Chris Albertson wrote:
I want to get set up to make accurate frequency stability measurements
at reasonable cost. I think mixers are the way to do that. I'll set
up a single mixer first them later learn to use the double mixer
technique. But I will use the simpler single mixer to try out the
parts. My goal is a multi-channel double mixer setup.
First question: Which type of mixers work best for this. I have
some SA612 chips in the parts bin. Or should I be using diodes or
something else. Yes I know I could simply buy one from Mini Circuits
but that defeats the purpose which is learning how to do this
2nd question. if the device under test is a square wave oscillator is
it best to run the square wave right into a mixer or filter them to
sine waves first. I see pros and cons of each. What do the experts
do?
Diode mixers (or perhaps, for low frequencies (5-20MHz) a diode style
mixer <http://tf.boulder.nist.gov/general/pdf/2556.pdf> using diode
connected (collector base short) 2N2222's as recently espoused by NIST)
have far lower phase noise than other mixer types.
This paper also has a plot that illustrates the noise performance of
this custom mixer compared to a couple of conventional diode mixers.
Running the mixers in saturated mode lowers the phase noise compared to
linear mode operation.
Bruce
_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
