> Don,
You have it right; the correct term is "microphonics." The IEEE Standard
Dictionary of Electrical and Electronics
Terms defines microphonics as "The noise caused by mechanical shock or
vibration of elements in a system."
Tube-type amplifiers are extremely prone to microphonics, since they have grids
and plates that can be vibrated
easily. Solid-state devices are much less prone.
IMHO, the most frequent culprit of microphonics in recent radio equipment is
the thin aluminum shield can over a
frequency-determining coil/capacitor combination. Vibration at an audio rate-
such as a human voice- may vibrate the
thin shield enough to affect the capacitance to ground of the enclosed tuned
circuit and lead to modulation of the RF
within. Total encapsulation with wax or epoxy usually corrects this effect,
but it makes it difficult to tune the
circuit later.
73, Eric Lemmon WB6FLY
>
> ----- Original Message -----
> From: "Don" <[EMAIL PROTECTED]>
>
> What is the best way to try and eliminate exciter micro phonics? it is
> a Hamtronics T-301 220 exciter, enclosed in a tight aluminum case. If you
> touch the case, etc., and even the
> little muffin fan, vib will generate noise
> heard on the transmit audio. Also, this is the exciter that I'm trying to
> get a data sheet on the Philips BFQ-43S
> transistor with no luck yet
>
> P. S. What is the technical term for micro phonics?
>
> Thanks Don KA9QJG
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