Hi Dan,
The 1BCG transmitter was redesigned and rebuilt many times before and during
the Transatlantic Test. The transmitter as first built in early December was a
"self rectified A.C. self oscillator" design, but Armstrong was very
dissatisfied with the roughness of the transmitted signal. On 4 December it was
decided that the transmitter should be rebuilt as a Master Oscillator - Power
Amplifier" (MOPA) with a 2000 volt DC motor generator power supply. It wasn't
until the third day of the Tests (December 9) that the transmitter was fully
functional with an estimated 600 watts power output.
The diagram in my presentation represents the configuration of the transmitter
on the night of 11/12 December when the first transoceanic message by amateur
radio was sent by 1BCG and received by Godley in Scotland.
http://topbanddinner.com/page_presentations.html
Propagation was very poor and atmospheric QRN was very high after the night of
11/12 December, and Godley heard no further transatlantic signals. Out of
frustration and with only a few days remaining before Godley was scheduled to
depart from Scotland, another 2500 volt motor generator was rushed to 1BCG and
connected in series with the original motor generator, with 4500 volts now
applied to the PA. That configuration was used for the last few days of the
Transatlantic Test and during the next two weeks when 1BCG made two way QSOs
with every state of the union.
Last night someone asked when the first successful amateur two way
transatlantic QSO took place. The date was 17 November 1923 on 110 meters, a
two way QSO between 8AB in Paris amd 1MO in West Hartford, CT. Of course there
is much more to this story, you can read about it in its entirety in on page 9
of January 1924 QST magazine. Just search for: Transatlantic Amateur
Communication Accomplished! at:
http://www.arrl.org/arrl-periodicals-archive-search
It would be many years before two way transoceanic QSOs took place on 160
meters, for many years all of the effort was focused on opening transoceanic DX
on the higher frequencies, all the way up to 5 meters.
73
Frank
W3LPL
----- Original Message -----
From: "Dan Z" <k2ywe@yahoo.com>
To: "Frank Donovan" <donovanf@starpower.net>
Sent: Tuesday, March 19, 2013 1:50:01 AM
Subject: First Top Band Conterst
Nice job, Frank.
Ken didn't read my question:
"I noticed the diagram of the station showed a 2500 V generator, but you siad
they ran 4500 V. A bit of trickery to circumvent the power limitation?"
Dan Zeitlin - K2YWE
South Shore ARC - K3AU
Annapolis, Maryland
http://danzee.org
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Topband Reflector
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