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.

The Type 1231-B is a sensitive visual null indicator for audio-frequency bridges.  It can also be used as a high-gain (>80 dB) audio amplifier.  Frequency response is essentially flat from 50 Hz to 5 kHz and usable for null indications at reduced sensitivity from 10 Hz to 100 kHz.  An external fixed or adjustable filter (see Type 1231-P2 below) can be used to sharpen the null indication.  I use my Type 1231-B as a detector for my Type 1603-A Z-Y Bridge and with other GR bridges.  Prices (with AC Power Supply) in GR catalogs: L (1948) $290.00, M (Oct-1951) $370.00, N (Jan-1954) $378.00, O (Jun-1956) $378.00, P (Apr-1959) $388.00.

The Type 1231-P2 is a fixed-frequency filter used with the Type 1231-B Amplifier and Null Detector.  It suppresses harmonics, noise and hum for measurements at 400 Hz and 1 kHz.  Prices in GR catalogs: L (1948) $20.00, M (Oct-1951) $25.00, N (Jan-1954) $25.00, O (Jun-1956) $30.00, P (Apr-1959) $38.00.

For decades this was the standard instrument used to measure FM and TV antennas and transmission lines.  Although it is listed with the bridges it is, technically speaking, not a bridge.  The Type 1602-B uses three coaxial lines at right angles, one terminated by the unknown admittance and the other two terminated by a pure resistance and a pure rectance.  Sampling loops in the three lines are connected in parallel, and when the loops are adjusted to produce a null the parameters of the unknown are displayed.  It is direct reading from 40 MHz to 1.5 GHz, and can be extended to 20 MHz with a correction.  The two multipliers (faceplates) provide admittance measurements from 0.01 mmho to 10,000 mmho and susceptance measurements from -200 to +200 mmho.  Basic accuracy is 3%.  Prices in GR catalogs: N (Jan-1954) $295.00, O (Jun-1956) $295.00, P (Jun-1959) $295.00, Q (May-1963) $295.00, R (May-1963) $325.00, S (Jul-1965) $365.00, T (Feb-1968) $465.00, U (Feb-1970) $550.00, 73 (Nov-1972) $580.00.  The Type 1602-B manual is online at the BoatAnchor Manual Archive.

The Type 1603-A is a versatile instrument that can measure any impedance from zero to infinity at any audio frequency.  Impedance (Z) components (resistance and reactance) can be measured from 0 to 1,050 Ω.  Admittance (Y) components (conductance and susceptance) can be measured from 0 to 1,050 μmhos.  The frequency range is 20 Hz to 20 kHz, and the bridge requires an external oscillator and null detector.  R and G are direct reading with an accuracy of 1%.  X and B are direct reading at 100 Hz, 1 kHz and 10 kHz (scalable at other frequencies) with an accuracy of 1% to 7 kHz, 2% to 15 kHz and 3% to 20 kHz.  I use my Type 1603-A to measure the impedance of speakers, A-F transformers, and audio inputs in amplifiers and transmitters.  Prices in GR catalogs: O (Jun-1956) $355.00, P (Apr-1959) $370.00, Q (May-1961) $450.00, R (May-1963) $475.00, S (Jul-1965) $515.00, T (Feb-1968) $750.00.  The Type 1603-A manual is online at the BoatAnchor Manual Archive.  See also the Technology Instruments Type 310-A Z-Angle Neter.

For decades this was the standard instrument used to measure AM broadcast band and shortwave antennas and transmission lines.  It is an improved version of the Type 916-A, the first successful radio-frequency bridge.  It covers 400 kHz to 60 MHz.  The resistance range is from 0 to 1,000 Ω and is direct reading.  Reactance is direct reading at 1 MHz with a range of ±5,000 Ω.  Reactance readings must be scaled for other frequencies - the range at 400 kHz is ±12,500 Ω and at 60 MHz is ±83.3 Ω.  Basic accuracy is 1% for resistance and 2% for reactance.  This one has a lot of miles on it - the previous owner was a radio engineer who used it for decades to measure AM antenna systems.  Prices in GR catalogs: O (Jun-1956) $590.00, P (Apr-1959) $620.00, Q (May-1961) $660.00, R (May-1963) $750.00, S (Jul-1965) $825.00.  The Type 1606-A manual is online at the BoatAnchor Manual Archive.

This is one of a set of instruments that I occasionally use for work - see Vintage Instruments In Action.

This adaptation of the Type 1602-B circuit can characterize the network parameters of two- and four-terminal networks such as transistors, tubes, amplifiers and filters when the transfer-function indicator is used.  It can also measure the impedance or admittance of components when the immittance indicator is used.  Multiplier plates are supplied for both indicators.  It is direct reading and covers 25 MHz to 1.5 GHz.  The measurement ranges are 0 to 30 for voltage and current ratios, 0 to 1,500 Ω for transimpedance, 0 to 600 mmho for transadmittance, 0 to 1,000 Ω for impedance and 0 to 400 mmho for admittance.  Basic accuracy is 2.5% for ratios, transimpedance and transadmittance, and 2.0% for impedance and admittance.  Prices in GR catalogs: P (Apr-1959) $1,665.00, Q (May-1961) $1,775.00, R (May-1963) $1,775.00, S (Jul-1965) $1,925.00, T (Feb-1968) $2,150.00, U (Feb-1970) $2,350.00.