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RX-1000
VHF surveillance receiver

RX-1000 is a digital VHF surveillance receiver, introduced around 1990 by Audio Intelligence Devices (AID) in Fort Lauderdale (Florida, USA), as the successor to the analogue RX-905. It has six freely programmable channels in the 150-174 MHz frequency band and was used for the reception of covert listening devices (bugs) and for monitoring of specific VHF radio channels.

The device is housed in a grey/black metal enclosure that measures 260 × 165 × 63 mm, and is shaped in such as way that it can be placed on a table, with all controls at the front panel easily accessible. All connections, with the exception of the earphones, are at the rear.

As it has the same form factor as its predecessor – the RX-905 – the RX-1000 was intended as a drop-in replacement, albeit with added functio­nality like freely programmable frequencies and up to 60 channels, all under control of in internal 8031 microcontroller — a variant of the 8051.
  

As the device has a rather poor large-signal behaviour — a strong signal in the vicinity of the receiver easily overdrives the input stage — it is less suitable as a general purpose surveillance receiver, unless it is used with an (adjustable) attenuator. It is currently unknown when the RX-1000 was first introduced, but based on the design of the PCB and the choice of components, it is likely that this was around 1990. The device shown here was manufactured around 2000. 1 A spin-off from this receiver is the Unitel 225 intelligence kit — basically a portable listening post.

  1. Based on date codes on the electronic components.

RX-1000 with descrambler
RX-1000 with descrambler
Controls
Rear panel
Operating instructions at the bottom
A
×
A
1 / 5
RX-1000 with descrambler
A
2 / 5
RX-1000 with descrambler
A
3 / 5
Controls
A
4 / 5
Rear panel
A
5 / 5
Operating instructions at the bottom

Features
The image below provides a quick overview of the controls and connections of the RX-1000. All controls are located at the front panel, which consists of a horizontal and a vertical plane. The horizontal plane holds the volume and squelch controls, plus an LCD with push-buttons. The vertical place holds an output socket (3.5 mm jack), an output selector to control the level, and an (optional) selector for the descrambler. Provisions are present for additional features.


All connections are at the rear of the device, which the exception of the output socket, which is at the front. The device can be powered from the 115V or 230C AC mains, configurable with a slide switch at the rear. A fairly large speaker is located under the black grille at the top. At present, no instruction manual is available, but fortunately, short-form instruction are printed at the bottom.




Interior
The interior of the device can be accessed by removing four screws from the upper case shell — two at the left and two at the right — after which the case shell can be removed. To get full access to the PCB, it will be necessary to remove the black front panel cover as well. The is done by removing two screws at the front, plus the two knobs of the volume and squelch controls.

Interior - left angle view
Interior - right angle view
Interior - top view
Interior (front panel removed)
Display and 80F31 processor
Synthesizer
Front end and 1st mixer
Front end and 1st mixer
2nd IF and AF circuits
Main oscillator hidden under the synthesizer
Power and AF amplifier circuits
AF amplifier
Mains power supply unit
Descrambler board
Descrambler board
Dummy board (used when descrambler is not fitted)
B
×
B
1 / 16
Interior - left angle view
B
2 / 16
Interior - right angle view
B
3 / 16
Interior - top view
B
4 / 16
Interior (front panel removed)
B
5 / 16
Display and 80F31 processor
B
6 / 16
Synthesizer
B
7 / 16
Front end and 1st mixer
B
8 / 16
Front end and 1st mixer
B
9 / 16
2nd IF and AF circuits
B
10 / 16
Main oscillator hidden under the synthesizer
B
11 / 16
Power and AF amplifier circuits
B
12 / 16
AF amplifier
B
13 / 16
Mains power supply unit
B
14 / 16
Descrambler board
B
15 / 16
Descrambler board
B
16 / 16
Dummy board (used when descrambler is not fitted)

Restoration
The devices in our collection had probably been unused for a number of years, before they were obtained from a government sale. This means that it was likely that they had not been powered up for at least 10 years. First of all, we had to set the voltage selector at the rear to 230V AC.

Next, we thoroughly inspected the interior to check for any damaged parts. Apart from a loose descrambler board in one of the units, that was easily refitted, every­thing seemed to be in good shape. But when the device was powered up, it immediately blew the mains fuse in the house.

As the AC transformer checked out OK, this pro­blem was likely caused by the mains filter, which consists of two 10nF/1000V capacitors that are soldered directly to the mains socket at the rear of the device. The two capacitors were tem­po­rarily removed to see if they caused the problem.
  

As this resolved the problem, this means that one of the two capacitor (or both) had not survived. After replacing the capacitors with new 1nF variants, the receiver powered up correctly. The volume and squelch controls appeared to work as expected. Next, a suitable frequency was programmed into one of the channel memories, and a known good covert body transmitter was used as a test device. The signal came through loud and clear, which means that the device is OK.


Specifications
  • Device
    Digital surveillance receiver
  • Purpose
    Bug reception, frequency monitoring
  • Manufacturer
    Audio Intelligence Devices (AID)
  • Model
    RX-1000
  • Country
    USA
  • Year(s)
    1990-2000
  • Predecessor
    RX-905
  • Band
    VHF-H
  • Channels
    60
  • Frequency
    150-174 MHz
  • Spacing
    2.5 kHz
  • Method
    Digital, freely programmable
  • Modulation
    FM narrow band
  • Antenna
    50Ω BNC
  • Mains
    110V or 230V AC (switch selectable)
  • Dimensions
    260 × 165 × 63 mm
  • Weight
    1618 g
Surviving serial numbers
  • 1357
    Crypto Museum
  • 5001
    Crypto Museum 1
  1. This version does not contain an EPROM. Instead the software is stored in a one-time programmable microprocessor.

Further information
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Crypto Museum. Created: Tuesday 16 January 2024. Last changed: Sunday, 21 January 2024 - 16:57 CET.
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