1209-BL

The General Radio 1209-BL Unit Oscillator was introduced in {Catalog P} and remained available through {Catalog Q}.

The Type 1209-BL is a general purpose frequency source covering 180 to 600 MHz. It uses what's called a butterfly circuit to determining frequency, there are no sliding contacts making swept operation possible. Direct amplitude modulation at audio frequencies is accessible by a phone jack on the oscillator housing. Available as an accessory are crystal-diode modulators 1000-P6 or 1000-P7, frequencies from 0 to 5 MHz can be used to provide amplitude modulation. Pulse or square-wave modulation is available with the Type 1264-A modulating power supply. As part of the unit oscillator series it 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.

Specifications

• Frequency Range: 180 to 600 MHz
• Frequency Calibration Accuracy: 1%
• Warmup Frequency Drift (Typical): .2%
• Output Power: 300 mW into 50 Ω with Type 1203-B power supply

Links

• Experimenter January 1958 describing Type 1209-BL
• Litton Industries 6481 Tube Data
• Patent for the Butterfly Tuning Circuit

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