Re: Grid Dip Oscillator

To: "'Tesla List'" <tesla-at-poodle.pupman-dot-com>
Subject: Re: Grid Dip Oscillator
From: Tesla List <tesla-at-stic-dot-net>
Date: Fri, 21 Nov 1997 22:41:32 -0600
Approved: tesla-at-stic-dot-net


From: 	Edward V. Phillips[SMTP:ed-at-alumni.caltech.edu]
Sent: 	Friday, November 21, 1997 1:43 PM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: Grid Dip Oscillator

"I was looking through the first issue of "On The Air!" magazine, a
magazine for ham radio, and saw an article on building a device called a
grid dip oscillator(or a drain dip oscillator).  Has anyone any experience
with these?"
	Sure.  Very handy gadget for measuring the resonant 
frequency of tuned circuits.  The principle of operation is
simple:  the oscillator inductance is brought close to the
circuit under test, and the frequency varied.  When the resonant
frequency is reached power will couple from the oscillator to
the circuit, with resultant increase in loss and reduction of
feedback voltage, which affects the plate/drain/collector
current.  Good from a few kHz to microwave, provided you have
the right tuning inductor.  Keep the L/C ratio of the tank
relatively high for best results.
	Such gadgets have been around since the '20's, and
you will find references in many of the old "radio" books and
magazines.

Ed