Hello Stefan,
A great moment as the radio with
a kite antenna!
The story of this kite is quite
special (actually there are 2: one of 4m² and another of
6m²), at the beginning it was intended to make
manipulations and tests on active payload of satellites,
(I am also member of the AMSAT- France).
Pareafter I was
contaminated (thank you F6AGR!;-)) by the
low bands ...
Having had the chance to retrieve carbon fiber rods
for the construction of Ariane 4 (9m long!), We decided
to use them to make kites to test our payloads, balloons
and satellites (and even to drop sweets in regional
events ...!).
In short these machines are only a
"tractors"!
During a demonstration
(ASTRORADIO 2005, the "small" served as support for an
aluminum wire (1.6mm) of ~ 150m to 200m
Some
pictures here: http://lastroradio.free.fr/Astroradio2005/Album11.htm
The
difficulty of the kite is especially the takeoff in
order to capture as soon as possible the good windy zone
(not always easy in the middle of June!), But after that
it goes ...
I do not speak also
of the difficulties to pick up the wire when it falls
with the kite in a field of corn! (You have to love the
RADIO!)
The problem of the
demonstration ASTRORADIO was the reception, we were
not the only ones to make the emission and a
transmitter of 500W on 14 MHz within 100m of the LF
station ... Not simple ... Too bad!
Now, I'm all alone to do LF (and no more
young), so it goes slower ...
The main difficulty here (I am in Normandy,
near the sea, where there is wind!) Is to find
charitable souls able to share my tastes for "curious"
things like the LF / VLF. It's long
and you have to make concessions, but over time ...
It's starting to become concrete!
I have several fields to grow
antennas beverage, K9AY, and of course kite! But to this is added some
difficulties such as energy and housing that are
about to be resolved. Camping in the middle of winter is a
bit hard for my old bones ...
On the power stage side,
I'm thinking of a power MOS-based amplifier with
IXYS IXFH94N30 at liquid-cooled IXYS (water +
glycol), with the primary cooler out and the heat up
(winter is good sometimes).
The transformers are
mounted on welder station ferrites (nominal
frequency ~ 100 KHz, a good choice of manufacturers,
thanks!) The "high voltage" power supply provided by
two 51V 57 A server power supplies (HP EPS120) compatible with a capricious
generator! (I
think he's allergic to CW!)
Half a branch of the PWR RF
bridge
during construction
The
MOS (uninsulated, so the Drain) are directly placed
on the cold plate which itself is connected to the
primary of the transformer. Possible thing with
liquid cooling.
There is thus twice this assembly, one by branch and
the transformer in the middle, it is more compact!
I will try to find other photographs, now everything
is in the box, it is no longer readable so ...
The external cooler is regulated by a turbine, all
enslaved by a CTN placed on the radiator (vehicle
interior heating radiator recovered in a flea
market) Two turbines of 2000 liter per minute at
variable speed therefore controlled by a simple PID
driven by the CTN.
The turbines (EBM D1G133-BF17-15 40 to 60V DC) are
GSM station recovery, their speed control being done
by a voltage of 0 to 10V (easy to control so with
simple OAP)
My current problem, find a dummy load able to hold
the power (I already grilled 2 CANTENA!), The QRSS
is naughty!
There is
still the problem of the final coil and especially the
variometer (mechanical and servocontrol all compatible
with a winter weather, rain snow, overloads like the kite
on the ground.It must cut the transmission otherwise there
is risk to find each other in the
television news of the next day under the miscellaneous
heading!)
I should preferably use the small kite, the
large (6m²) is really too strong, the pulling force is
difficult to control even changing the angle of attack, I
have already broken several times of the aluminum wire
1.8mm (and find in the middle of the night a
kite ground very far in the rain is not compatible with my
mood!)
Picture of Ko NL9222 (a very good
SWL!)
In the words of James M0BMU June 18, 2005,
our signal at home was more than respectable, it's a
good start encouraging!
To be continued ... And live the LF!
VY 73'S: Jeff
Le 13/07/2018 à 08:01, DK7FC a
écrit :
Hello Jeff,
Am 12.07.2018 22:21, schrieb F6CWN:
It's a
pleasure when it works!
My experience balloon and
kite (Spountnik loads tests a few years ago,
launched since MIR, a great thing too!): Do not
use plastic wrapped wire (static electricity,
several KV!).
Do not forget a resistance
(~ 500 K Ohms 2W) between the antenna and the
ground otherwise it is very unpleasant! (Hi!)
I hope to contact you this
winter, here I use a kite (6m ²) and aluminum wire
(1.6 or 0.8mm diameter). Tests have been done on 160m and it works
very well, I hope to reproduce these tests on 136
KHz (QRSS and normal CW), always with a kite
(helium and the balloon are too expensive for me).
VY 73 Alex and thank you
again for the report.
Great! I'm looking forward to your signal. Some years ago i
also worked with kite antennas on LF and VLF. In the first
experiments i've built e.g. a J-antenna for 160m, i.e. a 82m
vertical wire and a transformer cable to transform to 50 Ohm.
A used a call-E PA running 600 W at 160m. The PA worked at 36
V (using 4x IRFP 260N), 3 car batteries switched in series :-)
It was all portable and i had CW QSOs with Japan on 160m m at
lower power levels :-)
Great great great times!
What type of kite are you using for your experiments?
Good luck to all kite transmitting stations :-)
73, Stefan
