Hi.
Maybe this is obvious for others but I'm a bit stumped.
I have a circuit consisting of a charge pump / voltage doubler which is connected to three LC tank circuits (two have trimmer caps) in series,
It is then modulated via a dual transistor pair and subsequently capacitively coupled to a high voltage DC bias circuit which drives an avalanche photodiode transimpedance amplifier circut.
Whilst probing the circuit I found that touching the coupling capacitor and/or ground, that the circuit would generate the correct signal and the device would fully function, (don't have schematics / part specs etc.)
I figured it must be a grounding issue and tried adding all manner of capacitors but none of them helped, seemingly the opposite, adjusting the trimmers also doesn't help.
Any thoughts appreciated
