It's a little convoluted, but here goes.
The signal on each side of the coil is 180° out of phase, unless it is grounded. In this case the ground is put between the capacitors, which means each side of the LC has 180° signals on it.
The transistor amplifier inverts the signal 180°, which when feed into this LC signal is inverted again. Remember what I said about positive feedback and amplifiers? This is such a case.
BTW, this really was one of my Dad's least favorite circuits. The transistor amp will overamplify the signal, which means that it won't be much of a sine wave without some tweaking on the design. It is a classic RF oscillator, but easy to build.
The signal on each side of the coil is 180° out of phase, unless it is grounded. In this case the ground is put between the capacitors, which means each side of the LC has 180° signals on it.
The transistor amplifier inverts the signal 180°, which when feed into this LC signal is inverted again. Remember what I said about positive feedback and amplifiers? This is such a case.
BTW, this really was one of my Dad's least favorite circuits. The transistor amp will overamplify the signal, which means that it won't be much of a sine wave without some tweaking on the design. It is a classic RF oscillator, but easy to build.