Why doesn't my circuit oscillate?

[saviobez]

First, sorry for my bad english.

I'm building a project using a Colpitts Oscillator with Differential Pair, designed for ~117.6MHz. I'm using LTspice for simulation. The oscillator individually oscillates, but I need it to oscillate when I add a sensor model (as seen in the image in the circuit's feedback loop). When I add the sensor it initially wobbles and then stops, any ideas how I can fix this?

 

[kellys_eye]

If it 'stops' oscillating then you have too much attenuation in the feedback path/insufficient loop gain.

 

[CircutScoper]

First, sorry for my bad english.

I'm building a project using a Colpitts Oscillator with Differential Pair, designed for ~117.6MHz. I'm using LTspice for simulation. The oscillator individually oscillates, but I need it to oscillate when I add a sensor model (as seen in the image in the circuit's feedback loop). When I add the sensor it initially wobbles and then stops, any ideas how I can fix this?

Try decreasing R3 to 1k.