collins: R390A (URR), variants:

R-725 is a direction-finding set with an IF strip similar to the R-390, developed by Motorola and built by Servo and Arvin. No more than 300 sets produced.

R-1274/GRC-129 model is a special variant, widely in use by the NASA for the APOLLO effort.

For further information see Fred Osterman: Shortwave-Receivers - past and present.

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