What do we know about the circuit.
We the collector we'll call Rc
We have a base resistor we'll call Rb
Now there are two ways we can look at the circuit. One way is to say that the oscillator only drives the output transistor in it's linear state or class A operation. The other way is to say that the output transistor is being driven to it's extremes, on and off or class C operation.
For simplicity let's consider class A operation first.
So now we have a 3 volt supply and about 0.7 volts at the base or about 2.3 volts across Rb.
Therefore we know that the current going through Rb is 2.3 volts divided by 150Kohms giving about 15.3uA of current.
One helpful piece of information that has been discovered experimentally is that the impedance of a silicon junction is 25millivolts divided by the forward current. Therefore we calculate the impedance to be 0.025/.0000153amps or about 1.63Kohms.
The output impedance of an NPN transistor is usually very high so we will only consider the collector resistor Rc or 330 ohms. Normally we would consider the collector capacitance. From the data sheet we can conclude that the capacitance between the collector and the base is about 10pF. This capacitance is amplified by the transistor and goes up by a value of beta or in this case to about 1nF. At 90MHz this computes to about 1768ohms capacitive. This is in parallel with the 330 ohms.
This causes the output impedance to be closer to about 325 ohm slightly capacitive.
This also causes a slight decrease in input impedance also to about maybe 1.5Kohms slightly capacitive.
Now for the second case. Suppose we have a class C amplifier.
For impedance purposes we can look at the output voltage without the antenna and then with an antenna that has 0 ohms of impedance and do a thevinin equivalent to find out the output impedance. The antenna must be looked at at a 50 ohm resistor in series with a very large capacitor of 0 ohms.
So once you put the antenna on the output you will notice a big decrease in output voltage.
The input impedance depends on how much the oscillator drives this point. With a low drive the impedance will be about 1.5Kohm to close to 75Kohms. This is because the input of a PN junction looks close to a short when it is forward biased and like an open when it is reversed biased.
Now how much signal is coming from the oscillator?
I will dig into this more later after I sleep but in general I can tell you the limiting factor is usually when some goes out of a linear region. Sometimes that is the base emitter junction. Sometimes this is when the transistor saturated or completely turn off during part of it's cycle.
This oscillator is complicated because it is taking advantage of phase-shift in the capacitors. The numbers are complex and can be very confusing.