"Richard Harrison" wrote in message
...
Brian Reay wrote:
"---dying to hear at what frequencies directional couplers suddenly
begin to exist."
It isn`t sudden.
They sure work at audio frequencies. In telephones, they are used to
prevent the user`s voice from overpowering the distant party`s voice in
the user`s ear. They are called hybrids.
Hybrids are also used to couple a 2-wire circuit which simultaneously
carries both directions of transmission with a 4-wire circuit consisting
of a transmit pair and a receive pair.
Best regards, Richard Harrison, KB5WZI
Thank you for that Richard but I think you missed the British sense of
humour (or humor) ;-)
--
Brian Reay
www.g8osn.org.uk
www.amateurradiotraining.org.uk
FP#898