Verify period.

   Input signal is applied to the Circuit I/P and is amplified
   and drives the two tuned circuits. This test sets the bias
   on the comparator U1 pin 5 and pin 11 so that verification occurs
   at the correct time. The O/P of the comparator is on TP7.

Fault finding:
   Bias components are RV4,R16,R19 the bias point is dc coupled by C19
   Check values, Soldered joints, and look for solder bridges

