Croix
d'Hins
radiotelegraphic
station
History notes (part 2)
The
buildings.
The station
site includes in addition to the main building
a general
warehouse, techninal building, restaurant building,
coal
storage
and locomotive garage, personnel buildings (4),
school,
Station chief house ("the white house"), energy station,
water
reservoir, garage, gas, pumps room, wood warehouse.
The main
building is 76m long, 16m wide and 11m high. It is
divided
into five machines-rooms. The railway enters in it.
More rooms
were added after 1938.
When
building
the parts of main building close to radio
equipment,
no metal piece was used (including for doors on
whatever.
nuts,
door handles ... etc) or would be grounded
to
avoid heating.
After 1938
a new room was built for new high power lamp
transmitter
(callsign FYP).
And in
1939 another one was built for lamp-tx shortwave transmitters.
During
1939 was built a new cooling water reservoir and new pumps
rooms.
The water temperature would be at 25 C in all seasons
(dissipating
about
100 kW) and staff could swim in it ,although
not
officially
autorised.
The
antenna
is made of 16 horizontal wires carried by
the eight
250m towers (four towers on each side).
The area
of this horizontal part is 400 meters x 1200 meters.
Then ten
wires go down vertically into the main building
to the
antenna coil. This vertical part is actually the
active
part of the antenna
The
antenna
coil is 5 to 6 meters high and same diameter.
With the
horizontal capacitive part and the ground, the coil
constitute
the tuned circuit.
Wavelenghts
are between 19150 meters to 23450 meters.
The gound
system was first a copper plate with an area
of 200
square meters burried at 50 centimeters and connected
to 100
vertical 14-meters-long copper tubes into the ground.
Then was
added a network of 60 kilometers of copper wire
burried
under the antenna. (you still find some today in the
ground)
The spark
transmitter : 1920 to 1923
It is
built by FEDERAL TELEGRAPH Co.. There are two transmitters
in Croix
d'Hins, one is a backup.
Normal
spark power is 1000 kW and the yield to change DC
to AC
is about 50% leading to 500 kW HF.
The spark
is fed under 1250 volts and 800 Amperes.
Its weight
is 80 tons, 70 tons being for the magnetic circuit.
That huge
cover is 2.8 meters high. Its primary coils is
in series
with the spark and has the 800 Amperes. It is
immerged
into oil cooled by the water circuit, pumps and
external
reservoir. The magnetic field reaches 17000 Gauss.
Visitor's
watches would often be damaged. Heavy metal pieces
lifted
more than one meter from the cover would not fall
down but
would stick to it.
Spark
anode is a copper tube one centimeter diameter cooled
by water.
Cathode is made of carbon, 4 centimeters diameter
and 50
centimeters initial length. It is replaced every 24 hours.
It is
rotating for a regular erosion.
The spark
chamber has an atmosphere of alcohol and petroleum
(falling
drop by drop) to improve efficiency. (20 liters / 24H)
The 1250
volts / 800 amps are obtained from a 1000 kW converter
group
working under 2200 volts AC coming from the energy building
final
transformer.
Stabilized
spark results in one frequency being transmitted.
Morse
modulation is obtained by frequency shift.
The
frequency
shift is obtained by short-circuiting one
loop in
the antenna coil (actually not one of the real
loops
but 78 smaller loops simultaneously short-circuited.
The 78
breakers have silver terminals. They are fed by a
20 kW
generator.
The spark transmitter callsign is : LY
Up to 27
harmonics have been found to be generated and
these
transmitters are causing troubles to others and to
the newly
introduced radio broadcasting.
From 1923,
spark transmitter is kept as backup but replaced
by new
HF generator, type Bethenod-Latour.
(patent
by Marius Latour, 1917)
The output
power is 500 kW with a 84 percent yield.
Its single
HF output wavelength is 19150 meters.
Its
callsign
is : FYL
Return
to
first part
Go
to
Part 3
Other references :(thanks Al Heiden, Don Kimberlin)
- See a description of the station from an online version of "History
of communications-Electronics in the United States Navy".
at : http://www.angelfire.com/nc2/whitetho/1963hw20.htm#20sec6
(local
copy)
The History of NSS, Annapolis, Maryland : http://members.aol.com/k6dc/history.htm
The Telegraph Office :
http://www.metronet.com/~nmcewen/Federal_Telegraph_Relay.html
George T. Royden oral history :
http://www.ieee.org/organizations/history_center/oral_histories/transcripts/royden10.html
The Passing of A Pioneer :
http://antiqueradios.com/pioneer.shtml
Page by Pierre Dessapt :
http://perso.club-internet.fr/dspt
Jurassic Telecommunication :
http://www.oldradio.com/archives/jurassic/
Don Kimberlin's page :
http://members.fortunecity.com/donkimberlin
Informations or documents about Lafayette Station are welcome at : eric.tiffon@freesbee.fr
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