Frederick Electronics 1203 FSK demodulator

© Brooke Clarke, N6GCE


Frederick 1203 FSK Demod
F1203 Back

F1203 Inside

Description

The Frederick Electronics Model 1203 FSK demodulator is designed to provide optimum detection of frequency shift keying signals with shifts between 0 and 1000 cps, and with keying rates up to 74.2 baud. This 1 Rack unit (1 3/4") high demodulator was made in the golden age of electronics, i.e. it is solid state construction usingdiscrete components so is easy to maintain.  May be the most advanced RTTY demodulator made for single channel signals.  It will work with Mark only, Space only or both.

There is a front panel tuning meter and in addition there are Mark and Space lights to aid in tuning in a signal.

Made utilizing US Patent 2,999,925 "Variable Decision Threshold Computer" Sep. 12, 1961 assigned to Page communications Engineers   Class # 375/317  In manual paragraph 4.2.8 Decision Threshold Computer there is a description of how the threshold between Mark and Space is dynamically adjusted for optimum signal/noise ratio.

It has an attached 3 wire line cord and wires for the 600 Ohm balanced audio input from a receiver and a jack for a current loop connection to a RTTY (RAT) machine.

Manual

The 1966 partial reprint manual contains the following chapters:

Related Equipment

The CV-89A/URA-8A is a Military tube type FSK converter with a CRT type tuning indicator.
The CV-483/URA-17 is a solid state FSK converter with a CRT type tuning indicator.
The  MD-1142 (BR Communications 6029C) Time Deversity Modem
The Frederick 600A is a rack mount modular digital communication test set.
Digitech also made a modular rack mount Digital Data Generator test set
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