[CW] CW headphones

[Chris R. NW6V]

Hi Jeff.

Mechanical acoustic filters work great.

Modern radios often contain the electronic equivalent - my K3, for example,
has brilliant AF filtering—no way I could have made 80 M DXCC from this
noisy city QTH without it.

But I LOVE the idea of resonating to a harmonic reed... just LOVE it :-)

73 Chris NW6V

On Wed, Feb 11, 2026 at 10:00 AM Radio KH6O <radio.kh6o at gmail.com> wrote:

> I'm enjoying the CW acoustic speaker discussion on the Topband list but
> here's an entirely different idea: I was a US Coast Guard radioman back in
> the 70s when almost all maritime traffic was conducted in Morse. We were
> issued government headphones that had a metal diaphragm held in place with
> a magnet.
>
> A colleague used a pair of metal cutters to cut out a small
> rectangular area from the diaphragm and riveted a reed from a harmonica in
> its place, then reassembled everything. Adjusting the receiver BFO to match
> the reed's frequency resulted in that reed acting as an incredibly sharp
> and narrow bandwidth filter.
>
> Pretty soon we were all bringing harmonicas to the station and removing
> our favorite musical frequency reed to do the modification! This really
> helped clear the pile ups on the HF maritime frequencies during the
> every-six-hour weather OBS from the ships. (Ham pile ups are nothing
> compared to what we encountered!)
>
> Today's headphones no longer have metal discs so some other method would
> have to be employed to implement this idea.
>
> Station name: US Coast Guard Communication Station Honolulu, callsign NMO.
>
> --
>
> 72 / 73 / 3579,
> Jeff KH6O
>
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> =30=
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