30m QRSS Beacon PDF Print E-mail
Written by Hans Summers   
Wednesday, 06 May 2009 05:22
A borderline insane 30m QRSS beacon project, completely independent of computer control and containing NO microprocessors! The beacon contains an 8K EEPROM (28C64 chip) of which only 1K is used. It is programmed by hand from front panel switches. The controller is capable of the following modes:

o 12 WPM ordinary CW
o QRSS3 (CW with 3 second dot length)
o QRSS10 (CW with 10 second dot length)
o DFCW3 (dual frequency CW with 3 second dot length)
o DFCW10 (dual frequency CW with 10 second dot length)
o A type of slow-hellschreiber

These very narrow bandwidth modes are decoded using a Fast Fourier Transform (FFT) program running on a PC. For more details of these modes visit ON7YD's Extreme narrow bandwidth techniques page.

This project was/is a long series of modifications, operation periods, reports, and endless expenditure of frustration, patience and sometimes jubilation. Eventually I received reception reports from all around Western and Northern Europe. Since I have a large quantity of material on this topic I have divided the page into a series of sub-pages, which are presented below in chronological order.

30m Transmitter:

At the heart ot the beacon is the 30m transmitter itself. It uses a 74HC240 octal inverter IC as a power amplifier in push pull configuration. One inverter of the 74HC240 is a VCO using a 10.125MHz crystal... Read more...
Beacon Controller:

The QRSS controller uses an Electrically Eraseable Programmable Read Only Memory (EEPROM) to store the sequence of transmitter states to make up the QRSS message. It is unique amongst QRSS beacon controllers in so far as it does not require a PC to operate or program, and it contains no microcontroller! Read more...
26-Mar-04 to 04-Apr-04:

Initial transmissions during Christmas 2003 had failed to produce even a single report. In March I tried again. After construction of a 30m receiver for monitoring and calibration, I received my first reports. There followed an intense period of modifications, improvements, and more tests with receiving stations in Sweden, Belgium, The Netherlands, Germany, Austria and the UK. The modifications centred around improved frequency stability, shift linearity, and multi-message capability. Read more...
25-Aug-04 to 27-Oct-04:

Another round of beacon experiments later in 2004 produced a whole new batch of reception reports. An important modification during this period was the addition of a tiny crystal heater supplied by DB6NT, which regulated the crystal temperature at 40.8C. During this period the beacon transmitted using an indoor antenna. Read more...

 


Last Updated on Wednesday, 06 May 2009 05:42
 
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