[Nymrod121]

Hello Dave,

As a first move, how about wrapping the entire frequency counter in aluminium foil as a temporary measure to see whether the interference is indeed being radiated through the plastic box? (also: try this with - then without - the Meteor's counting input being in parallel with the signal generator and the tuner-under-test).

From personal experience with frequency counter circuits used on FM tuners, comprehensive screening and robust decoupling of power supply leads (feedthrough capacitors etc.) is essential. I'm recollecting a General Instruments Application Note for the AY-5-8100 that I had a go at building some years ago. The wideband 'shash' it generated was very difficult to cure, especially the frequency readout (a Futaba 5-LT-03 fluorescent display).

I hope this helps.

Best wishes
Guy