Thursday, March 14, 2024

Low band VHF tests by Tony Mann in Western Australia - 2023

 In a previous post, I looked at the Low Interference Potential Devices (LIPD) Class Licence in Australia and how it allowed individuals to transmit with very low power in parts of the low-band VHF spectrum.

Tony Mann is a radio experimenter in Perth, Western Australia and has over the last 12-months been operating four beacons in the low-VHF bands with each one running 100 milliwatts.

The frequencies were 30.8761 MHz , 36.6073 MHz, 39.1467 MHz and 40.6864 MHz.

In 2023, several stations heard the beacons and there are shown on the map above.

Short wave listener Hugh Cocks (HC02) is in the south of Portugal. Phil, EI9KP is located in the west of Ireland. Paul, G7PUV is located in the SE of England. All three are in the region of 15,000 kms.

Otto, VK4OTZ in Queensland, Australia is about 3,700kms to the east which is pretty much ideal for one F2 layer hop.

Tony informs me that he initially made a single frequency “beacon” on 36.860 MHz for the southern hemisphere F2 season in March-May 2023. It was simple crystal oscillator modulated by a PIN diode.

By July 2023, he had a second beacon on 30.876 MHz which was still heard in Sydney via F2 up until September 2023. By that time, Hugh Cocks in Portugal was interested in trying, so he ran 30 MHz after late Sept 2023, quickly added 36 MHz, then 39 MHz by 10 Oct and finally by 29 Oct had a 4th, 40 MHz beacon running.  

The 36.860 MHz frequency was changed to 36.607 to avoid DX radar interference in Europe. The 40 MHz beacon was never received as by mid-Nov 2023 conditions had deteriorated. 

Tony's antenna is shown below...

Tony uses two vertical dipoles: On the left is a single dipole for 30.9 MHz and on the right is a folded dipole for 36-41 MHz (which works adequately on 30.9 MHz).

The beacon signal is alternately switched on for 0.5 seconds, then off for 1.5 seconds. The cycle repeats every two seconds. There is a  0.5 second gap where no power is going out.

The screen grab above from Hugh, HC02 in Portugal shows what the 39.1467 MHz signal looked like on the 11th of March 2024.

Videos... This clip from Paul, G7PUV shows reception of the 30.876 MHz signal...  

The video clip below shows reception of the 36.860 MHz signal by VK4ATZ...

Current Status - March 2024: Tony is currently carrying out propagation tests as we're close to the equinox.

Tony writes... "I am ready to resume the 07-11 UTC tests for Europe in March 2024 and I anticipate adding 00-04 UTC for the autumn F2 season in Australia."

It would be interesting to see more reports of people hearing Tony Mann's beacons. Perth to North America? Perth to South America?

If you hear anything then you can leave a comment here.

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