90711 Variable Frequency Oscillator

This VFO uses a temperature compensated 6SK7 vacuum tube in an electron coupled oscillator configuration. Another 6SK7 is used for a buffer or doubler and finally a 6AG7 tuned amplifier is track-tuned to the oscillator. The power supply is regulated to improve overall stability of this VFO. In addition, since there is such good isolation between the oscillator and output the oscillator will not shift in frequency with an output loading variation from open to short circuit! This VFO was designed for operation on 160, 80, 40 and 20 meters.

If you desire further information on the 90711 check out the article "The Millen Duo" which appears in Electric Radio Magazine, May 1995.

The beautiful 90711 pictured here belongs to John Brewer WB5OAU.