[Amps] al-1500 parasitic?? or some other problem?

[Steve Thompson]

-----Original Message-----
From: jeff millar <wa1hco@adelphia.net>
To: David Robbins <k1ttt@arrl.net>
Cc: 'Amps' <amps@contesting.com>
Date: 15 May 2002 07:15
Subject: Re: [Amps] al-1500 parasitic?? or some other problem?


>It's possible to generate a 1.5x multiplier with a nonlinear C or L.  I
once
>designed a 144 to 226 multplier with a varactor diode and some tuned
>circuits.  The circuit contained an idler tuned circuit at 1/2 input, which
>mixed with the input to generate 1.5x.  Some literature exists for non
>integer varactor multiplers...but they never became popular, too touchy and
>unstable.
>
>Another way weird things can happen with "pumped" nonlinear C (or L); they
>can look like a negative resistance.  Parametric amplifiers use that
>technique.  Feed RF power into a nonlinear resonant circuit, usually a
>microwave cavity with varactor, but possibly an HF tank with overloaded
>ferrites...then feed the signal of interest into the resonant circuit,
which
>reflects back with power gain (a line terminated with negative resistance
>reflects more power that applied).  If you have nonlinearities in the
>magnetics, it can create parametric amplification/oscillation...possibly
>injection locked to the pump frequency.
The collector base capacitor in a power bipolar makes a good varactor to
provide the non linear element.

Steve