[R-1051] R-1051 Speakers

[Jim Haynes]

On Thu, 12 Dec 2019, David I. Emery wrote:

> On Thu, Nov 21, 2019 at 10:17:52AM -0500, paul swed wrote:
>
> 	FWIW it is also notable that - internally in telco plant -
> similar carrier telegraph circuits on voice grade channels were used as
> long ago as the 1930s though some of these were AM (OOK) rather than
> FSK.  And before that WU and other telegraph companies used various
> similar audio FDM multiplexing as well as the more common TDM on
> various telegraph lines.

I recall reading that one of the problems WU had in going to FDM was
that so many of their open wire lines were ground-return telegraph
circuits, so it was hard to find a pair of wires that could be used
for a voice-grade circuit.  Also that Postal Telegraph had originally
built their lines to be voice grade because they expected to use the
early FDM "harmonic telegraph" that Elisha Gray and A.G.Bell were
experimenting with in the early days.

I forget what this has to do with R-1051s.

Jim W6JVE