Heathkit SG-8 Signal Generator

[Electronic M]

Zero beating: ever run 2 am radios at once and tune 1 through the band and find a point where they both squeal despite not having touched the one you weren't tuning? That's the local osc zero beating with the osc or station of the other set... In Toulouses example you would tune the Chrystal osc to the frequency of the station and listen for the zero beat then tune for minimum signal on the S-meter (exact frequency zero beat).