[HCDX] AUSTRALIA-UK BEAM WIRELESS 75TH ANNIVERSARY - UPDATE

["Bob Padula" <bobpadula@xxxxxxxxxxxxx>]

BEAM WIRELESS ANNIVERSARY. The story about our 75th anniversary visit to
the historical site at Ballan (Victoria) which was once used for
Australia's first commercial beam wireless transmitting station was
included this week in the Moorabbin and District Radio Club's weekly
broadcast "APC news" and also distributed via E-mail to the YahooGroups
list.

As we mentioned, the fist broadcast from Fiskville in April 1927 was
probably the most important event in the development of commercial HF
radio in Australia.

Some further information has come to hand from researching of material
at the Melbourne Pubic Library, which may be of interest!

At its inception, the station used two 25 kW transmitters, with the
calllsigns VIZ and VIY. A third transmitter was added at a later stage,
and the station continued broadcast high-speed telegraphy until its
closure in 1969. In its later years, it was used also for carrying
scanned "radio pictures".

The receiving station was a few km away, at Rockbank.

One transmitter and antenna was used for broadcasting to the UK - the
other for Canada. The English stations were located at Grimsby
(transmitter) and Skegness (receiver). The transmitting station in
Canada was at Drummondville, and at Yamachiche, for the receiver.

The Ballan station used three towers to support two curtain antennas
with reflectors. Each transmitter consisted of a three-stage power
amplifier, driven by a master oscillator. The transmitters were keyed
from a control room in the Melbourne Central business district (Queen
Street), via "landlines". Plate voltage was a mere 20,000 Volts!

Transmission speeds of up to 2000 words per minute were achieved, using
automated signalling, and controlled by punched tape.

Commercial (mains) power was not connected to the Ballan site until
1941, and prior to that, power was generated locally by three 165 HP
oil-engines coupled to direct-current dynamos. One generator supplied
filament power, presumed to be AC. There were no batteries.

The receiving station at Rockbank also had three antenna masts, with two
16 HP oil engines for power, coupled to 110 Volts, 90 Amp DC generators,
which were used to charge a bank of accumumators. The bank consisted of
60 230 amp-hour accumulators. There were two additional generator sets -
one to charge the "A" batteries, the other for the "B" batteries. The
"B" battery generator delivered 6 Amps at 300 Volts.

The actual operating frequency appeared to be around 12 MHz, for both
transmitters, and output would have been a form of "narrowband" CW.

Incoming signals were converted to 8 kHz, and then modulated to a 1 kHz
audio tone, and then sent on their way to the control centre via
telephone lines.

The Ballan station was huge by the standards of the day, and the antenna
towers were visible up to many km across the surrounding plains.

The technology was the best available at the time, and was the first
commercial exploitation of HF DX work! The system was not designed for
voice, and it's interesting to recall that the first HF voice
transmission from Victoria was later in 1927, from a transmitter
co-located at the site of the original 3LO mediumwave station, in the
western suburb of Braybrook. This transmitter also operated around 12
MHz, and was very similar in design to the Ballan CW station, with the
addition of a modulator. This transmitter took the callsign VK3ME and
continued to operate (along with a sister station in Sydney - VK2ME) -
until the start of World War 11, when it was taken over by the
Government.

The Amalgamated Wireless of Australia company (AWA) was responsible for
setting up the Ballan, Rockbank, and Braybrook stations.

A little bit of history, there!

Regards

Bob Padula, Surrey Hills, Victoria, Australia



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