"Uncle Peter" ) writes:
"Michael Black" wrote in message
...
=?iso-8859-1?B?Rm9y52FDZWx0YQ==?= ) writes:
Hello,

It depends on what you need. Don't forget that the first single signal
selectivity came to receivers in the thirties, via a single crystal
filter.
I'm suddenly blank about the name, but it was a balanced transformer
feeding a crystal on one side and a trimmer capacitor on the other.
You'd
trim out the crystal holder's capacitance with the trimmer.

Lamb? WAG.

Certainly it was described first by Lamb, or he actualy came up with
it, in that famous 1930's article about improving receivers. Basically a
phasing crystal filter, which I suddenly was blank about when I posted.
I'm not sure I've ever seen it called a "Lamb filter", though perhaps
if you go far enough back in the books, it was once called that.

Michael VE2BVW

Actually, it wasn't. Don't recognize the famous 1930's article you refer to,
but Lamb came up with the Lamb noise blanker. The principle of operation
being to turn off the IF strip while the noise pulse was present, the "hole"
being less noticeable and annoying than a huge noise spike. Walter Cady came
up with the single crystal filter in 1922. Incorporated in most superhets
during the years 1925 until the ladder, half lattice and full lattice
filters came along in the 60's.

W4ZCB