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

Wed May 30 11:37:13 EDT 2018

Hi All!
While I respect Terry's knowledge because he has spent a lot of time researching WJ, the impression reported back from the group after this email (below) is that the 8940 system is not useful as a manual receiver. 

It has the large plasma display which allows access via the keyboards to all the parameters. Much like any menu driven machine today. I think the early users of the system were more used to all of the knobs, buttons and switches of the typical manual receivers of the day.

The fact that it was controllable over IEEE-488 bus facilitated automatic search system implementation which was a boon in man-hour loading issues.

Hope this clarifies things a bit. Being able to automatically record signals above a threshold and compile lists of frequencies, amplitudes, etc. was a great benefit.
I contend that the departure from the manual receiver archetype to the computer controllable version was difficult for the older operators, having to learn a new paradigm of operation.  Now, it is a typical system.  Just like the old guys who liked their Simpson 260 and would not use Fluke DVM's.

WJ was truly notable for not "re-inventing the wheel". If they had an assembly, an IF, an SDU, audio board, power supply card, a demod system etc. they would incorporate as much of it as needed, whole modules, etc. into a new design. Very cost effective.  This lasted pretty well up to the point of the mini-ceptor era, when SMT technology changed the rules.  Maybe even the 8615 was beyond the edge of the previous system implementation rules, as there is little module commonality going backwards. 
The 8940 was no exception in that the design effort from it spawned a lot of electronic tuned assemblies, just as its preselectors found heritage from the varactor tuned designs of the 205 manual wideband intercept system.

I have most of the White Electronics automatic receiving system which was the first of its kind, all highly modified CEI/WJ stuff from the strictly manual era, really something with its motor driven tuners and limit set pots for sector scan. Output was on a pen plotter like an HP 135.
 I have several 205 systems and I think I still have the computer controllable card cage for the tuners. After all of this comes the WJ-8940.

I loved this stuff and collected up quite a pile. I still have around 800 individual pieces down from my peak of 1300 or so. When I got the chance to move from Nems, DEI, GEC ACL stuff to WJ, I jumped in!   I used to have a mountain of the old telemetry receivers, started collecting 39 years ago now. WJ was one hell of a company.
Starting with travelling wave tubes, they built themselves up into a truly vertically integrated concern. Raw materials became RF parts that were built into boxes that were integrated into systems.
A footnote: I still have a pile of gear painted "Royal Persian Blue" made for the Shaw of Iran before the country flipped over to the Ayatollahs.

73
Jeff Kruth

In a message dated 5/25/2018 1:54:20 AM Eastern Standard Time, Watkins-johnson at terryo.org writes:

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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