On Tue, 14 Feb 2017, Michael A. Terrell wrote:

Foxs Mercantile wrote:
On 2/9/2017 2:08 PM, Michael Black wrote:
Collins used mechanical filters in their receivers, but not all
of them.

Collins introduced them in the 75A-4 and 51J-4 receivers back in
the early '50s.

Drake used a 50 KHz IF and tuned LC filters in their receivers up
until the mid '60s.

The alternative to Collins mechanical filters were multi-pole crystal
filters. Which was what everyone else was using.

One of the stranger things to come across was Henry Radio offered a
kit to install a Collins mechanical filter in the Drake 2B receiver.

Absolutely pointless, but it allowed you to win "dick waving" contests.


I recently saw a notice that Rockwell Collins has stopped production of
Mechanical Filters.


That's now at least a year old, maybe two. They'd continue to sell what
they had in stock, but that was it.

I think I mentioned that some Japanese company was making mechanical
filters in the sixties (word is that they had some foam in them that goes
bad over the decades), which showed up in Lafayette ham receivers and CB
sets, but for some reason, that didn't continue to be a source of
mechanical filters.

There wsa an article in CQ magazine in the early sixties where someone
described a receiver they built, and they even built the mechanical
filter. Not sure if they gave enough information to duplicate the filter
at home, or if anything too out of the ordinary was needed.

I think ceramic filters took care of the cheap mechanical filters, leaving
COllins for the really good receivers.

Michael