SAQ Test Transmission on 2024-12-20

[Roman]

The test transmission of SAQ could be received in JN48MM starting approx. 13:05 UTC with about 12…15 dB SNR. Unfortunately, there is now a very strong signal at ~ 16 kHz and harmonics every 50 Hz which makes reception difficult. Most likely a just recently installed solar inverter :'(
Interesting to see on the waterfall how the frequency increases by 10…20 Hz after key down and returns to the target value after key up. Also, the “unwanted” carrier can be seen in the spectrum. Is there an estimation of how much antenna current is flowing or how much power is still being transmitted during “silence”?

Rx1: PC-Soundcard and Spectran V2 (I2PHD and IK2CZL)
Rx2: Elecraft K3 with home made upconverter (https://dl3tu.wordpress.com/2022/12/18/home-made-vlf-converter/)
Ant: Mini-Whip at the roof top

73, Roman – DL3TU

Topic

[AlexanderSAQ]

Dear Roman,
Thanks for your feedback on our test with SAQ on Dec 20th 2024.

During the test transmission, we did a lot of tuning to try different methods and approaches to get a good and stable signal. Only for shorter periods of time, we ran with a steady signal, the rest of the time, we tuned, something you also heard. We also started up the “V” wheel, which is an original mechanical device from the 1920’s, which can produce the morse character “V” in an endless row. Initially the speed was very high but we were able to set it to approx. 20 wpm after some time.
Our morse code operator was also keying a short test message. We feel that we managed to get a strong and stable signal out from our antenna and everything looks promising for the Christmas transmission on Dec 24th.

The leakage in the magnetic amplifier can be as high as 10%, but we have not been able to measure it yet, it is a very difficult environment there with voltages up to 10 kV, depending on where you want to measure. We will work on getting these measurements done any time soon.
The output power is about 80kW to the antenna, we don’t want to magnetize the Alternator any harder due to its age.
At full power, 200kW, the antenna current is close to 100A in each vertical down-lead from each tower, however, for the last decades it has been set to about 35A.
The Antenna efficiency was originally 14% but nowadays it is more likely close to 10%, due to its age, meaning that we manage to get some 8kW into the ether at key-down.

Fredrik / Alexander association

[Roman]

Dear Fredrik,

thanks for your reply and the many details about the alternator and the antenna system. It is wise not to challenge a 100-year-old machine too much anymore, although 80kW is still a lot of power! Considering antenna efficiency and leakage of the magentic amplifier, I would estimate there are still several hundred watts being transmitted between the dashs and dots. Not enough to be heard in my noisy environment but enough to be visible in the waterfall.
I’m looking forward to watching the live stream and listening to the transmission in a couple hours.

Best 73 and mx,
Roman

[John]

All the answers to your questions are here:

https://archive.org/details/TheAlexandersonSystem

[Roman]

Many thanks, John! Amazing stuff to read during the next couple days 🙂

73, Roman

[Author]

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