Checking Signal Generator Accuracy With A Frequency Counter and Scope

[Notimetolooz]

You definitely want to turn the modulation off while you check the RF frequency. Sometimes you will get an unstable or incorrect reading on a frequency counter if the signal level is too low and sometimes if the signal is so big it is causing the counter input circuits to distort. I have a SG-8 and like other generators of that vintage the amplitude varies a lot as you change the frequency. The signal also has lots of distortion on much of the frequency range, the harmonics can be used as a source of higher frequency. BTW, the modulation isn't very linear. I modified the circuit by adding another tube just for modulation. After working in a modern electronics lab I'm surprised that people were able to get radios adjusted right.