
380
multiplied, producing, at the output of the transistor, components at
the sum and difference of the two input frequencies. The difference
component is selected by the tuned transformer in the drain circuit
Fig. 21.6 One of several types of device which
can be used for frequency-changing—a
dual-insulated-gate f.e.t.
and is passed on to the i.f. amplifier for further amplification.
21.5 Conversion Conductance
The effectiveness of an ordinary amplifying or oscillating type of
transistor is, or can be, expressed as the mutual conductance, in
milliamps of signal current in the output circuit per volt of signal
applied at the input. In a frequency-changer ...