[CW] 600 Hz Resonant Speaker for CW - Plans

[Jeffrey Herman]

Great. Well, if it was an April Fools article, I fell for it.

73, Jeff KH6O

PS: If anyone has an MFJ Morse Tutor you'd like to sell, please let me
know.



On Tue, 1 Sep 2009, Patrick wrote:

> Jeffrey Herman wrote:
> >  I seem to recall an article about a VERY narrow CW mechanical filter,
> > constructed as such: Take a pair of old headphone "cans", remove the
> > outer plastic ear cover, then remove the metal diaphram. Using a metal
> > cutter called a nipper (?), trim the diaphram in such a way that, for
> > the most part, just a reed appears in the center (the longer the reed,
> > the lower its resonant frequency, and vice versa). Replace the diaphram
> > and cover. Now that particular earpiece will only pass signals whose
> > audio freq'y exactly matches the reed's resonant freq'y.
> >
> > One of those "ah-ha" type of simple but effective projects.
> >
> > 73, Jeff  KH6O
>
> This was from an article in the April 1976 QST. I think this was
> something for the April Fools issue as the author's name was "Tinh
> Ehres" (Tin Ears) with a call of WH0OP. I remember reading about it
> before I was a ham (an Elmer had given me a bunch of old QST's) back in
> the early 80's. I have the .pdf of it or if you are a member of the
> ARRL, you can do an article search. The title is "CW Super-Selectivity".
>
> Patrick KA4ZNU
>
>
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