04-01-2013, 04:34 PM
To get a stable trace try this:
Remove modulation from cct
Connect scope probe earth to -ve of cct
Connect RF choke (value not critical) between scope probe centre and earth
Place sort bit of wire from from probe centre/choke junction and put near oscillator o/p
Turn up mod
It looks like the scope is picking up mains hum (since there is not much signal from the cct) and this arrangement mostly eliminates that.
Ian
Remove modulation from cct
Connect scope probe earth to -ve of cct
Connect RF choke (value not critical) between scope probe centre and earth
Place sort bit of wire from from probe centre/choke junction and put near oscillator o/p
Turn up mod
It looks like the scope is picking up mains hum (since there is not much signal from the cct) and this arrangement mostly eliminates that.
Ian
