[HomeBrew] NE602 Mixer

[R. Blackman]

Hello to all in the group.

I am considering building a 2nd Local oscillator mixer using an NE602 / 
NE612  IC

The oscillator frequency  will be 72 MHz using a fundamental 72 MHz crystal.

Pins 6 and 7  of the NE602 can be configured as a collpits oscillator, using 
the crystal and the two feedback capacitors.

My question for the group:  how does one determine the value of the 
capacitors?
My guess is that they are around 100 pF, but it would be nice to know how to 
really get the values.

http://www.pan-tex.net/usr/r/receivers/ra01087.htm   DATASHEET FOR NE602

Thanks for any ideas

Richard VA3NDO