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Re: VLF: 8.27

To: [email protected]
Subject: Re: VLF: 8.27
From: DK7FC <[email protected]>
Date: Fri, 13 May 2016 19:08:17 +0200
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Hi Roland,

Am 13.05.2016 18:48, schrieb Roland Bruestle:
Hello Stefan,
ok, it should be 8270kHz.
I assume you mean 8270 Hz.
I have now decreased the turns on the primary winding.
As long as the transformer stays cool, you can do this. But for higher power levels it may be better to add more turns on the secondary winding. You need to watch it.
The antenna current is now 350mA, input power to the PA is 150W.
Cooler temperature remains still 37°C.
The transmission is finished since 15:00 UTC. I hope you can give me some report.
Are you using a Mini Whip for receiving? I will try to receive you on you next transmissions.
As i wrote, i am using a loop into E-W direction.

Oh, i just wanted to ask if you know you signal accuracy but now i saw your signal on the DF6NM VLF grabber. It has been on the air for about one day and it looks absolutely stable. I also see a dash on the right frequency in my 47 uHz window but it disappeared during the time of low QRN. I can even see a faint trace in the 424 uHz window. I guess Paul will have even better traces.

Now what are your plans, what would you like to do there? Carriers, DFCW, EbNaut?
Ah and BTW, now your antenna C has rised since you improved the antenna. So you must have reduced the L. Do you have enough L available to go to 6470 Hz? It would be interesting to see if the daytime propagation on our short path is better there.
I will soon move to 5170 Hz, so the frequency would be clean for you :-)

73, Stefan

PS: My peak hold graph was set wrong in the 47 uHz window. It is now updated and shows the highest peak of the last 3 days.


Am 13.05.2016 um 18:21 schrieb DK7FC:
Hello Roland,

I have the EW loop connected on the tree. Don't hesitate to run a carrier during the morning hours, 4...10 UTC is a good time as you can see. With some luck i will see you in the 424 uHz window. That would be remarkable.

73, GL, Stefan

Am 13.05.2016 09:36, schrieb Roland Bruestle:
Hello Markus, Stefan, Paul,
I'm back at 8170kHz and using now a class D Amplifier. You can see me at Markus Grabber.
Amplifier :
max. power on 2 Ohm: 500W
mac. power on 4 Ohm: 250W
Power supply range. 20..48V
Switching frequency: 400kHz
IC: Texas DTA8950
IC is fan cooled
Price,  mono mode: Ebay, 50 €

My actual values:
Power supply: 30V, 3A = 90W
PA output about 80W
Antenna current: 250mA
Temperature of cooler: 37°C
Fan mostly switched off

For more power I have to increase the voltage of power supply or to lower the primary turns of the transformer.
300Ws should be not a problem.

For receiving I wont to use a min whip. I hope that the noise is not to high.

Roland DL3NDR

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