Description Corrected 09/22/2021 - A copy of the Plantronics/Fredericks Manual on CD comes with this set.
For Sale: A Frederick / Plantronic Model 1273/S1 FSK Teletype Keyer - Demodulator is set for a single shift. Typically they have a frequency shift of 850kHZ and looks at baud rates of 75 or 600. Shift frequency is determined by two crystals labeled Mark & Space on the Tone Keyer board inside the unit. The installed crystals are Mark 2182.5 kHZ and Space 1417.5 kHZ. The I/O lines are attached from the rear and there is a switch to toggle I/O to coax (75 ohm) or open lead (600 ohm). Construction is mil spec: G10 boards with protective coating. Power supply appears good as unit powers up and all fuses are good.
The 1273 is a single shift unit so far as I can tell, designed for dedicated "slave" service. Examples of possible application include ITTY, ham radio narrow shift, or dedicated and secure between office data connection for a business.
Unit measures 2" high and 19" by 19" in size. For ham use,
recrystallize using 2125 kHZ for the MARK frequency (for
both 170 & 850 shifts) and use 2295 kHZ and 2975 kHZ for SPACE
respectively.
Should be a lot of fun for the right person.
Condition: Excellent physical condtion. Unit powers up fine. Keyer output level still set and responds when selected. We have no way to further test this unit. An experienced teletype person should be successful recrystallizing the unit to amateur radio preferences. Re-purposing this involves changing the upper & lower shift point crystals and adjusting, to what extent possible, the baud rate.
Terms: Sold as described but strictly as is. We do not accept returns as we are downsizing and not retailing.