SARS YA10MB Project

[VK4ADC]

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

[VK4TI]

hearing it well enough 220 cwusb

[VK4ADC]

Currently running with CW ident as "VK4ADC/B QG62LG" & will be until it is moved from here. Best aural tone with receiver set to 28.21940 ie 600Hz.

Actual frequency as measured against a GPSDO reference is 28220.002 MHz ie 2Hz high, but that can be adjusted out anytime.

It is temporarily on a 1/4 wave whip about 2.4m above ground during the burn-in phase & when not on dummy load.

The beacon should be 24x7 sometime during the next few days - once I have my FD batteries back in the shack and back on the solar charger - after the Summer VHF/UHF FD tomorrow & Sunday. Until then it is only available when I have the shack bench power switched on.

[VK4ADC]

The beacon is now powered by solar-power charged batteries so is up 24x7 - except for any small outages for final "tweaks". I have had a few signal reports emailed in from southern states so it is obviously being heard outside the local SEQ area.

I have added a web page about the beacon on my website at http://www.vk4adc.com/web/index.php/hf- ... n/191-28bp

[VK4ADC]

Email dated 15 January 2016:

"Doug,

This morning at 0900 UT I could cpy ur new beacon on 28220 kHz for the first time, very weak with S2. 5B4CY was not audible at that time.

Due to the low signal I did not wait for identifying the pwr level at that moment but the signal here will improve providing better reception windows when you have moved the beacon.

I was really astonished that even the present preliminary qth did provide a path to Europe.

I'm listening with a 3 ele beam and the TS-590SG. My location is nr Koblenz, in JO30WE.

Pse inform me when you put the beacon to the final qth.

Tnx fer starting it with so much design work es 73!

Andre DL8WX

"

Visit Andre's web site HF beacons page at http://www.dl8wx.de/baken_kw.htm

[VK4ADC]

At a meeting of SARS on 20 January 2016, it was agreed that the frequency suggested by Andre DL8WX as being clear in Europe be implemented.
The frequency was changed from 28.220 to 28.211500 on 21st January 2016 and put back on air to antenna at 0000Z.

It will still have a callsign change from VK4ADC/B when it is moved to Mt Cotton.

Reports would be appreciated, particularly noting reception at the lower power levels.

[VK4ADC]

See below for more details about the update

[VK4ADC]

28MHz SARS Beacon Update
24 July 2016

The ID cycle for the amplitude keying and power sequence has been altered to the following:
0 to 6 seconds: Fast CW identification, short callsign only, followed by brief pause at highest achievable RF power level (>5 watts)
7 seconds: Carrier only at power level 9 (5 watts, reference RF level i.e. 0dB) for one second
8 seconds: Carrier only at power level 8 (2 watts, -4dB) for one second
9 seconds: Carrier only at power level 7 (1 watt, -7dB) for one second
10 seconds: Carrier only at power level 6 (0.75 watts, -9dB) for one second
11 seconds: Carrier only at power level 5 (0.5 watts, -10dB) for one second
12 seconds: Carrier only at power level 4 (0.25 watts, -13dB) for one second
13 seconds: Carrier only at power level 3 (0.1 watts, -20dB) for one second
14 seconds: Carrier only at power level 2 (0.05 watts, -23dB) for one second
15 seconds: Carrier only at power level 1 (lowest RF power level, about 0.01 watts, -30dB)
16 to 19 seconds: Sequence pause - carrier only at power level 1 – note that the carrier is not completely switched off. If you can hear this level then propagation between the beacon and you is extremely good!
This 20 second cycle then repeats with the full CW identification every 6th time.

Notes:
1. All RF power levels have been calibrated into a true 50 ohm load. Variations in antenna impedance may cause the final power level to change BUT the relative power ratios will remain about the same.

2. The above power ranging allows the received signal to vary about 30-40dB e.g. from S9 (at the 5 watt power level) down to below S0 (at about 10mW) on a typically calibrated S-Meter.

3. The CW identification is expanded approximately every 120 seconds so that the grid locator is transmitted along with any low supply voltage (LV) or high supply voltage (HV) status alarm.

4. The beacon undertakes an RF output recalibration approximately every 30 minutes and this becomes evident in that the received signal level is seen to cycle upward (rather than downward as happens during the normal ID cycle). The RF output recalibration also occurs immediately after DC power is applied to the beacon and prior to the normal 20 second ID sequence commencing.

This follows a change to a new PA section utilising a RD16HHF1 linear-mode HF FET which makes RF power stepping a lot easier.. ( http://www.mitsubishielectric.co.jp/sem ... 16hhf1.pdf )

Frequency is 28.21150 and callsign is still VK4ADC/B.

Reports would be appreciated....

73 Doug VK4ADC

Project page : http://www.vk4adc.com/web/index.php/hf- ... on/43-28bp