CV-89A/URA-8A Frequency Shift Converter

©Brooke Clarke, N6GCE


This is a Navy military tube type rack mount FSK converter that was designed for use in the URA-8B comparator group with another CV-89 and the CM-22/A comparator to provide dual diversity reception of RTTY signals.  Audio center frequencies of 1,000 (narrow shift) and 2,550 Hz (wide shift) are supported.  The shift range can be anywhere from 10 Hz to 200 Hz for the narrow shift and 200 to 1,000 Hz for wide shift.
The manual mentions revivers RBA, RBB and RBC as elated equipment

The upper push buttons on the handles allow the drawer to slide out.  The lower handle push button allow the chassis to tilt once it is out.  This requires rack mounting to prevent tipping.  Once the drawer is out of the box the chassis can be lifted free of the slides.

The construction is modular with a number of Sub Units:


T.O. 21R1-2URA8-11 Frequency Shift Converter-Comparator Group AN/URA-8B and Frequency Shift COnverter CV-89A/URA-8A
1 Dec 1952, Change 1 1 April 1975. (mine is a partial repro)

Tube Complement

OA2, 1Z3, 2BP1, 2 ea 6AL5W, 2 ea 6AQ5, 6X4, 4 ea 12AX7, 4 ea 12AU7, 991, total of 17 tubes.

AC Power Cord

The connector on the 120 VAC power cord is a Cannon AN-3106B-14S-79, A = Neutral, B= Gnd, C = Hot


Powers up, power lamp lights and CRT shows a trace.  Not tested beyond this.  Guaranteed not DOA, but not to any specs.

Shipping Weight

about 50 pounds

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 Frederick 1203 FSK Demodulator
The Frederick 600A BER test set
Digitech also made a modular rack mount Digital Data Generator

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