On Fri, 24 Jan 2014, dave wrote:

On 01/23/2014 06:05 PM, Michael A. Terrell wrote:

dave wrote:

On 01/23/2014 06:45 AM, Michael A. Terrell wrote:


It is not a switch or a valve.


It's a solid state diode that oscillates. DC in, and ~10 GHZ out.
Search on Gunnplexer. You see them on automatic doors in almost every
store. A microwave mixer diode takes a sample from the Gunn diode and
compares it to any reflected signals. This results in a low frequency
signal that is detected, amplified and signals the door to open. How can
a passive diode do that?


Like I said. You can hit a piece of quartz with a hammer and it will
oscillate; that doesn't mean it's considered and active device. An active
device uses one signal [current, voltage] to control another. As in amplify
or switch. Thermionic valve, transistor, SCR, Triac is what we are going for.


I can't keep track of this argument.

But, that piece of quartz, the output will start decaying in volume almost
immediately. It requires an active device to keep that going.

Michael