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MSR-903 →
Portable microwave surveillance receiver · 1-26 GHz - under construction

MSR-902 is a mobile precision UHF/SHF surveillance receiver for signals in the 1-18 GHz band, expandable to 18-26 GHz, developed around 1989 by Micro-Tel Corporation in Hunt Valley (MD, US). It was intended for mobile interception and for locating covert listening devices (bugs).

Like its predecessor, the MSR-901, the device is usually housed in standard Samsonite briefcase or — as shown in the image on the right — in a larger Samsonite suitcase, along with one or two tuners that cover the entire 1-26 GHz range.

The actual receiver has a rectanglular shape and is painted in the typical Micro-Tel mint colour. The control panel is at the top, which allows operation from within a briefcase. When present, the tuners are fitted in the remaing space of the supporting frame. Any cables and accessories are stored in the top lid of the Samsonite case.
MSR-902C main unit


MSR-902C main unit
Original MSR-902 with built-in tuners and battery, photograph via eBay [2]
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MSR-902C main unit
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Original MSR-902 with built-in tuners and battery, photograph via eBay [2]

The following versions of the MSR-902 are currently known:

  • MSR-902
    This is the initial version of the MSR-902 as it was released in the mid-1980s. It is an all-in-one unit that has a frequency coverage of 1-18 GHz. Antenna inputs are at the front right of the control panel. There are three N-type sockets for: (1) 1-12 GHz antenna, (2) 12-18 GHz antenna and (3) External mixer. The version is usually housed in a standard Samsonite briefcase, much like its predecessor, the 1-12 GHz MSR-901.  Photograph

  • MSR-902C
    This is the version that is featured on this page. It has no built-in tuners, but fully relies on two external tuners: a large one for the 1-18 GHz range, and a smaller one for 18-26 GHz. For this reason, the set is housed inside a larger Samsonite suitcase.
Controls   MSR-902C
The diagram below sbows the top panel of the MSR-902C, which is slightly different from the MSR-902. The upper 2/3 holds the sockets for connection of the power sources and the two tuners, whilst the lower 1/3 holds the control panel, with the large two-speed tuning dial at the centre. Above the tuning dial are the frequency readout, the band selector and a tuning indicator. At the bottom left is the POWER switch (ON/OFF), whilst the mains should be connected to the EURO-receptacle at the top. Ensure that the correct voltage is selected before turning it on.

Click to see more

To the left of the tuning dial are the controls for selection the bandwidth and operating the internal scanning features. The big dial at the far left is for selecting the width of the sweeping range. The sockets at the the top left are for connection of an oscilloscope, that can be used as a panoramic display. There are also two sockets for the IF outputs (250 MHz and 21.4 MHz). To the right of the frequency dial are the demodulator and output controls. On the earlier MSR-902, the empty section at the right holds the two antenna inputs for the 1-18 GHz and 18-26 GHz ranges. They are omitted on the MSR-902A, as on that version the antennas are connected to the tuners.

Block diagram
The diagram below shows the configuration for two known versions of the MSR-902. At the left is the initial version, in which the tuner is housed inside the main device. The tuner has two inputs: one for each range (1-12 GHZ and 12-18 GHz). At the right is the MSR-902C that is featured on this page. It has two separate tuners that are fitted externally: one for the initial 1-18 GHz range, divided over two sub-ranges with separate inputs, and an optional one for the 18-26 GHz range.


Samsonite briefcase
Larger Samsonite suitcase
MSR-902C main unit
1-18 GHz tuner
Interconnecting cables
Suitable antennas
Operating instructions and service manual
The initial version of the MSR-902 was usually housed inside a standard Samsonite briefcase of the era, much like its predecessor the MSR-901.   
Samsonite briefcase with Micro-Tel MSR-901

With the MSR-902C, the two tuners are fitted externally, which means that the standard Samsonite briefcase shown above, is not large enough. For this reason, the MSR-902C was fitted inside a larger Samsonite travel suitcase, such as the one shown in the image on the right.   

The actual receiver can be recognised by its typical main colour, and is usually fitted in the bottom section of the briefcase. All controls and connections are located at the top surface. The receiver is also known as the main unit.

With the MSR-902, the tuners are fitted internally and their inputs are located at the front right of the control panel. With the MSR-902C, the tuners are fitted externally and are connected to the receiver via a set of cables.
MSR-902C main unit

Tuner 1   1-18 GHz
This tuner is for reception of the 1-18 GHz range and is the largest of the two tuners that can be fitted to the MSR-902C. It is commonly mounted to the right of the main unit and is connected to it via a short coaxial cable (IF) and a thick multi-wire cable (control).

The tuner has two inputs: one for the 1-12.6 GHz range and one for the 12.6-18 GHz range. The output is delivered to the main unit via a single short IF cable.

 Look inside

Tuner (1): 1-18 GHz

Tuner 2
Optionally, a second tuner can be fitted for the 18-26 GHz range. It is much smaller than the 1-18 GHz one, and is usually fitted behind the main unit. Like tuner 1, it is connected to the main unit by means of a coaxial cable (IF) and a (thick) control cable.

 Look inside


With the MSR-902C, the two tuners are fitted externally, which means that they will hvae to connected to the main unit. At both tuners contain electronically adjustable YIG filters, a rather thick control cable is needed between the tuners and the main unit. The output of each tuner is delivered via a short coaxial cable.

Control cables for the MSR-902 are extremely rare. They are available in two variants: short and long. The short ones are used when the unit is installed in a Samsonite case, whilst the long ones are for detached use and maintenance.

Cables for connecting the tuners

The difficulty with an UHF/SHF receiver like the MSR-902, is finding one or more antennas that are suitable for the extremely high frequencies and the wide band coverage. Although it is not possible to find a single antenna that covers the entire frequency range, it should be possible to find antennas that cover the individual bands that are supported by the external converters.

The image on the right shows a very rare Dyson dual element conical spiral antenna that is suitable for the 1-12 GHz frequency range.

 More information

Conical spiral antenna 1-10 GHz

Manuals   wanted
The MSR-902 was supplied with an Operating and Instructions Manual and (optionally) with a full Service Manual that contains detailed circuit descriptions and diagrams.

Unfortunately, neither of these manuals is currently available to us. If you have any of these manuals, we would be very pleased to receive a copy or a scan.

 Contact us


Receiver main unit

Tuner 1

Tuner 2

... broken YIG oscillator ...

As with most complex devices that are more than 30 years old, it may be necessary to carry out a few repairs in order to bring it back to life. With the MSR-902C featured on this page, this was no different. In this particular case, most of the repairs, and hence the restoration, was carried out by the previous owner, Dr. Simon Schrödle in Germany, who has described the repair in great detail on his excellent web blog: Simons Dialogs [1]. Among other things, he did the following:

  • Dead PSU repaired (broken MJ12002 transistor)
  • A3B5 and A3B6 boards repaired (broken 7401, 7404, transistor and LEDs)
  • Filter properly mounted (caused short-circuit on the +15V rail)
  • Frequency readout fixed (broken reference diode)
  • Research broken YIG oscillator in 18-26 GHz tuner (not fixed) [2]
  • Frequency
    1-18 GHz, extendable to 100 GHz using external harmonic mixers
  • Noise
    20dB 1 1-18 GHz
  • Readout
    4-digit LED display, accuracy ±1%, +1 digit
  • Tuning
  • Modes
     see tuning modes
  • Preselection
    Auto-tracked 3-section YIG filter in all tuning modes
  • Indicator
    Uncalibrated signallevel meter
  • AFC
    10:1 correction
  • Ant. conduction
    <-70dBm, +60dBm above 12 GHz
  • RFI
    Fully RFI protected
  • Image rejection
    >70dB, 60dB above 12 GHz
  • IF rejection
  • RF inputs
    Type N, 50Ω nominal
  • IF gain control
    60dB range
  • IF bandwidths
    0.1, 1, 20 MHz (linear) 2
  • IF output
    10 MHz bandw. at 250 MHz, ≤-6dBm at 50Ω, 14dB gain from mixer
  • Demodulator
    AM, FM
  • Audio
    5.0 mW 600Ω, phone jack, variable gain
  • Sweep rate
    0.1 - 30 Hz (variable)
  • Oscilloscope
    Hor: 3Vpp DC 1000&Omega. Blanking: +5V pulse at 5000Ω
  • Power
    115/230VAC, 50-400Hz, 75W / +12V DC, 50W
  • Size
    Attache case: 17 x 12 x 5 inches
  • Weight
    35 pounds
  1. Typical over 90% of the band. Add 3db for maximum noise figure.
  2. Other linear bandwidths available on special order (0.1-20 MHz). 10 MHz Log IF available.

Frequency ranges
  1. 1-12.6 GHz
  2. 12-18 GHz
  3. 18-26 GHz
Tuning modes
  • Scan
    Full band sweep at variable rate with manually tuned frequency marker
  • Var Scan
    Variable 0 to ±5% sweep around center frequency
  • Man
    Dual-speed control of frequency, with veneer
  • 1
    MSR-902 receiver (main unit)
  • 2
    Provision for external harmonic mixers 18-100 GHz
  • 2A
    Provision plus external mixers 18-40 GHz
  • 3
    Log IF Amplifier - 10 MHz bandwidth 1
  • 4
    21.4 MHz IF output 2
  • 5
    Additional IF bandwidth 1
  1. Options 3 and 5 are not available together.
  2. Option 4 can be installed only if internal battery is not fitted. +12V DC external power capability is maintained.

  • VDA-60
    Video Display Analyzer
  • AK-902
    Accessory Kit
At present, the YiG oscillator of the 16-28 GHZ converter is broken. Crypto Museum are looking for a replacement YiG oscillator, and also for the full service manual and circuit diagrams of the MSR-902C. If you can supply any of the following items, please contact us:

  • YiG oscillator for 18-26 GHz tuner: Avantek S081-0321
  • MSR-902C user and service manual
  • Short control cable for 1-18 GHz tuner
  • AK-902 Accessory Kit
  1. MSR-902 briefcase portable microwave surveillance receiver (brochure)
    Micro-Tel (Adams-Russel). February 1989. 4 pages. 1
  1. Obtained via Terry O'Laughlin, Black Radios website.  More

  1. Simon Schrödle, Micro-Tel MSR-902C microwave surveillance receiver —
    A very intriguing 60 pound briefcase — Website: Simons Dialogs.
    6 May 2016 - 2 November 2016.

  2. Simon Schrödle, Avantek S081-0321 YIG oscillator — not oscillating at all
    Website: Simons Dialogs. 1 October 2016.

  3. Ebay user earthlytoys, Image of MSR-902
    19 May 2017. Retrieved October 2017.
Further information
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Crypto Museum. Created: Wednesday 18 October 2017. Last changed: Wednesday, 05 August 2020 - 07:13 CET.
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