[HBR] options for the 2nd oscillator

[Ian Wilson]

Hi John,

I have had no problem using modern crystals with tube oscillators at
typical receiver voltage levels (in fact, I have only had 1 failure with a
modern crystal in a 6AG7 transmitter oscillator, and that may not have
had anything to do with the voltage levels).

You can operate the tube oscillator on reduced plate/screen voltage if
you are really concerned with this.

You can also use a small pentode such as a 6AU6 in a Colpitts-type
(sorry, I mean grid-plate <g>) configuration. This gives you more control
over the amount of feedback and thus the drive that the crystal sees. The
pentode has a lot more effective voltage gain than the triode, so the
(AC) voltages on the grid side can be smaller.

73, ian K3IMW