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Introduction
Simple dowconverter for Meteosat receiving is described in
this article. The main advantage is that you downconverter
doesn't contain the chain of multipliers and you need only
digital multimeter to adjust it. The downconverter doesn't
contain winded coils and all filters are notune made on PCB.
Converter has low noise figure and high gain. The minimum
usable dish size is 60cm. You can use this downconverter
with small antenna, with common 144MHz transceiver allowed
WBFM mode, with PC sound card and new program JVcomm32.
I use YAESU FT-50. These facts could approach weather
pictures from sky to wide group of radio listeners. At the
end of this article reader will find inspiration how to make
this downconverter more cheaper and easier with new
Motorola's RF components.
The
system of weather satellites was explained in lot of
literature. The most interesting satellites for weather
prediction are geostacionary ones. Meteosat 7, usable in
Europe, transmits WEFAX data on two channels on 1691 MHz and
on 1694.5MHz. If you want to use common receiver for FM
"meteo" band you need to convert signal from 1691
MHz to 137.5 - 141 MHz. This is work of downconverter...
Basic description of technical parameters of
converter:
| Module input
frequency:
|
1691
- 1694,5 MHz |
| Module output
frequency:
|
137,5
( altern. 155,0 or 58,7) MHz |
| Power
supply:
|
DC 9 - 12 V
(from receiver's input)
|
|
Current consumption:
|
270
mA, PTC temperature stabilisation
|
|
Noise number: |
<
1.5
dB |
| Gain:
|
40
dB |
| Input VF
connector:
|
BNC
Fem. |
| Output VF
connector:
|
BNC
Fem. |
| Module
dimensions: |
95x70x25
mm |
Connections side diagram of converter printed
circuit...
Component side diagram of converter printed circuit...
In conclusion we solder thermostat according to picture:
Place the quartz horizontally, pass strip of insulating tube over it
and slip under it a target of PTC thermistor. Solder the quartz case
to the earthing foil, by which you will connect one contact of
thermistor.
Picture on the left shows procedure for assembly of thermostat for the
quartz 24,274437 MHz with use of PTC thermistor and a shrink-wrap
insulating tube. Picture on the right shows how to build it into the
converter and connect to the power supply of +12 volts...
Further
Pictures
The
Art of Improvising... (receiving Meteosat 7 ... , no problem :-)
As you can see at the last two photos, it is possible to receive
signals from the satellite METEOSAT 7 with use of the described
converter even behind the window with double glass on parabolic
antenna with diameter of 60 cm and without pre-amplifier.
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