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Electronic morse burst encoder
The MG-80 was a high-speed burst encoder
developed by RFT in Zwönitz
(East-Germany, DDR) and was used by the East-German Army (NVA).
It is suitable for the transmission of morse
and teletype signals, and
entered service in July 1986, close towards the end of the
Cold War (1989).
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The device is microprocessor controlled and is built to high quality standards.
The high quality keyboard supports both the Latin and the Cyrillic (Russian)
alphabet. All settings (e.g. transmission speed) are
controlled via the keyboard. The output level and tone pitch can be adjusted
with knobs on the vertical panel behind the keyboard.
The built-in memory allows 6 messages to be stored simultaneously
with a total capacity of 768 characters. When sending directly from the
keyboard, a 16-character buffer prevents overruns and
allows typing at a higher speed.
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Morse signals
can be transmitted at 30, 40, 50, 60, etc. up to 999
characters per minute, which is equivalent to 10...99 groups per minute.
The morse signals are available on 4 different outputs: as an electronic
contact, a mechanical contact, as an audio tone and as a double-current signal.
In addition, a pair of heaphones can be connected for monitoring the morse
in/out signals.
Telegraphy signals in ITA2 format
are transmitted at 45, 50, 100, 200 or 300 baud. They are available from two
separate outputs, each with a constant current of 45mA.
The MG-80M also has a telegraphy input, which accepts 20mA signals.
The MG-80 was used for transmitting messages at very high speed in order to
obtain a Low Probability of Intercept (LPI) and a Low Probability of Detection
(LPD) through Radio Direction Finding (RDF).
It was also used as a training device for
future morse code
operators. When used for training purposes, the space
between characters and words could be extended.
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There are two versions of the MG-80:
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A complete MG-80 setup consists of a power supply unit (PSU)
and a separate main unit, with its own pair of headphones.
It was not classified as a secret device and was therefore not destroyed
at the end of the Cold War. As a result, many units ended up at the European
surplus market. Most of these were in used condition, but the one shown here
was found it it's original packaging on a German flea market in 2009.
It was built in December 1988 and never saw service.
The drawing above shows a typical MG-80 setup.
On the left are the optional morse key and telex unit.
The latter can be an F-2000 teletypewriter that can be used for input as
well as for output, or an F-1200 printer, which can be used for printing the
received teletype data (MG-80M only).
On the right are the transmitter (TX) and the receiver (RX). Please note
that a receiver can only be used on an MG-80M version. The MG-80 can be used
at temperatures of 0°C and higher. When turned on, it can be operated
after the self-test has completed (approx. 3 seconds). When used at
temperatures below 0°C, an optional SV80 or SV81 heater has to be used,
which is controlled from the MG-80. It takes 15 minutes
before the MG-80 can be used reliably.
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At the heart of the MG-80 is a Central Processing Unit,
or CPU (German: Zentrale RechenEinheit, or ZRE),
based on the Robotron Z-2521 board (part of the K-1520 computer systems).
It features a UA880 processor — an unlicenced microprocessor
based on the design of the Zilog Z80 [1].
The block diagram above roughly shows what is inside the MG-80.
At the heart is the Z-80 based K-2521 CPU board. The keyboard is on
the left and is connected to PIO-B.
The LEDs and the data interface are both connected to PIO-A.
Some filtering is added to the I/O lines to prevent radio interference.
At the bottom right is the temperature control unit that drives the
(optional) SV-80 heater. As the CPU can't reliably be operated at
low temperatures, the K-2521 board inside the MG-80
is kept in reset at temperatures below 0°C.
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Device Morse and telegraphy transmitter Purpose Burst transmissions, morse training Model MG-80, MG-80M (see below) Year 1986 Manufacturer RFT VEB Zwönitz Country DDR (East-Germany) Morse 30, 40, 50, 60, ... 999 characters per second (10-99 groups per minute) Telegraphy ITA2 standard at 45, 50, 100, 200, 300 baud Initialisation < 3 sec (including self-test) Outputs see below Temperature 0°C to +50°C Storage -40°C to +60°C Humidity 95% at +30°C Dimensions 395 × 380 × 175 mm Weight 9 kg
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MG-80 Basic version, for transmission only MG-80M Same as MG-80 but with reception capability
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Electronic 60V/100mA DC Mechanical Relay 110V/100mA Tone -12dB to +10dB into 600Ω Double-current ±30V into 1.5kΩ Headphones For monitoring transmitted and received signals
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© Crypto Museum. Created: Sunday 01 November 2009. Last changed: Thursday, 11 July 2024 - 18:43 CET.
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