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MG-80 Burst Encoder (DDR)
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The MG-80 was a high-speed burst encoder developed by RFT in Zwonitz
(in the former 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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It's a fully electronic transistorised device, that was built to very high
quality standards.
It features a high quality keyboard that 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 the knobs just above the keyboard.
The built-in memory allowed 6 messages to be stored simultaneously
with a total capacity of 768 characters. When sending directly from the
keyboard, a 16-character buffer allowed typing at a higher speed
and prevented overruns.
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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
in four different formats.
Teletype signals are transmitted at 45, 50, 100, 200 or 300 baud from
two separate outputs.
The MG-80 was used for transmitting messages at very high speed in order
to minimise the risk of detection, but also as a training device for
future morse code operators. When used for training purposes, the space
between characters and words could be extended.
A complete MG-80 setup consists of the main unit and a separate power
supply unit (PSU). Furthermore it came with its own set 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.
It was built in December 1988 and never saw service.
The drawing above shows a typical MG-80 installation.
On the left are the optional morse key and telex unit (e.g. the F-2000).
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 added.
The heater is controlled from the MG-80 and needs approx. 15 minutes
before the MG-80 can be used reliably.
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At the heart of the MG-80 is a CPU (German: ZRE, Zentrale RechenEinheit)
based on the Robotron Z-2521 board (part of the K-1520 computer systems).
It features a UA880 processor, which was in fact a clone of the Zilog Z-80.
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 (PIO: Peripherial Input Output).
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. When the temperature inside the MG-80 is below
0°C, the K-2521 board is kept in reset.
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There are two versions of the MG-80. The basic MG-80 is suitable for
transmission of morse only. The MG-80M however has a built-in receiver
for morse and teletype signals. It can be used for the automatic
reception of such signals. The one shown here is the basic MG-80
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