Erik..
Two things here confuse me.
1 - I've looked at the SA612 spec sheet. I can't see anything that tells me what the maximum input is before the device is destroyed.
That would determine what methodology and parameters to design any protection circuit for.
2 - Wouldn't a diode introduce capacitance across Ch0 ? Or inductive lead effects at VHF/UHF and ruin any measurements ?
73 de Andy
