SARS YA10MB Project
Posted: Fri Jan 08, 2016 7:53 am
Over the last 3 months, I have been building up "Yet Another 10M Beacon" on behalf of the Southside Amateur Radio Society (based in the Logan area of SE Qld) to fill the lack of an official 10M beacon in the lower physical segment of Queensland. The beacon is currently set to 28.220MHz and will be co-sited on Mt Cotton with the SARS 2M voice repeater very shortly. It is currently undergoing burn-in into dummy load at my home QTH but should be on an external antenna early next week (11-13 January 2016). Preliminary reports after 13/1/2016 would be appreciated.
While it is not currently GPS-locked, it could be as the internal frequency reference VCTCXO is is 10.0000MHz and an external 10MHz signal could be utilised. Typical frequency accuracy is within about 2Hz at this stage.
The new beacon utilises a PICAXE controller to program the frequency synthesizer plus the expected normal housekeeping functions. It also provides dynamic RF power level control such that the beacon produces 4 discrete RF output powers. The control cycle is as follows and is based on around 15 seconds per function:
Morse “1” followed by carrier for 14 seconds at the 1 watt level
Morse “2” followed by carrier for 14 seconds at the 2 watt level
Morse “5” followed by carrier for 14 seconds at the 5 watt level
Morse “H” followed by carrier for 14 seconds at the 10 watt level, where the H stands for the highest power level.
It then does a full CW ID at about 10-12WPM, including callsign/B and maidenhead grid square. There are also optional morse characters LV and HV tagged on which indicate that the supply voltage is below 12.0V or above 14.4V respectively.
The beacon will automatically correct for ageing or thermal detuning effects as it undertakes a power-setting sequence at each power setting change (ie the 1, 2, 5 and 10 watt levels) and the transmitter is capable of producing about 15 watts at true full power.
The physical unit utilises just a new exciter PCB coupled with a ‘frequency-shifted’ Philips FM828/25E PA board and is housed in a stripped-out FM828 chassis.
73
Doug VK4ADC
While it is not currently GPS-locked, it could be as the internal frequency reference VCTCXO is is 10.0000MHz and an external 10MHz signal could be utilised. Typical frequency accuracy is within about 2Hz at this stage.
The new beacon utilises a PICAXE controller to program the frequency synthesizer plus the expected normal housekeeping functions. It also provides dynamic RF power level control such that the beacon produces 4 discrete RF output powers. The control cycle is as follows and is based on around 15 seconds per function:
Morse “1” followed by carrier for 14 seconds at the 1 watt level
Morse “2” followed by carrier for 14 seconds at the 2 watt level
Morse “5” followed by carrier for 14 seconds at the 5 watt level
Morse “H” followed by carrier for 14 seconds at the 10 watt level, where the H stands for the highest power level.
It then does a full CW ID at about 10-12WPM, including callsign/B and maidenhead grid square. There are also optional morse characters LV and HV tagged on which indicate that the supply voltage is below 12.0V or above 14.4V respectively.
The beacon will automatically correct for ageing or thermal detuning effects as it undertakes a power-setting sequence at each power setting change (ie the 1, 2, 5 and 10 watt levels) and the transmitter is capable of producing about 15 watts at true full power.
The physical unit utilises just a new exciter PCB coupled with a ‘frequency-shifted’ Philips FM828/25E PA board and is housed in a stripped-out FM828 chassis.
73
Doug VK4ADC