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W-J CEI CIA
The device is housed in a heavy 3U 19" rackmountable enclosure.
It covers all frequencies between 30 MHz and 1 GHz and is suitable for
the reception of AM, FM and CW radio signals.
The device has four individual tuners, one for each band: (1) 30-60 MHz,
(2) 60-300 MHz, (3) 235-500 MHz and (4) 490-1000 MHz. It has 3
selectable bandwidths at 20, 75 and 300 kHz, plus a 2 MHz wideband output
for monitoring and external demodulation. A built-in cathode ray
tube (CRT) is used as a panorama viewer, and shows 0 to 3 MHz of the
current spectrum.
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The first version of the RS-111 was introduced in 1963 by the original
manufacturer CEI in Bethesda (MD, USA). Initially developed as a
monitoring receiver for the US Department of Defense (DoD),
it also became a beloved surveillance receiver for the intelligence and
law enforcement community.
One of the most prominent users of the RS-111 was the US
Central Intelligence Agency (CIA), where it was
typically used for the reception of
covert listening devices (bugs).
When CEI was taken over by Watkins-Johnson (W-J)
in 1967, the RS-111 remained in production until 1980.
In total, well over 1000 units were manufactured. Over the years,
the device was updated and modified a number of times, and special
variants were made for specific customers. The version/variant number
is added as a suffix to the model number, e.g.: RS-111-1B-12A for version
12A of 1968.
According to one source, there were 105 variants of the device [2].
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All controls of the RS-111-1B are at the font panel of the device, as
shown in the image below. According to former users, the RS-111 was a
dream to operate. The front panel has an elegant layout and the controls
are grouped logically. The lower half holds the individual tuning controls
of each of the four frequency bands. The 4-position band selector is
located at the far right.
At the upper half is the panorama display which comprises a 1 x 2"
green Cathode Ray Tube (CRT) and several controls. The CRT displays part
of the frequency spectrum around the currently selected frequency.
At the centre is the IF bandwidth selector, and the adjustment of
the Beat Frequency Oscillator (BFO). Towards the right is the
MODE selector and the AF volume control. At the far right is the
signal strength indicator. On older versions this was a tuning indicator. 1
All connections, with exception of the 6 mm jack socket for the headphones,
are located at the rear panel, as shown in the image above. Two separate
antenna inputs are available (J1, J2) for the 30-500 and 490-1000 MHz
frequency ranges respectively. There are several outputs for the IF,
local oscillators, and various narrow- and wideband video signals.
At the bottom left is the fixed mains power cord, plus the mains voltage
selector with a fuse at either side. The leftmost fuse is only used when
115V AC is selected, whilst the rightmost one is only used for 230V AC.
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From version RS-111-1B-12 onwards, the tuning indicator is replaced
by a signal strength meter. For tuning, the new CRT display marker
should be used. This feature is also added on version RS-111-1B-12.
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Watergate Scandal
1972-1974
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The RS-111 played an important role during the Watergate scandal (1972-1974),
which eventually led to the resignation of US President Nixon in 1974 [3].
As part of the Republican campaign for Nixons re-election, a group known as
'The Plumbers' broke into the Watergate offices of their political opponents
– the Democratic Party – to photograph documents and plant telephone bugs.
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One of the people working for the
Committee for the re-election of the President, was James W. McCord Jr.,
an experienced former CIA operative, who knew his way around bugs
and associated equipment, and knew where to get them.
A wireless telephone bug, that could be planted inside a telephone set, was obtained
from Bell & Howell. Such a device was also know as a KEL-device, named after
the company that originally developed it. Although Bell & Howell also manufactured
a portable receiver for such a bug, with a built-in recorder, McCord choose a
Watkins-Johnson RS-111, probably because it was much more sensitive.
It allowed the bug to reach the room he had booked in a hotel across the street.
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The image above shows McCord –
during the congressional hearing before the Senate Watergate Committee on
22 May 1973. In his hand he holds the Bell & Howell bug that was planted in one
of the telephones.
At the left is the RS-111 used for the reception of the bug at 118.9 MHz.
He used his contacts as a former CIA operative to purchase a sales demo unit directly from the CEI division of Watkins-Johnson in Rockville (MD,
USA), for a much reduced price, paying in cash.
The delivery note above reveals that the deal took place on 12 May 1972,
and that McCord payed just USD 3500 — about half the official price —
for the RS-111-1B-12 with serial number 132.
The official sales invoice
was sent a few days later, on 15 May 1972, along with the manual [5].
➤ Sales invoice
➤ Full story by Terry O-Laughlin
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This short 44 sec. video clip presents the RS-111 in our collection,
minutes after it was restored on 17 July 2025. For the demonstration,
band 2 was selected (30-300 MHz), and the device was tuned to a local radio
station in the FM broadcast band.
The modulated signal from the radio station can be seen on the panorama
viewer at the top left, which can also be used as a tuning aid.
Source
Crypto Museum, 17 July 2025
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Below is the simplified block diagram of the RS-111. At the left are
four RF tuners that together cover the entire 30-1000 MHz range.
There are two mixer paths: one for the 30-300 MHz range, and one for the
235-1000 MHz range. The former is directly converted to 21.4 MHz,
whilst the latter is first converted to 60 MHz and then to 21.4 MHz.
At the centre is the IF strip, which is in reality much more complex
than the block diagram suggests. It provides several output signals.
The WB/IF section provides wideband
AM Video and FM Video outputs with a 2 MHz bandwidth.
These signals are intended for monitoring
and for external demodulators that can process subcarrier
(double-modulated) signals.
The output from the NB/IF unit (see below)
is fed to the FM discriminator
and AM detector, each of which can be selected for the Audio and
Video outputs. The AM detector also drives the Automatic Gain Control
(AGC) and signal strength indicator.
The diagram below shows a more detailed block diagram of the RF tuners.
Each tuner consists of an adjustable bandpass filter, an amplifier and
another bandpass filter, followed by a mixer. The amplifier gain is controlled
by the AGC. Furthermore, each tuner has its own Local Oscillator (LO).
The mixer produces an IF signal at 21.4 MHz, or in the case of the lower two
tuners, 60 MHz which then converted down to 21.4 MHz in another mixer.
The 490-1000 MHz tuner is built with stripline technology.
The narrowband IF unit (NB/IF), consists in reality of three sections:
Each of the three IF sections (300 kHz, 75 kHz and 20 kHz) consists of an
amplifier, a bandpass filter and another amplifier. The gain of each
amplifier is controlled by the AGC signal. Note that the inputs and
outputs of the three IF section are connected in parallel. The desired
bandwidth is selected by applying the AGC signal. This biasses the
transistors in the selected IF-amplifier stages. If no AGC signal is
applied, the corresponding amplifiers are automatically disabled.
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Accessing the interior of the RS-111 is simple. The device is housed
in a 3U 19" rackmountable enclosure that consists of a welded aluminium frame
with a sub-frame that devides the case in an upper and a lower half. At the
top and bottom are removable perforated panels that are held in place by 14
click-screws each. After turning all click-screws 90° counter clockwise,
the panels can be removed, after which the interior becomes accessible
as shown in the images below.
The image above shows the upper half of the chassis, which comprises the
power supply unit (PSU), the tuning sections for each of the four bands, and
the IF-strip that is responsible for demodulation of the regular
waveforms (AM, FM, CW).
Below the IF-strip is another IF-strip
that provides the video outputs.
At the left end is the cathode ray tube (CRT) that is part of the
panorama viewer. The accompanying electronics are housed in a separate
sub-unit that is hinged-up in the image above.
Note that many of the sub-units are gold-plated to optimise RF shielding.
The image above shows the lower half of the chassis, which comprises the
individual band tuners and most of the wiring. From the date codes on the
capacitors we were able to deduce that the device shown here was probably
manufactured in late 1979 or early 1980. This means that it belongs to one
of the last production batches of this device, as it was discontinued in 1980.
Note that many parts of this radio were produced in-house at the Watkins-Johnson
(CEI) facility in Rockville (Maryland, USA).
The enclosures were made from aluminium stock and were cut,
perforated, bended and welded in-house.
The mains transformer and the tuning gears were fully made at the production
site, and
even the gold-plating of the sub-assemblies was done in-house [1].
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When we received the RS-111 in our collection in December 2022, it was
defective. Furthermore, the quality of the power cord was doubtful
and the exterior had collected dust for quite a few years. Apparently, the
previous owner had already started an attempt to repair the device, as the
wiring around the mains power transformer had been soldered on. The transformer
has two primary windings that can be connected in series (230V) or parallel
(115V) by means of the voltage selector at the rear. It was decided to
remove the voltage selector and wire the transformer permanently for 230V
only. At the same time the power cord was replaced by a neoprene one.
This was enough to bring the receiver to life again. The scale lamp of one
of the four band tuners was replaced, and both the interior and exterior were
cleaned thoroughly. When inspecting the interior, it was noticed that the
device had been modified. BNC sockets had been added at either side of the
screw terminal block at the rear panel,
and a DYMO label had been added to describe their function as
pulse stretcher.
The BNC sockets and the screw terminal block were wired to an improvised
homemade PCB with an isolated circuit that was fitted somewhere in a corner.
We removed the PCB and the two BNC sockets, and restored the original
wiring of the screw terminals.
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A part that needed special attention is the
tuning gear, which is located
directly behind the front panel. Operating the tuning dials was quite noisy
and was not very smooth. The cogwheels were cleaned and oiled, but the
biggest challenge appeared to be the planetary gear [4] that is fitted
directly to the axle of each of each tuning dial.
As the planetary gear 1 is a closed construction it is difficult to apply oil
to it. This was solved by removing the tuning knobs and applying oil directly
to the axle, whilst continuously turning it. The tuning gear is now smooth
and silent again.
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As the mains power in continental Europe often exceeds 230V nowadays —
in some cases it is as high as 245V — whilst the transformer is made for 230V,
it was decided to connect
two 22Ω/5W resistors in series 2 with the
primairy winding. This reduces the primary voltage somewhat, and prevents the
transformer from saturating and running hot. The device was then
tested with live signals
on each of the four frequency bands.
Amazingly, the receiver was still within its specifications and no further
alignment was needed, more than 45 years 3 after it was manufacturered.
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Also known as an epicyclic gearing [4].
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One resistor in series with the LIVE wire (brown) and one in series with
the NULL wire (blue).
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From the date codes on some of the components, we estimated that the
device shown here was built in late 1979 or early 1980, which means that
it was produced in one of the last batches (1963-1980).
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Completely dead Exterior dusty and dirty Tuning gear stiff and noisy
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- Exterior thoroughly cleaned
- Interior thoroughly cleaned
- Mains wiring corrected and modified
- Mains power cord replaced
- 115/230V voltage selector removed (now wired permanently for 230V only)
- Two resistors connected in series with the primary side to lower the mains voltage
- Scale lamp replaced
- Unrelated PCB with pulse stretcher removed
- IF-wiring restored (was modified by previous owner)
- Two BNC sockets at rear panel removed
- Wiring of 600Ω audio line out restored (screw terminals)
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Device VHF/UHF surveillance receiver Purpose Surveillance and radio monitoring Model RS-111 Manufacturer CEI (until 1967), Watkins-Johnson (from 1967) Designator AN/URR-52 Year 1963 Country USA Production 1963-1980 (17 years) Frequency 30-1000 MHz Bands 4 (see below) Waveforms AM, FM, CW Bandwidth 20, 75, 300 kHz, 2 MHz (video) Power 115/230 V AC, 50-400 Hz Dimensions 483 × 400 × 134 mm Weight 16 kg Quantity > 1000 Price US$ 6,250 (1968) [A]
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| | Civil | Military | Year | Description |
| | RS-111-1B-7 | AN/URR-52A | 1963 | First core version of the RS-111 |
| | RS-111-1B-12 | AN/URR-52B | 1968 | Second core version of the RS-111 |
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- 30-60 MHz
- 60-300 MHz
- 235-500 MHz
- 490-1000 MHz
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Below is a non-exhaustive list of known production variants:
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- 1963
- Modified version of the RS-111-1B, with:
- Internal relays controlled from front panel, providing AM/FM video output
- Single antenna for entire frequency range
- AGC monitor
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- 1968
- Second core version of the RS-111-1B
- New 3ASP1 CRT (instead of 2XP1)
- New panarama viewer electronics with switchable 21.4 MHz marker and improved linearity
- Additional unamplified AM video output
- Signal strength meter (instead of tuning indicator)
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- 1974
- Same as RS-111-1B-12, but with:
- Digital Automatic Frequency Control (DAFC)
- Provision for external 6-digit frequency readout 1
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Compatible frequency counters are DRO-309A and DRO-333.
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- RS-111-1B-7 datasheet 1
CEI, Rockville (MD, USA). 5 April 1968.
- RS-111-1B-12 datasheet 1
CEI, Rockville (MD, USA). 5 April 1968.
- RS-111-1B-12B datasheet
Watkins-Johnson, Gaithersburg (MD, USA). December 1974.
- RS-111-1B-2 instruction manual
CEI, Rockville (MD, USA). 30 November 1965. 1
- RS-111-1B-7 (AN/URR-52A) technical manual
This manual covers all versions from the first couple of years.
Watkins-Johnson Company CEI Division, Rockville (MD, USA). 16 April 1973. 1
- RS-111-1B-12A technical manual
This manual covers all versions from 12 onwards.
Watkins-Johnson Company , Gaithersburg (MD, USA). 5 June 1974. 1
- RS-111-1B-17 supplement
Watkins-Johnson Company CEI Division, Rockville (MD, USA). 15 July 1971. 1
- RS-111-1B-26 supplement
Watkins-Johnson Company CEI Division, Rockville (MD, USA). 17 September 1970. 1
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© Crypto Museum. Created: Monday 12 December 2022. Last changed: Sunday, 17 August 2025 - 20:31 CET.
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![Delivery note issued by Watkins-Johnson to James McCord on 12 May 1972. Click to see the full document [5].](img/WJ_delivery.jpg)
