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Last update: 01. 01. 2010



 The receiver 134 – 141 MHz in execution Professional is placed in a ”luxury” box made by BOPLA and it has moreover another electronic circuit for recognition of presence of the signal WEFAX 2400 Hz, which collaborates with the system of automatic search of current passage of the satellite NOAA and stopping of the mode SCAN at the current frequency in the band 134.00 MHz – 141.00 MHz. 



Front panel contains control push-buttons for selection of working frequencies, working mode of the receiver and a switch for selection of antenna, from which the received signal will be processed.



Rear panel of the box contains two antenna connectors for independent connection of signal from converter LNC1700 and signals from antenna Turnstile for polar satellites. Rear panel also contains 2 connectors CINCH for connection of speaker and for cable from the computer sound card. The fifth connector serves for connection of power supply + 12 V. The set comprises also power supply +12 volt / 500 mA. The receiver in execution PROFESSIONAL is ready for reliable operation in continuous mode on professional worksite.  


  • Pre-amplifier GaAs FET 1,7 GHz +25 metre coax. cable + connectors

  • The assembled and tuned Converter: 1691.00 - 1694.50 MHz / 137.50 - 141.00 MHz or 1691.00 - 1694.50 MHz / 134.00 - 137.50 MHz

  • The assembled and tuned receiver 134 - 141 MHz / 30 kHz / step 10 kHz with LCD display with USB connect

                         ... is available at a price of 442 EUR 


  • The assembled and tuned receiver 134 - 141 MHz / 30 kHz / step 10 kHz with LCD display 

...  (separately - only receiver) is available at a price of 241 EUR 


Receiver technical data

Frequency Range  134 (7) - 141 MHz (infinitely adjustable, step by step 10 kHz)
 Frequency Synthesizer Step:  10,0 kHz
 Input Sensitivity:  0,25uV (rms-type) for 12dB SINAD
 Intermediate Frequency:  10,7 MHz and 455 kHz
 Tone decoder/PLL SE567:  2400 Hz
 Pass band of the 2-st.IF filter:  30 kHz/ - 3 dB
 Power:  DC 9 V (max.12 V)
 Current output:  70 - 90 mA, according to the loudness level setting
 Power Connector:  3 mm (+ pole is inside of the jack pin, - pole is on its surface!!!)
 WXtoIMG Scanning:  Yes / 10 -channel, controlled by the uP [ RS232/1200bit/sec. ]
 Automatic Scanning:  Yes - 2400 Hz stop point - Squelch function controlled by the uP
 Noise Gate ( SQUELCH ):  Yes 
 Antenna Connector:   "2x SO239" type or "2x BNC" type
 Display:  LCD 1 x 16 alpha - numerical  symbols
 Connection for Loud speaker:  (or Headphones) external 8-25 Ohms, CINCH connectors
 Connection for PC:  PIN connectorsor cable from the computer sound card & USB
 Receiver Size:  225x200x70 mm


The RX137141MHz receiver (old model) has already been produced since 1998 and I have been gradually implementing various improvements of its technical parameters. The most recent modification of the service properties of the receiver consists in a possibility to connect it to a PC via the USB interface.



This modification was initiated by the interest of the WXtoIMG decoding program http://www.wxtoimg.com/hardware/  users. The WXtoIMG program has outstanding properties for decoding of the APT signals and it enables a completely automated operation and optionally also an automatic sending of the decoded image to the chosen web page. The WXtoIMG program sends a special code into the receiver shortly before the rise of the satellite to the horizon, which will trigger the setting of the receiver to one of the following 10 frequencies ( 137.20 .. 137.10 .. 137.40 .. 137.50 .. 137.62 .. 137.9125 .. 137.30 .. 137.70 .. 137.80 .. 137.85 MHz ). The process is continuously repeated before each flyover of the satellite in the cycle, which is updated from the database of the current Keplerian elements. The selection of the frequency for the given satellite is substantially more reliable at present than it was in older models of this receiver, with the use of SQL SCAN or PLL 2400 Hz SCAN with the LM567circuit. The impact of interfering signals on the receiver’s input that afterwards caused a process of undesired repeated scanning never occurs now. 

At present I have started the production of a new model of the RX134141MHz receiver with an extended range that was inspired by the needs of users of the converter 1700MHz made in Italy, the output frequencies of which are 134.00 a 137.50 MHz. The new model of the receiver embodies all good properties, which were confirmed during a six-year-long practical use by numerous users in many countries.



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