I am a former Foreign Service Officer.

I have a certain amount of first hand, and a larger amount of 2nd hand knowledge about the thing, having worked for a couple of years in the early 1960s in the organization that was responsible for dealing with it and all similar problems – the division of technical services of the office of security of the department of state: abbreviated as O:SY/T.

I knew the tech who actually discovered the thing (slightly), and heard from him in detail exactly how he found it. Some of your published accounts are a little inaccurate, but not essentially so.

It was found using a basically untuned crystal video receiver, so we did not know what the activating frequency was. Much more sophisticated tech surveillance countermeasures receivers came into use later.

In the early 1960s the device and the great seal were both on display in SY’s little conference room – the room used for briefing people on technical surveillance countermeasures problems, and I got to handle and inspect them both many times. I also studied the various reports on how it functioned, prepared by several US Government labs and contractors. I also got to see and study various US government versions and developments from the thing.

The State Department’s overseas facilities were very high priority and highly vulnerable targets for Soviet-bloc intelligence, so we got to experience, so to speak, many more and much more interesting tech surveillance attacks than other parts of the US government. The recognition of this fact led to the launching of a very serious science-based tech surveillance countermeasures effort.

We did get launched, to a significant extent, by the Brits, but that is more a 1950s than a 1960s story.

The bald gent shown in your photo with Mr. (John) Reilly is Bud Hill, the then director of SY/T, my boss in the early 1960s. A first-rate scientist, although he tended to depreciate that and describe himself as being ‘only an electrical engineer’. His hiring by the Department of State marked the beginning of a serious American scientific response to tech surveillance countermeasures.

The great seal device was inherently resonate at multiples of a particular frequency, and this gave rise to a certain amount of confusion (in some places) about the frequency of the signal that activated it. As a consequence of its extreme simplicity it also inherently created both AM and FM modulation, so there was again some confusion about the character of the surveillance receiver. It was probably a straightforward zero-IF receiver that delivered the amplitude modulation of the re-emitted signal as audio output.

TSCM History – The Great Seal Bug Story – Part I – Cutaway diagram of “The Thing” bugging device from Scientific American magazine.

A drawing and description of the device was published in Scientific American sometime in the 1960s or early 1970s – in connection, if I recall correctly, with the amateur scientist column. I was, to say the least, surprised to see it. It was very accurate. (left)

The carved space within the seal indicated that the device found was a later generation device – the earlier one(s) had been bigger. And the Soviets much have changed them out from time to time, as improvements were made.

Our inspect-able transparent room-within-a-room acoustically secure conference rooms were one response to tech surveillance problems. I was in charge of that program for a while. They have been widely discussed elsewhere – and were shown off by the Iranians, so they are not so secret, and I have nothing to add about them.

O:SY/T had several early significant successes, due to a combination of new science, more scientifically trained people, greater cooperation from other agencies, etc..

During my service in O:SY/T we pulled a huge wired microphone array out of the embassy in Moscow. 57 of them, if I recall. The event was described in the NY Times at some length.

Someone should do a complete and science-based account of “The Moscow Signal”; a technical surveillance story that continued through the 1960s and after. It is, I think, a much more interesting story than that of the Great Seal device, and it very likely had its origins in the same organization. They are both ‘spy beam’ stories.

You have not mentioned many of the individuals who were important to the US scientific response to soviet tech surveillance, but I do not feel able to or entitled to present the fuller story. Other than to note that I feel that the driving intellectual force behind this was the Department of State, and not the CIA or some part of the Department of Defense. I have noted a tendency by some to rewrite history about this.

You might want to follow up on the events connected to the departure of Otto Otepka. His presence in the Department of State as a spy for the McCarthy people in congress – after McCarthy’s departure – did the Department of State and especially its Office of Security great harm. The ‘events’ (see the NY Times) resulted in both Reiley’s and Hill’s forced departures.

My last acts in that unfortunate drama were to urge, in a meeting with associates from CIA, NSA and other agencies, that some attempt be made to shift some of SY/T’s TEMPEST-related activities out of State and more into the direct management of my organization’s natural organizational competitors – the CIA…

I have just stumbled over the Scientific American article that I mentioned.

The description and drawing in Scientific American appeared in March 1968 at pages 132-133. The drawing is very accurate, but is not accompanied by much description. For example, it shows, but not mention, that the pedestal face adjacent to the diaphragm is not smooth. It had, if I recall, machined grooves and machined radial lines, presumably to reduce any air cushion effect as the diaphragm vibrated.

The pedestal and diaphragm together made up a sort of air-variable capacitor, which altered the resonant behavior of the cavity.

I do not recall there being any vent holes designed to avoid an air-cushion effect; I question any description that says that there were some.

The story of how we couldn’t figure it out, and that we relied on the Brits to tell us how it worked is, to say the least, an exaggeration.

It was studied by some of our premier scientific establishments, and well understood by them. If I recall correctly, The Navel Research Lab [sic] (a not sufficiently known body), Bell Labs, and a special commission put together by the National Academy of Science all looked at it – I remember being quite impressed by some of the studies. They addressed both the device itself and some very significant improvements that could be made to it.

Some research turned up quite old French and German patents and other publications that could have inspired the device, The French had a communication system for taxicabs that operated on a somewhat similar principle – a super-regenerative transponder that only ‘came on’ (emitted a modulated signal) when the central station sent out a query signal that pushed the local oscillator into action.

Our aim was to greatly increase the Q, so that it would not respond to any old source, but only to one of a specific frequency. Increasing the Q also increased the modulation, effectively increasing the maximum distance between the power source and the device.

The diaphragm excursion was, if I recall correctly, very small. The diaphragm was quite delicate. I think that a military lab that played around with it found that out to their sorrow.

Later models had a much more complex interior structure – one had a helical member, instead of a post – supporting the non-moving plate of the ‘variable capacitor’. Probably part of the effort to increase the Q. I recall seeing US versions with dipole rather than monopole antennas. And I know that the Germans also worked up advanced versions of their own.

Battery operated bugs that could be switched on and off remotely were and are pretty common.

Great Seal-like devices were eventually entirely superseded (at least in high-threat environments) by devices that were powered by radiate energy that stored that energy and that could be switched on and off without regard to whether the power source was active or not.

But more primitive Great-Seal like devices devices that did not store energy continued to be used by major powers in third world countries for years.

The development of systems that stored radiated power and that could be switched on and off remotely, and other information, tended to make some of us believe that the Moscow Signal was not a radio-biological weapon at all, but rather part of an evolved bugging system.

All this soon led to devices that drew their power from strong rf fields that were ‘naturally present’, like those arising from local TV transmitting stations, and that could also be switched on and off remotely – by very subtle and hard to detect signals.

As detection systems improved, the bugs also evolved, returning signals with modulation schemes (eg spread spectrum) designed to avoid quick and easy discovery – at least by the counter-surveillance receivers of the day.

The evolution was intended, of course, to eliminate the ability to detect Great-seal type devices by simply illuminating the bugged area with a swept frequency transmitter and looking for an AM or FM modulated return of the frequency being used. I notice that even today some venders of bug-detection systems have never progressed past this point.

Later on, devices that stored collected data and delivered it in well-hidden bursts, on command, came into use.

I know of nothing that indicates that the Soviets were using that technology for these purposes in the early 1960s. The recording devices in use back then were simply too bulky, power-consuming and unreliable. Consider the failures of such devices in the early era of space satellites and undersea and underground cable tapping ventures.

I believe that everything that I have mentioned here is both long-since public knowledge, if not actually declassified, as well as being very old technology – as I have not been in the business in any way for almost fifty (!) years.

Thank you for sharing your most interesting and illuminating contribution to the history of The Great Seal Bug. ~Kevin