liberal
Advanced Member level 4
amplifier oscillate
in my downconverter,the IF part after mixer is
a BPF1 (60MHz LC)---->MMIC RF amplifier(Gali-5 mini)---->BPF2(60MHz LC)--->detectorwithout signal in,i measure the signal after BPF2 there is a frequency at about 150MHz,about -31dbm,then i disconnect BPF1 and amplifier ,then measure the signal after BPF1,there is no signal.then i disconnect amplifier with BPF1 and BPF2,then measure the amplifier output ,there is a 150MHz signal ,which has the same amplitude as measurement first.then i connect BPF1 and amplifier ,then touch the path between BPF1 and amplifier with my hand,then the signal measured above disappear.anyone can explain this?amplifier oscillates?how to solve it?
in my downconverter,the IF part after mixer is
a BPF1 (60MHz LC)---->MMIC RF amplifier(Gali-5 mini)---->BPF2(60MHz LC)--->detectorwithout signal in,i measure the signal after BPF2 there is a frequency at about 150MHz,about -31dbm,then i disconnect BPF1 and amplifier ,then measure the signal after BPF1,there is no signal.then i disconnect amplifier with BPF1 and BPF2,then measure the amplifier output ,there is a 150MHz signal ,which has the same amplitude as measurement first.then i connect BPF1 and amplifier ,then touch the path between BPF1 and amplifier with my hand,then the signal measured above disappear.anyone can explain this?amplifier oscillates?how to solve it?