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The WSE RX70 is a converter that converts two radio frequency signals at
70 MHz to 10.7 MHz.
The WSE RX70 is designed for use together with the WSE RX10700 and the
WSE RX2500 as a part of a receiver for the amateur radio bands.
The WSE RX70 contains five crystals. Together with the four crystals in
the WSE RX10700 unit, this allows 20 frequency combinations.
The center frequency can be set to one of the following: 69.975 MHz,
70.000 MHz, 70.025 MHz ..........70.450 MHz.
This way the frequency coverage is extended from the 93 kHz obtainable
at 2.5 MHz with the RX2500 to 568 kHz at 70 MHz.
The RX70 is intended to be the first IF of a receiver system.
Other converters convert from amateur bands to 70 MHz in 0.5 MHz wide
segments.
The WSE RX70 was sold in the years 2002 to 2010 in a quantity of
about 50 units for a price of 2920 SEK excluding VAT.
The WSE project is now closed but there is some left-over from the
project that we offer here:
WSE surplus
WSE RX70 technical data
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Input
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Two BNC connectors for two receive channels.
Nominal input impedance 50 ohms.
SWR < 2 for frequencies between 69.5 and 71.0 MHz.
Maximum input RF power +25 dBm.
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Output
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Two BNC connectors for two receive channels.
Nominal impedance 50 ohms.
SWR < 1.5 for frequencies between 9 and 15 MHz.
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Bandwidth
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2 MHz at -3dB.
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Supply
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DC +15V and -15V at 0.65 A (20W)
The supply is connected on a 9-pin d-sub.
pin 9 = DC ground
pin 5 = +15V DC, 0.65A
pin 4 = -15V DC, 0.65A
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Computer interface
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A simple computer interface is used to select one of the
four crystals.
The computer interface is on the same 9 pin d-sub connector
as the supply voltage.
pin 1 = Select
pin 2 = Data
pin 3 = Status
pin 6 = Clock
pin 9 = Ground
Do not connect the d-sub connectors to the RX70 unless you are sure
the box is properly connected to the computer chassis and the power supply
zero.
The parallel port interface is an open drain, a 74HC03, and it may be
damaged by static electricity.
Repairing the RX70 is trivial, but if the computer parallel
port is damaged, repair is not easy.
Making sure that ground is connected before the cable to a computer
parallel port is connected is always a good idea.
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Sensitivity
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Noise floor in 500 Hz bandwidth -138 dBm (NF = 9 dB).
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Gain
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0 dB.
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Dynamic range
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1 dB compression point +18 dBm.
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Third-order
intermodulation
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Two signals at 0 dBm produce third order intermodulation
below -57 dBm (IP3 > +28 dBm).
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Weight
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1.4 kg.
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Size
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48 mm x 218 mm x 350 mm.
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The RX70 is inteded to be used together with the RX10700,
the RX2500 and a modified Delta 44 soundcard.
Read about the Delta 44 soundcard modifications here.
System performance data for WSE RX70 used with a
WSE RX10700. a WSE RX2500 and a modified Delta 44
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Sensitivity
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System noise floor in 500 Hz bandwidth with the Delta 44
in minimum gain mode -131 dBm (NF = 15.5 dB).
System noise floor in 500 Hz bandwidth with the Delta 44
in maximum gain mode -134 dBm (NF = 12.5 dB).
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In-band dynamic range
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Level for A/D saturation -14 dBm.
Noise floor relative to near saturating carrier at 5 kHz frequency
separation with Delta 44 in minimum gain mode -144 dBc/Hz.
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Out-of-band dynamic range
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Level of interference that causes 3 dB loss of S/N for a weak signal
with Delta 44 in minimum gain mode.
Frequency Level
separation (dBHz)
50 162
70 166
100 171
200 173
400 >175
Carrier above noise floor in 1 Hz bandwidth.
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The WSE RX70 is designed by SM5BSZ, Leif. A detailed description is
available at:
details of the RX70.
Some general information about the WSE converters is available here:
the WSE converters.
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