Two nearby ASOS broadcasts on the same frequency: Why no squeal?

"RST Engineering" wrote

Having said that, since power consumption for a ground station is not a
primary concern, you can put the electronic device that controls frequency
into a temperature chamber (crystal oven) and expect that day in and day
out
it will be within a few Hz. of where it was originally set.

Is this still commonly done today? What is a crystal oven, how big, and how
is the temperature regulated?

What? (wha) I (wha) can't (wha) hear (wha) you! (wha) g
--
Jim in NC

Oh, it is common and fairly easy. You simply say, "the temperature here
will never exceed (some number say) 60d C. You then calculate the
parameters for the crystal oven for a fair margin of error (say, 65d C)

The crystal is about the size of two dimes held face to face. The oven is
about the size of four quarters held face to face with a cutout in the
middle to accept the crystal. On one side of the face of the quarters is a
fairly large resistor (1-5 watts) bonded with thermal epoxy to the face of
the outside quarter. On the opposite face is the temperature sensor,
similarly bonded to the quarter (thermistor or diode; I prefer diodes)

A controllable heater heats the resistor. When the temperature of the
quarters exceeds the temperature set of the thermistor/diode, the heater
shuts off. It is a bang-bang servo. There are a THOUSAND refinements that
you all can have.


Is this still commonly done today? What is a crystal oven, how big, and
how
is the temperature regulated?


Jim

"RST Engineering" wrote

Oh, it is common and fairly easy. You simply say, "the temperature here
will never exceed (some number say) 60d C. You then calculate the
parameters for the crystal oven for a fair margin of error (say, 65d C)

Who'uda thunk I'd learn something new today, when I got up? Not me, and not
here! g

Thanks! (I bet that makes yur life wurth liv'n) ;-))
--
Jim in NC