WSE (Weak Signal Equipment) A joint effort by SM5BSZ Leif and SM7UFW Niklas.
(Dec 17 2011)
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

Input 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.
Output Two BNC connectors for two receive channels. Nominal impedance 50 ohms.
SWR < 1.5 for frequencies between 9 and 15 MHz.
Bandwidth 2 MHz at -3dB.
Supply 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
Computer interface 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.
Sensitivity Noise floor in 500 Hz bandwidth -138 dBm (NF = 9 dB).
Gain 0 dB.
Dynamic range 1 dB compression point +18 dBm.
Third-order intermodulation Two signals at 0 dBm produce third order intermodulation below -57 dBm (IP3 > +28 dBm).
Weight 1.4 kg.
Size 48 mm   x   218 mm   x   350 mm.

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

Sensitivity 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).
In-band dynamic range 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.
Out-of-band dynamic range 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.

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.