I am new to Ham but a multi-decade experienced technician. BUT What is a
"Mechanical" Collins filter? I know what they are used for but why are they
called Mechanical?

I get an image of a tiny squirrel running in a cage.....

Thanks,
Paul.

"Mike Andrews" wrote in message
...
Paul P wrote:
I am new to Ham but a multi-decade experienced technician. BUT What is a
"Mechanical" Collins filter? I know what they are used for but why are
they
called Mechanical?

I get an image of a tiny squirrel running in a cage.....

It's not quite like that.

But they do have moving parts, though not quite as you imagine them.

Put a transducer on one end of a can to convert signal into mechanical
motion. Have it drive a thin, stiff rod along the axis of the rod.
Along the rod, at regular intervals, solder or weld the edges of a few
(maybe as many as 5 or 6) discs of metal, so that the discs are all
concentric. Now solder or weld another thin, stiff rod to all the
discs, 180 degrees away from the first, and put its free end into
another transducer at the other end of the can; the second transducer
converts mechanical motion back into signal. The center frequency and
bandwidth are determined by mechanical properties of the discs.

Collins developed these as small, sharp filters with steep skirts,
relatively-good passband ripple, and tolerable loss.

See
http://www.rockwellcollins.com/about/additionalproducts/collinsfilters/page4667.html
for information on more modern mechanical filters as well as the old
"drumhead" filters I describe above.

A Google search on "collins mechanical filter" will produce a plethora
of useful hits, too.

73, de

--
Mike Andrews, W5EGO

Tired old sysadmin

Mike,

That makes totally sense. I never imagined a filter made up like that. But
it makes total sense when you see it. Now I am really curious.

Duh. I should have Googled it.

Thanks,
Paul
kb3lzp
www.ppinyot.com

Crystal and ceramic filters are also mechinical filters, since they depend
upon the mechanical resonance of the quartz or ceramic.

I recall that some of the radio companies have advertised that their radios
had mechanical filters, when in fact they had ceramic filters.

As mentioned in the latest Electric Radio, Zenith apparently developed the
mechanical filter but decided it was not that useful and abandoned the idea
a number of years before Collins revisited it.

Colin K7FM

COLIN LAMB wrote:

Crystal and ceramic filters are also mechinical filters, since they depend
upon the mechanical resonance of the quartz or ceramic.

I recall that some of the radio companies have advertised that their radios
had mechanical filters, when in fact they had ceramic filters.

As mentioned in the latest Electric Radio, Zenith apparently developed the
mechanical filter but decided it was not that useful and abandoned the idea
a number of years before Collins revisited it.

Colin K7FM


Well, it is a mechanical filter, just not the one you're thinking
about. A crystal filter is mechanical, as well, but its dishonest to
try to make people think they are getting a machined metal mechanical
filter.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida