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MEL L662
Miniature communications receiver - wanted item

L662 is a miniaturised LW/MW/SW communications receiver for the 40 kHz to 30 MHz range, introduced in 1967 by MEL Equipment Co 1 in Crawley (Sussex, UK). The receiver was developed for use by the Navy, the Army and for intelligence purposes, but was also commercially sold.

The device is housed in a die-cast aluminium enclosure that measures 153 × 83 × 38 mm — slightly larger than a hand — and weights less than one kilogram, mercury batteries included.

The transistorised design consist of the first generation of integrated circuits (ICs), along with miniaturised circuits built on film sub­strates. At the center of the unit is a digital read­out that shows the currently selected frequency. The MHz digit selects the appropriate harmonic from an internal 1 MHz crystal oscillator, whilst the 100 kHz digit selects one of 10 additional crystals.
  
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Fine tuning is done with the built-in Beat Frequency Oscillator (BFO), which can also be used to calibrate the receiver. The device is powered by two TR-134 mercury batteries — made by Mallory — that are held in a removable unit at the rear end. At the left side are two banana sockets for connection of a antenna and ground wires. A bracket with a built-in BALUN can be installed in these sockets, allowing the use of the supplied telescopic antenna or an external one (via coax).

The L662 is suitable for the reception of AM, CW and, by using the BFO, Single Side Band (SSB) signals. Demodulated audio is delivered to a high-impedance hearing aid style earpiece that is connected at the front. The device was first introduced to the public in Wireless World of June 1967 as a pocket receiver [2] . Although its price is unknown, it was probably too expensive for the average hobbyist, given the fact that LEMO connectors are used for earpiece, antenna and AGC. It is therefore more likely that the device was actually intended for professional use.

  1. At the time (1967) MEL was a subsidary of Philips.

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Specifications
  • Device
    Miniature communications receiver
  • Model
    L662
  • Manufacturer
    MEL
  • Country
    UK
  • Customers
    CIA, MI5, MI6
  • Power
    2 × Mallory TR-134 mercury battery
  • Duration
    25 hours of contunuous operation
  • Antenna
    Telescopic (supplied) or external (via LEMO socket)
  • Dimensions
    153 × 83 × 38 mm
  • Weight
    907 g (batteries included)
Bands
  • LW
    40 - 300 kHz
  • MW
    300 kHz - 3 MHz
  • SW
    3 - 30 MHz
Parts
  • Storage box with polystyrene interior
  • Receiver L1662
  • 4 × Mallory TR-134 mercury battery
  • Earpiece with LEMO connector
  • Antenna bracket
  • Telescopic antenna
References
  1. Crypto Museum, Photographs of MEL L662 receiver
    Crypto Museum Archive #CM303837_A/B.

  2. New Products, Pocket Receiver
    Wireless World, June 1967. Page 306.

  3. Mallory, Duracell battery advert
    Wireless World, October 1967. Page 84. 1

  4. Free Classified Ads, MEL Mullard receiver type L662
    World Radio History, September 1985. Page 55.
  1. Obtained from www.worldradiohistory.com.

Further information
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Crypto Museum. Created: Sunday 30 October 2022. Last changed: Monday, 31 October 2022 - 09:32 CET.
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