I helped my CW hearing ability by making a long speaker
box which allowed the speaker element to slide up and down
the length of the box, changing the resonant pitch of the
box, which allows an audio "peaking" effect.
This has the effect of amplifying the cw sidetone at different
pitches and also increasing the S/N ratio. Usually, the QRN
gets lost in the longer travel up the wooden box.
Dave
N4DAG

"AndyS" wrote in message
oups.com...
Andy writes:

A recent thread from a ham with a hearing disability who was
looking for a way to make CW easier to copy caused me to
think about something I had seen that might help. I will try
to describe it...

The audio output was applied to an amplifier that had
an artificial "threshold", like putting diodes in SERIES with
the input so that no signal would reach the amplifier until
the total level was high enough to break down the diodes
......... only the threshold was more precise and not
"soft".............. easy to do with op amps.....

The audio was adjusted to the point where NO signal
would not produce and output and YES signal would
simply amplify and cause an output...

..... much like adjusting a relay to click in at a given
threshold....

Note that this does NOT increase the SNR because that
has to be measure with a signal, and when the signal is
present the noise is riding on top of it......

However it would produce more "abrupt" contrast between
YES signal and NO signal..... much like the FM quieting
phenomena that one of the posters in CW Remodulator
referred to.......

It might improve the ability to copy for someone with a
hearing disability..

I haven't tried it, but I can't see why it wouldn't help.

If a reader has built it up, or something similar, I would
appreciate hearing about it..... or possibly where the
original article describing it appeared.... I'm sure it was
either the ARRL handbook or an old issues of QST....

Just wanted to throw this in the mix. Good luck.

Andy W4OAH