The inductor keeps the transistor base at DC ground potential (probably the
same potential as the not-shown emitter). This makes the transistor only
conduct on positive half-cycles of the drive signal, which is a very
non-linear condition that generates lot's of harmonic content. It's also
common to put a little resistance in series with the inductor, which
slightly reverse-biases the transistor because the RF waveform can then
swing more toward the negative than the positive. A little reverse bias
causes the transistor to conduct over a smaller portion of the input cycle,
which enhances higher-order harmonic generation.

Joe
W3JDR

Steve Evans wrote in message
...
Hi everyone,

Below you will find my attempt to show in text-form, a circuit
fragment from a 145Mhz amplifier:


--------------capacitor-------------------------------transistor base
|
|
I
|
coil
|
|
|
|
------------------------------------------------------------GND

The cap's value is 1nF; the inductor's is 0.4uH.
The cap (I assume) is to couple one amplifier stage into the next
(50ohm source/load) with minimal attenuation of the desired VHF
signal. But like what's the purpose of this inductor to ground??


--

Fat, sugar, salt, beer: the four essentials for a healthy diet.