It's when you use CW mode, do you hear it?
The Green Caps, are those Polystyrenes/Mylar (think foil Birthday balloon material) - it's micron thickness - sandwiched between plates of Reynolds Wrap - you get the idea...
If they've gone flat, which can happen, they should be replaced.
I found this article at WIKI - under Relaxation Oscillators...
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You can read a Wiki of Relaxation Oscillators Here
The concept is to use an R/C - cascaded into two stages - using the recovery moment the caps charge then release thru the resistors - as a inception moment - this moment can be sensed by placing a device used as a switch - in this case - A Transistor using a Grounded Emitter as common - in the above example, they use a Neon bulb - but in either case, the rate of charge is modified thru R - when the cap is charged - the current intake into this circuit thru R - drops, the voltage rises - and the neon tube "fires". The tube arcs - being the gas has less resistance as an arc - the cap discharges thru the bulb, and once the cap is depleted, the value of R is too high to "sustain" the arc. The Arc stops, gas resumes it normal high-impedance (insulator value) state and the cap accepts charge thru R again.
The Collector offers a charge, and so does the Base - to the parts in the circuit. Once a cap "charges" the voltage rise it has, is modified thru a resistor tied to one lead, the other is grounded. What triggers this is - the Base to Collector difference - changing by the caps charge rates - and so the transistor switches from off on to off - then back on again - and the cycle repeats - it uses the two 0.0047 (472) caps to generate that characteristic tone - while C143 controls the level of regeneration and the "length" of the oscillation moment - modifying the tone (a log function) while the other two are simply the "burst" - C143 helps sustain the burst as providing a regenerative loop.
That 270K value? That too is a feedback loop, but controls the circuit as a level of Gain the circuit would have. Else the Transistor can self destruct from the "duty-cycle" the R/C values place on the ability to generate that tone.
Is that what you wanted to know?
