[Elecraft] Binaural CW tuning

[Geoffrey Mackenzie-Kennedy]

 Bart PA3GUY wrote:

> This has been on my mind too for a long time. I even seem to recall I've 
> got a schematic saved somewhere for a circuit that does just that, so 
> somebody beat us to it. I just never came around to built and test it for 
> myself.... For details, contact me offline and I'll try to dig up the 
> circuit.
>
> I'd expect the hiss that 'll always appear in one ear to cause fatigue.
>
> Anybody 'been there, done that' and willing to tell us about it?

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 Back in 1973, G3OTK suggested a high pass - low pass filter scheme to 
obtain
 a pseudo-stereo effect for binaural reception, and I believe that his
 filters 'crossed over' at 500Hz.  I would agree that something would have 
to
 be done about hiss coming from the 'high frequency' channel, but it might
 have to be something more clever than just adding a low pass 'hiss 
filter' -
 I don't know.

 PA0CX came up with a very interesting scheme in 1958 named
 'Frequencieschaar' which split a double sideband AM signal into two halves
 so that a pseudo-stereo audio output could be obtained. This helped to
 overcome the problems of selective fading and QRM. Also in Chapter 9 of
 'Experimental Methods in RF Design' by W7ZOI, KK7B and W7PUA there is an
 example of a simple binaural receiver taken from QST, March 1999.

 Personally I like to use binaural reception. Why is difficult to explain,
 but the effect is like being 'inside' the band with signals on each side
 which helps the a lot when trying to listen to one signal amongst the QRM.

 73,
Geoff
GM4ESD