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Micro-Tel ← MSR-903
Precision surveillance receiver
- under construction
MSR-904 is a precision VHF-SHF
surveillance receiver for signals between
30 MHz 1 and 18 GHz, optionally expandable 2 to 40 GHz, developed around
1982 by Micro-Tel in Huntsville (MD, USA). It succeeded
the MSR-903 receiver and was intended for interception
of microwave links, satellite downlinks, telemetry signals,
bugs, etc.
The MSR-904A is an enhanced version of the MSR-904.
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The receiver is housed in a 19" rackmountable enclosure with strong
grips and the front and at the rear. The well-organised control panel is
painted in the typical Micro-Tel mint colour.
Most functions are controlled by push-buttons rather than by rotatory
selectors, and a digital frequency readout is available at the right.
At the left is a small CRT that offers a panoramic view of the spectrum
around the selected frequency. Two fast-responding LED bars are used
as signal strength and tuning indicators. The frequency is set with the
large dual-speed dial at the right.
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Requires option (3).
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Requires option (8) and external FE-904 frequency extender.
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The diagram below shows the front panel of the MSR-904A, which is divided
into three sections: the panaramic display and the attenuator at the left,
the controls at the center and the tuning dial with frequency readout at
the right. The power switch is at the bottom left. A suitable pair of
headphones should be connected at the bottom right, where also the AM/FM
selection is located.
The MSR-904 is the first receiver that does not feature the typical rotary
selectors for band, bandwidth, scanning, etc. Instead, the functions are
selected by means of neatly arranged push-buttons with a built-in LED
indicator. The scanning mode is also selected with push-buttons, whilst
the scanning adjustments are made with the five knobs along the bottom edge.
All connections (except for the headphones) are at the rear side.
The AC mains should be connected to the 3-pin military socket to the right
of the fan. Select the appropriate mains voltage before connecting the
receiver to the mains.
At the top left are the two antenna inputs (here protected with a red plastic
cap). At the top right are the IF outputs and additional output for driving
an external oscilloscope. Various sockets are available for remote control
purposes.
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Device Surveillance receiver Purpose Surveillance, monitoring, satellite downlink, bug-sweep Model MSR-904 Manufacturer Micro-Tel Country USA Year 1982 Frequency ➤ see frequency bands Noise 20-22 dB Readout 5-digit LED display, 1 MHz resolution, accuracy ±1% Tuning Electronic Modes ➤ see tuning modes Preselection ≥ 500 MHz: tracked YIG filter, < 500 MHz: low-pass filter Tuning indicator 9-segment LED bar 3rd order intercept +5dBm AFC 10:1 correction Signal indicator 10-segment LED bar LO antenna leakage ≤-70dBm (above 12 GHz: ≤-60dBm) RFI Fully RFI-shielded Image rejection >70dB, 60dB above 12 GHz IF rejection >80dB LO sample -10dBm nominal RF inputs Type N, 50Ω nominal IF gain control 60dB range (automatic or manual) IF bandwidths 0.1, 1, 5, 30 MHz (other bandwidths optionally available) IF attenuator 99dB in 1dB steps IF reference RF level measurement to ±1dB accuracy with calibration chart Demodulator outputs AM (2Vpp 50Ω), FM (2Vpp 50Ω), Audio (5mW 600Ω) Oscilloscope Hor: 3Vpp DC 1000&Omega. Blanking: +5V pulse at 5000Ω Digital control Parallel data, TTL compatible (frequency, band, mode, etc.) Power 115/230V AC ±10%, 50-400 Hz, 120W Temperature 0-50°C Size 19 x 17 x 5¼ inches Weight 40 pounds
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30 MHz - 500 MHz Requires option (3) 500 MHz - 18 GHz Standard 18-26 GHz Requires option (8) and external FE-904 26-40 GHz Requires option (8) and external FE-904
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250 MHz Remote tuner output: 40 MHz bandwidth, ≤+5dBm 160 MHz Internal 250/160 MHz convertor, may be phase locked. BW: 20 MHz 1 70 MHz Output at rear 2 21.4 MHz Leveled output, -20dBm ±3, dynamic range 50dB
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Requires option (4B).
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Requires option (4C).
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CW Duals-speed frequency control ΔF0 Variable, 0 to ±5% around current center frequency F1-F2 Scan between F1 and F2, variable marker Band Scan of push-button selected band with frequency marker Ext External tuning voltage input (0-10V)
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1 MSR-904A receiver (500 MHz - 18 GHz) 2 LO sample for synthesizers or counters 3 Low frequency Coverage 30 MHz - 500 MHz 4A 1 21.4 MHz IF output 4B 160 MHz IF output, phase lockable with synthesizer 4C 70 MHz IF output, phase lockable with synthesizer 5 Special IF bandwidths (custom) 6 IF reference, measure RF amplitude to 1dB with calibration chart 7 1 Auto-stop 8 Provision for 18-40 GHz
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Standard on MSR-904A (ordered separately on MSR-904).
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AP-904 Antenna pre-amplifier 30 MHz - 18 GHz 1 FE-904 Frequency extender 18-26 GHz and/or 26-40 GHz DC-904 Digitally refreshed CRT FCS-904 Frequency counter/synthesizer MPC-1100 Computer controller IO-1000-904 IEEE-488 bus interface unit
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Requires option (8) for MSR-904A.
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- MSR-904A - 0.03-18 GHz digitally controllable microwave surveillance receiver
Brochure. Micro-Tel (Adams-Russel). February 1989. 1
- MSR-904A - Specifications
Micro-Tel. Date unknown. 1
- Operating and maintenance manual for Micro-Tel MSR-904A
Micro-Tel (Adams-Russel). April 1983. 2 parts.
- Operating and service manual for Micro-Tel MSR-904A
Micro-Tel (Adams-Russel). September 1983. 3 parts.
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Obtained via Terry O'Laughlin, Black Radios website.
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© Crypto Museum. Created: Tuesday 17 October 2017. Last changed: Saturday, 15 March 2025 - 15:52 CET.
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