Watkins-johnson at terryo.org <Watkins-johnson at terryo.org>
> Sent: Friday, May 25, 2018 1:54 AM
> To: W2HX
> Cc: Jeff Kruth; ka2ivy at verizon.net; Premium-Rx at mailman.qth.net
> Subject: Re: [Premium-Rx] WTB: Watkins Johnson  8940 Tempest Rx System
>
> The 8940 is an interesting part of WJ history.  The first version was
> produced under extreme duress.  Based on interviews I've done it was
> pretty ineffectual, but satisfied the urgent contract under which it was
> developed.
>
> The A version, which was a major redesign, worked better.  It was designed
> to work with a PDP-11 but they weren't a smooth coupling.  A test engineer
> for GTE who used one extensively on crypto machines told me he had to
> reboot the PDP often because they would stop working together.  I had one
> of these with all the manuals and basically gave it away.  A lot of space
> and too much work for too little return.
>
> The B version worked out many of the kinks and expanded the capabilities.
> It worked well and was apparently well liked.  It still leaves a lot to be
> desired as a standalone receiver because it was also designed to be
> computer controlled.
>
> The TSU and some modules of the B version were redeveloped into another
> receiver system as part of a larger contract with Iran but was never
> delivered.  A multipoint monitoring system was also developed for Germany
> that was delivered.
>
> The 8940 was third wide spectrum analysis system that WJ developed.  The
> first two systems were even more cumbersome in size and operation.
>
> I have a lot of information on all of these systems and iterations. My
> websites are way behind my research because the digging is going so well
> that posting is way down the priority list.
>
> Terry O'
> http://Watkins-Johnson.terryo.org
> http://BlackRadios.terryo.org
>
>
>> Sounds fascinating. Where can one findany photos of such a system?
>> Google
>> didn't help.
>>
>> Sent from Nine<http://www.9folders.com/>
>> ________________________________
>> From: Jeff Kruth via Premium-Rx <premium-rx at mailman.qth.net>
>> Sent: Wednesday, May 23, 2018 4:35 AM
>> To: ka2ivy at verizon.net; Premium-Rx at mailman.qth.net
>> Subject: Re: [Premium-Rx] WTB: Watkins Johnson 8940 Tempest Rx System
>>
>> Hi Bruce!
>>
>>
>> I have two of them and would part with one.  They cost me a bit back in
>> the day. Complete system, desk and all, cables etc.  I may even have
>> some
>> documents for loan to copy. We can discuss the price. Shipping would be
>> by
>> freight or you could pick it up.  These were functional units when I
>> bought them, and have been in storage (in my lab) ever since. Never got
>> around to using them, so they have sat in the corner. Not many were
>> made,
>> and at one point WJ had a sale for one of mine to Denmark, as WJ did not
>> want to build a one-off. It was from this that I learned they were
>> $300K.
>> Did not come through. This was back just at the time the Clinton Admin
>> killed the Tempest requirement.
>> They are really quite the thing!
>>
>> 73
>> Jeff Kruth
>> WA3ZKR
>>
>> In a message dated 5/22/2018 8:29:15 PM Eastern Standard Time,
>> ka2ivy at verizon.net writes:
>>
>>
>> I happened upon a brochure for the Watkins-Johnson WJ-8940 receiver in
>>
>> the desk console. Has anyone seen one of these, and even more important,
>> does anyone have a project one they are willing to part with? It looks
>> like a neat rig, restoring one would be quite a project but that's the
>> kind of puzzle and challenge I would like.
>>
>>  Bruce Gentry, KA2IVY
>>
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>
>
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