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.
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72 / 73 / 3579,
Jeff KH6O
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