wrote in message
...
On Tue, 7 Feb 2017 16:11:28 -0500, Michael Black wrote:

There are stories of Collins receivers, I forget which model, where the
capacitor feeding the mechanical filter can go bad, and the result is
a ruined mechanical filter, it can't handle the DC going through it.

SO that's the sort of thing knowledge that is out there for people coming
to an old receiver for the first time.

Michael


What is a " mechanical filter"?

Pretty much what the name says it is.

Usually a row of disks with a mechanical resonant frequency, AFAIK: the
transducers at each end were usually inductive, but I believe there were
piezo types.

At one time they were the most common type of IF selectivity in Ham radio
and other communications gear.