WSE (Weak Signal Equipment) A joint effort by SM5BSZ Leif and SM7UFW Niklas.
(Dec 17 2011)
The WSE RX144 is a converter that converts two radio frequency signals at 144 MHz to 70 MHz.

The WSE RX144 is designed for use together with the WSE RX70, the WSE RX10700 and the WSE RX2500 to form a high performance two channel receiver for 144 MHz. The output bandwidth is 2 times 93 kHz. The output is intended to be digitized by a high performance soundcard sampling four channels at 96 kHz.

The WSE RX144 contains four crystals and allows the 93 kHz wide frequency band seen by the computer to be centered anywhere between 143.975 and 145.950 MHz in 25 kHz steps.

The RX144 provides very high dynamic range but it is not intended to be connected directly to an antenna. Preamplifiers with adequate gain and dynamic range should be used.

The WSE RX144 was sold in the years 2002 to 2010 in a quantity of about 50 units for a price of 3120 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 RX144 technical data

Input Two BNC connectors for two receive channels.
Nominal input impedance 50 ohms.
SWR < 3 for frequencies between 143.5 and 146.5 MHz.
Maximum input RF power +30 dBm.
Output Two BNC connectors for two receive channels. Nominal impedance 50 ohms.
SWR < 3.5 for frequencies between 69.5 and 71 MHz. (The output impedance is 25 ohms but linearity is optimum for a 50 ohm load)
Bandwidth 4 MHz at -3dB.
Supply DC +15V and -15V at 0.7 A (20W) The supply is connected on a 9-pin d-sub.
pin 9 = DC ground
pin 5 = +15V DC, 0.7A
pin 4 = -15V DC, 0.7A
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 RX144 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 RX144 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 -139 dBm (NF = 8 dB).
Gain 8 dB.
Dynamic range 1 dB compression point +10 dBm.
Third-order intermodulation Two signals at 0 dBm produce third order intermodulation below -40 dBm (IP3 > +20 dBm).
Weight 1.4 kg.
Size 48 mm   x   218 mm   x   350 mm.

The RX144 is inteded to be used together with the RX70, the RX10700, the RX2500 and a modified Delta 44 soundcard. Read about the Delta 44 soundcard modifications here.

System performance data for WSE RX144 used with a WSE RX70, 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 -137 dBm (NF = 10 dB).
System noise floor in 500 Hz bandwidth with the Delta 44 in maximum gain mode -140 dBm (NF = 7 dB).
In-band dynamic range Level for A/D saturation -22 dBm.
Noise floor relative to near saturating carrier at 5 kHz frequency separation with Delta 44 in minimum gain mode -143 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)
       100             >165 Carrier above noise floor in 1 Hz bandwidth.

The WSE RX144 is designed by SM5BSZ, Leif. A detailed description is available here: details of the RX144

Some general information about the WSE converters is available here:
the WSE converters