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,
The MSR-904A is an enhanced version of the MSR-904.
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.
Requires option (3).
Requires option (8) and external FE-904 frequency extender.
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
Frequency➤ see frequency bands
Readout5-digit LED display, 1 MHz resolution, accuracy ±1%
Modes➤ see tuning modes
Preselection≥ 500 MHz: tracked YIG filter, < 500 MHz: low-pass filter
Tuning indicator9-segment LED bar
3rd order intercept+5dBm
Signal indicator10-segment LED bar
LO antenna leakage≤-70dBm (above 12 GHz: ≤-60dBm)
Image rejection>70dB, 60dB above 12 GHz
LO sample-10dBm nominal
RF inputsType N, 50Ω nominal
IF gain control60dB range (automatic or manual)
IF bandwidths0.1, 1, 5, 30 MHz (other bandwidths optionally available)
IF attenuator99dB in 1dB steps
IF referenceRF level measurement to ±1dB accuracy with calibration chart
Demodulator outputsAM (2Vpp 50Ω), FM (2Vpp 50Ω), Audio (5mW 600Ω)
OscilloscopeHor: 3Vpp DC 1000&Omega. Blanking: +5V pulse at 5000Ω
Digital controlParallel data, TTL compatible (frequency, band, mode, etc.)
Power115/230V AC ±10%, 50-400 Hz, 120W
Size19 x 17 x 5¼ inches
30 MHz - 500 MHzRequires option (3)
500 MHz - 18 GHzStandard
18-26 GHzRequires option (8) and external FE-904
26-40 GHzRequires option (8) and external FE-904
250 MHzRemote tuner output: 40 MHz bandwidth, ≤+5dBm
160 MHzInternal 250/160 MHz convertor, may be phase locked. BW: 20 MHz 1
70 MHzOutput at rear 2
21.4 MHzLeveled output, -20dBm ±3, dynamic range 50dB
Requires option (4B).
Requires option (4C).
CWDuals-speed frequency control
ΔF0Variable, 0 to ±5% around current center frequency
F1-F2Scan between F1 and F2, variable marker
BandScan of push-button selected band with frequency marker
ExtExternal tuning voltage input (0-10V)
1MSR-904A receiver (500 MHz - 18 GHz)
2LO sample for synthesizers or counters
3Low frequency Coverage 30 MHz - 500 MHz
4A 1 21.4 MHz IF output
4B160 MHz IF output, phase lockable with synthesizer
4C70 MHz IF output, phase lockable with synthesizer
5Special IF bandwidths (custom)
6IF reference, measure RF amplitude to 1dB with calibration chart
7 1 Auto-stop
8Provision for 18-40 GHz
Standard on MSR-904A (ordered separately on MSR-904).
AP-904Antenna pre-amplifier 30 MHz - 18 GHz 1
FE-904Frequency extender 18-26 GHz and/or 26-40 GHz
DC-904Digitally refreshed CRT
IO-1000-904IEEE-488 bus interface unit
Requires option (8) for MSR-904A.
- 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.
Obtained via Terry O'Laughlin, Black Radios website.
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© Crypto Museum. Created: Tuesday 17 October 2017. Last changed: Tuesday, 24 October 2017 - 05:28 CET.