GR Unit Instruments are a series of separate oscillator units, power supplies and detectors that can be combined in a variety of ways to provide exactly the desired characteristics for a given RF measurement.  For each of the instruments described below I have listed the prices shown in the GR catalogs in my collection.  Catalog O (Jun-1956) and Catalog T (Feb-1968) are online at the BoatAnchor Manual Archive.

This basic supply provides maximum RF output for a unit oscillator.  Prices in GR catalogs: M (Oct-1951) $47.50, N (Jan-1954) $40.00, O (Jun-1956) $40.00.

Frequency coverage of these units is 50 to 250 MHz, with a frequency accuracy of ±1%.  Output into 50 Ω is 80 mW for the -B and 100 mW for the -C.  1215-B prices in GR catalogs: O (Jun-1956) $190.00, P (Apr-1959) $190.00, Q (May-1961) $210.00 1215-C prices in GR catalogs: R (May-1963) $210.00, S (Jul-1965) $225.00, T (Feb-1968) $295.00, U (Feb-1970) $325.00, 73 (Nov-1972) $370.00.  The Type 1215-B manual is online at the BoatAnchor Manual Archive.

The purpose of this unit is to serve as part of an RF null detector that rejects noise and interfering signals.  It contains four IF amplifier stages tuned to 30 MHz.  With the appropriate unit oscillator and mixer-rectifier it forms a sensitive heterodyne detector for VHF and UHF bridge measurements.  Prices in GR catalogs: N (Jan-1954) Price on request, O (Jun-1956) $335.00, P (Apr-1959) $335.00, Q (May-1961) $340.00, R (May-1963) $360.00, S (Jul-1965) $375.00, T (Feb-1968) $475.00.  The Type 1216-A manual is online at the BoatAnchor Manual Archive.

This supply equips a unit oscillator to provide constant power output as the oscillator frequency is varied.  Prices in GR catalogs: S Supplement (Feb-1967) $485.00, T (Feb-1968) $550.00, U (Feb-1970) $600.00, 73 (Nov-1972) $675.00.

This supply provides 100% pulse and square wave modulation for VHF and UHF unit oscillators.  Prices in GR catalogs: Q (May-1961) $285.00, R (May-1963) $285.00, S (Jul-1965) $285.00.

This unit covers 450 MHz to 1.05 GHz with a calibration accuracy of 1%.  Maximum output is 150 mW into 50 Ω, and is adjustable over more than 80 dB with the internal trombone coaxial attenuator.  Prices in GR catalogs: Q (May-1961) $285.00, R (May-1963) $285.00, S (Jul-1965) $300.00, T (Feb-1968) $395.00, U (Feb-1970) $445.00, 73 (Nov-1972) $495.00.