4 mhz Resonators

Blackbird455

I occasionally get a little radio interference in the 150mhz band when running a BS1 with a 4mhz resonator.
Is there any practical way to shield this? Or is it even the resonator ?

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Noli nothis permittere te terere

Mike Green

It's not the resonator itself. It's the fact that you've got sharp square waves, some switching at 4MHz. The harmonics should attenuate pretty rapidly, but, if you've got the right length leads to act as an antenna, you could get a little signal at 150MHz. There are all kinds of ways to shield this ... Make sure you've got a 0.1uF capacitor across the power leads at the BS1. Put a grounded shield around the BS1 circuit itself. Use ferrite beads on any signals into or out of the BS1, particularly outputs. Start with the power supply filtering and the shield. Use shielded cable or twisted pairs for any long (more than a few inches) signal lines.