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Vintage Radio

The turn of the 20th century marked the birth of radio but the techniques used were very different from the techniques of today (or even 20 years later). It was the beginning of the ?spark era?, with crude transmitters that relied on spark gaps and equally crude receivers.

By Rodney Champness, VK3UG

Click for larger image
A low-power spark gap transmitter from the early 1900s. The technology was crude by today's standards but signals from high-power transmitters could be received hundreds (and sometimes thousands) of kilometres away.

At the turn of the 20th century, radio or “wireless” (as it was known in those days) was very much in its infancy. Valves had not yet made their appearance and spark transmitters were the only transmitter format in existence.

Receivers started out with “solid state” detectors, coherers, galena crystal detectors and many other detectors of varying efficiency and ease (or was it difficulty?) of adjustment.

Wireless in the early 1900s was mostly used between ships and between ships and land stations. It was remarkable that in those early days, the receivers had no amplifiers at all and relied on the efficiency of the antenna, their tuned circuits and an earth to pick up signals. By using relatively high-powered spark transmitters, it was possible to receive signals hundreds and sometimes thousands of kilometres away.

If we were to connect a modern crystal set to a big antenna and an efficient earth like they did back in the early 1900s, we would obtain similar results. I know of a listener in Rockhampton who has listened to Radio Australia from Shepparton with a crystal set on 9MHz. The effective radiated power in that direction is of the order of five megawatts (5MW).

Spark era equipment

It is not often that you see genuine or even replica wireless equipment from the spark era. However, when I attended the 25th anniversary of the founding of the Historical Radio Society of Australia (HRSA), I came upon a display of just such equipment by Ian Johnston. Many collectors have very early crystal sets using galena crystals but few have equipment that pre-dates the common use of this type of detector in receivers.

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