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TransAtlantic
QSO on LF completed |
ed: Talk about slowwww CW. Read this record breaking article.
Ottawa based amateur ham Larry Kayser, VA3LK and Laurie Mayhead,
G3AQC On completed a TransAtlantic QSO between the UK and Eastern
Ontario on 136 kHz on February 19th, 2001.
The QSO began
February the 5th and was completed on February 19th with the reception
of VA3LK's report by G3AQC. The QSO was made using a visual
adaptation of Morse, 2/1 dash/dot ratio and using the visual signal
receiving program ARGO. If you look close at the ARGO display that
Larry supplied KWARC, you can see "AQC LK G" in this shot.
Larry told KWARC that this type of QSO is about as much fun to watch
as watching paint dry or baseball or golf. Larry said
the dits are 90 seconds long, while the dashes are 180 seconds in
length.
Larry and Laurie had agreed in advance to a "firewall"
between them for the duration of the QSO. All QSO information was
exchanged over LF radio. The QSO was of long duration. It included time
for antenna failures and repairs at VA3LK, the effort was however
continuous, VA3LK made 27 separate trips to his remote radio site.
The message exchange used was based on a QSO model offered by Mike
Dennison, G3XDV. Mike outlined the process in an email dated January 26
on the LF Reflector, the format used was very close to this model.
G3AQC Station description
Laurie's 136 Khz station consists of a phased locked loop exciter
driving a 1000W audio Amplifier, which can only manage 400W at this
frequency. The Ant. is a top loaded vertical 48ft high with 450 ft of
top load. This is not in one length but zig zags in order to cover as
much ground as possible. This fed via a transformer, loading coil and
variometer. There is an extensive ground radial system. The ant.
radiation resistance is about 0.06 ohms and the total loss resistance 38
ohms, so with my 400W I manage to radiate about 350mW. My receive
antennas are two large grounded loops switched into a pre-amp with BP
filter. The receivers are an ICOM 756PRO for normal CW and a Racal 1792
for QRSS. I use the ARGO spectral analysis program for viewing QRSS.
L.V.Mayhead, G3AQC.
The VA3LK Station
VA3LK operates from the site were his remote controlled
HF
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| The transmitter power supply is along the back wall, 0 to 100V DC at up to 50 amps but he doesn't use that much with the amp just to the left of Larry. The exciter and computer is spread out along the table with his remote HF station just out of site to the left and the LDE chirping station is just out of sight to the right. |
station is located. The LF transmitter consists of a DDS exciter from
David G0MRF, with software by Johan, SM6LKM. The exciter output is put
through a hard limiting buffer that is keyed in the power lead. The
amplifier is a much modified ex commercial unit from the UK Decca system
that was decommissioned at just the right time. For the duration of the
Trans Atlantic QSO the amplifier was running at 65 V DC at 10 to 12
Amps. The antenna is a 100-meter semi vertical wire to the top of a
240-ft self-supporting tower. The wire is pulled out from the side of
the tower by a rope anchored some 450 ft away from the tower. Extensive
ground radials were pulled into place during the fall of 2000. The
loading coil is approximately 2.1 millihenry. Computing resources used a
Pentium 166 with dual booting DOS/Win95.
Larry, VA3LK, thanks those who have helped with this project, including
my pre retirement employer Bell Canada for the use of the radio site for
my HF station and other research work.
The UK LF gang who struggled to transfer to me the lessons they had
learned about LF. Canadians from VO1 to VE3 and VE7 who worked through
the learning curve with me and last and most importantly my wife, Joyce,
VE3JAK, who put up with all this and me for the last year and a half.
(Thanks to Larry Kayser VA3LK)
and the RAC news service
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This
picture shows the antenna loading coil at the base of the 240 foot
tower, it will light a 40 watt fluorescent bulb at about 50 ft
away.
Larry feeds the verticle with about 19 metres of hardline. The coil is 15 inches in diameter and wound on two short pieces of plastic sewer pipe. Larry's dog is his constant friend and manages all who come near the site. |