Dear all,
in Munich we were sparking the "soft way":
During a speech by DJ3YB about the development of radio I had the chance to
demonstrate a spark transmitter simulator constructed already in the eighties:
Two gates of a CMOS 4093B form an RC oscillator which can be tuned by a potentiometer from 200 Hz to 1 kHz, a third gate is keying this oscillator, and the fourth gate is amplifying the rectangular wave form, the slopes of which are pushing (via 22 pF) an LC circuit tunable from 1,8 to 3,6 MHz, with an output link to 50 ohms, thus simulating the spark transmitter as a high-grade frequency multiplier.
The power is just sufficient to generate S9 in a R1000 receiver in AM. But by tuning the potentiometer through its range it is possible to demonstrate the sound of different kinds of spark transmitters, from the krrk krrk sound of a Marconi spark up to the tone sound spark pioneered by Telefunken in the following years.
For better understanding a drawing of the Telefunken multiple spark gap has
been displayed on the wall to discuss the way how this construction would
enable a spark repetition rate of up to 1 kHz, generating a sound that could be
copied much better in noise and qrn (all history now, of course, but a
remarkable difference in those spark years).
From the same QTH the club station of the German Museum in Munich, DL 0 DM, had
been active in CW only with usual amateur equipment, with up to 300 QSOs
counted up to the early evening, contacting several other memorial stations.
After returning home there was still time to copy the Marconi memorial
transmission of DDH47 on 147,3 kHz at 22.30 gmt.
73 Ha-Jo, DJ1ZB
"Ko Versteeg" <[email protected]> schrieb:
The sound of a spark transmitter was heard once again on an amateur
band to mark the centennial of Guglielmo Marconi's first
transatlantic radio success. It was 100 years ago, on December 12,
1901, that Marconi--at his receiving station in Newfoundland--copied
the three dits of the Morse letter ''S'' transmitted from 2000 miles
away in Cornwall, England. An Amateur Radio on the International
Space Station (ARISS) contact with students in Newfoundland also was
successfully completed.
David Wilson, VE3BBN, near Niagara Falls, Ontario, built a low-power
rotary spark transmitter and had permission from Industry Canada to
use it December 12 from 9 to 10 PM Eastern Time (0200-0300 December
13 UTC). The operating frequency was approximately 3550 kHz.
Wilson says the transmitter has a bandwidth of 20 kHz, and AM mode
reception with a wide IF bandwidth works best. He transmitted
''MARCONI S'' every minute during the one-hour period.
''This is a very low-powered transmitter with 10 W spread over 20 kHz
(3-dB points) and having very broad skirts,'' he said. He said the
spark signal is highly unlikely to interfere with normal amateur
operations, but a test signal was copied at distances of at least
250 km (approximately 155 miles). Wilson used an 80-meter Windom
antenna.
VE3BBN invites signal reports via e-mail, David Wilson, VE3BBN,
[email protected].
An Amateur Radio on the International Space Station contact December
12 between Frank Culbertson, KD5OPQ--operating NA1SS on the ISS--and
students at the Marconi site in Newfoundland also marked the Marconi
transatlantic centennial. During the contact between NA1SS and
Marconi Radio Project special event station VO1S, 10 students got to
quiz Culbertson about life in space. Culbertson is completing his
tour of duty aboard the ISS this week. The ninth-grade students were
winners of a crystal-set building competition associated with the
centennial observance.
The contact was arranged with the assistance of Memorial University
of Newfoundland, The Institute of Electrical and Electronics
Engineers, and the Society of Newfoundland Radio Amateurs.
73 Ko, NL9222
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