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General Radio 1218-A
Unit Oscillator
General Radio 1218-A Unit Oscillator

Available from 1959 to 1963

Catalog History
 Document Year Page
Catalog O 1956 117
Catalog P 1959 115
Catalog Q 1961 112
Catalog R 1963 115
(All manuals in PDF format unless noted otherwise)

The General Radio 1218-A Unit Oscillator was introduced in Catalog P (1959) and remained available through Catalog R (1963).

The 1218-A is a general-purpose frequency source covering 900 to 2000 MHz. It finds use as a generator for bridges, admittance meters, and impedance meters. Being part of the Unit Oscillator family, it requires a separate power supply or a modulating power supply. The Type 1263-B is one of the recommended power supplies.

Direct amplitude modulation at audio frequencies is provided by a front panel phone jack. With a 1000-P6 Crystal Diode Modulator accessory, modulation from 0 to 20 MHz is possible that is essentially free of FM.

The output of the Type 1218-A can be monitored by a voltmeter and can be kept constant by the Type 1263-B Amplitude-Regulating Power Supply. In combination with an 874-GA Attenuator, an 874-VR Voltmeter Rectifier, and an 874-VI Voltmeter Indicator, the 1218-A provides an accurately known output voltage for receiver testing.

The recommended sweep drives are types 908-P1, 908-P2, 908-R12, 908-R96, and 1750-A.

A Sylvania 5675 UHF medium-μ pencil triode is used as the oscillator tube, see below for the data sheet.


  • Frequency Range: 900 to 2000 MHz.
  • Frequency Calibration Accuracy: ±1
  • Warm-up Frequency Drift: 0.1%
  • Output Power: 200 mW into a 50 Ω load