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?