Gregg ) writes:
Behold, Michael Black scribed on tube chassis:


Collins mechanical filters were always costly. Surely some of it
is because they aren't simple to manufacture.

Heh, where's the overseas knockoffs?


Well there were other manufacturers who made mechanical filters in
the sixties. You'd see them in the Lafayette catalog, and mentioned
in reviews (though I've always wondered if some of those reviews got
it wrong, and they weren't mechanical filters). But they were never
commmon. They were cheaper than Collins filters, but I have no idea how
absolutely cheap they were for the time. I don't recall coming across
real specs in the old magazines, either. I also recall in recent years
that it was those other filters that used foam rubber inside, and by
now much of that has deteriorated.

Michael VE2BVW