In article , Mike Coslo
writes:

Fessenden first transmitted voice modulated spark in 1900. The reply to
the transmission was via telegraphy. In the ensuing years, there were
both spark and alternator telephony experiments. The spark had the
disadvantage of a nasty hissing component in the audio, and the
contemporary alternators were running at up to 10 kHz, not very
satisfactory, because they weren't all that much above voice frequencies.

As time went by, alternators were built that could run at much higher
frequencies.

The first two-way transatlantic telephony was performed in 1906 at a
frequency of around 88 kHz.

This is all in the historical record.

A few more points, Mike:

- The 1900 voice radio transmissions were the first, and were over a distance
of about a mile.

- By 1903, Fessenden had extended the distance to 50 miles

- By November 1906, Fessenden had set up stations on both sides of the Atlantic
and was conducting two-way voice transatlantic radio communication.

- The much-heralded Christmas Eve 1906 event was not the first voice
transmission, but rather the first *broadcast*, as it was meant for general
reception by anyone with a suitable receiver. This broadcast was repeated a
week later, on New Year's Eve.

- Fessenden was able to generate intelligible voice-modulated spark by using a
supply frequency above the audible range. However, he found that modulating an
alternator was a superior method.

- A few years ago, some Canadians built a replica of Fessenden's 1900
transmitter, and using a dummy load were able to get it to work. Recoridngs of
the resulting signal are online. While the audio quality is low, the voice is
intelligible.

Fessenden was a true genius, with over 500 patents in a variety of fields. In
my opinion, he is second in significance only to Edwin Howard Armstrong in the
development of modern radio.

73 de Jim, N2EY