28 April 2015

Pixie kit - does not oscillate

The 40m Chinese Pixie replica does not work. The oscillator does not start. Can't get simpler than this.

Besides some capacitor values very different from most common designs, I cannot get the oscillator to start if the RIT/VXO arrangment is in place.

When the varicap diode (reverse polarized 1N400x) is shorted the oscillator runs smootly. Otherwise nothing happens. The supplied diode is OK, because I replaced it with no improvement.

The coupling capacitor to the PA stage isn't guilty either, since I removed it and still no oscillation.

There must be something wrong in the cap value at the RIT/XIT side. It is one of those capacitors where the documented value doesn't match.

Further investigation is needed. With a Manhattan/dead-bug layout would have been easier and safer.