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General Radio 1209-BL
Unit Oscillator
General Radio 1209-BL Unit Oscillator

Available from 1959 to 1961

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

The General Radio 1209-BL Unit Oscillator was introduced in Catalog P (1959) and remained available through Catalog Q (1961).

The Type 1209-BL is a general-purpose frequency source covering 180 to 600 MHz. It uses a "butterfly circuit" to determine frequency. There are no sliding contacts, which makes swept operation possible. Direct amplitude modulation at audio frequencies is accessible by a phone jack on the oscillator housing.

Available as an accessory were crystal-diode modulators 1000-P6 or 1000-P7 that can provide amplitude modulation at frequencies from 0 to 5 MHz. Pulse or square-wave modulation is available with the Type 1264-A modulating power supply.

As part of the unit oscillator series, the 120i-BL requires an external power supply, 1203-B and 1201-A are recommended. The 1209-BL is similar to 1209-B in design, construction and specifications except frequency range.


  • Frequency Range: 180 to 600 MHz
  • Frequency Calibration Accuracy: 1%
  • Warmup Frequency Drift (Typical): 0.2%
  • Output Power: 300 mW into 50 Ω with Type 1203-B power supply