[CW] 600 Hz Resonant Speaker for CW - Plans

[DANNY DOUGLAS]

Is that another April Fools joke?  A machine to read
Morse code???

  I tore apart 3 headphones, trying to build a mechanical audio
filter, and never could get them right, since my left and right ears have 
different hearing losses.

HI
Danny Douglas
N7DC
ex WN5QMX ET2US WA5UKR ET3USA
SV0WPP VS6DD N7DC/YV5 G5CTB

All 2 years or more (except Novice)
Pls QSL direct, buro, or LOTW preferred,
I Do not use, but as a courtesy do upload to eQSL for
those who do.

Moderator
DXandTALK
http://groups.yahoo.com/group/DXandTalk
DXandTALK at YAHOOGROUPS.COM

Moderator
Digital_modes
http://groups.yahoo.com/group/digital_modes/?yguid=341090159

----- Original Message ----- 
From: "Sergio R Rubio" <srrkp4l at onelinkpr.net>
To: "CW Reflector" <cw at mailman.qth.net>
Sent: Wednesday, September 02, 2009 11:38 AM
Subject: Re: [CW] 600 Hz Resonant Speaker for CW - Plans


>I have a Morse Code Reader MFJ-461, with its 9-volt battery included and
> working OK, for sale. Please let me know.
>
> Sergio KP4L
> No. 1 Honor Roll
> FOC 1090
> ----- Original Message ----- 
> From: "Jeffrey Herman" <jeffreyh at hawaii.edu>
> To: <flymooney at gmail.com>; "CW Reflector" <cw at mailman.qth.net>
> Sent: Tuesday, September 01, 2009 7:17 PM
> Subject: Re: [CW] 600 Hz Resonant Speaker for CW - Plans
>
>
>> 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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