Re: VLF: TX on 6.47 and 8.97

["mal hamilton" <g3kevmal@talktalk.net>]

Markus

There was another carrier visible at my qth. This carrier was visible after you switched off but it also went qrt around 1340, the frequency was 8970 kcs but not calibrated at my end so could be a little out. Maybe this carrier was seen by F1AFJ if it is not your transmission.

I wonder if anyone else in the UK detected any signals

Gl with your experiments.

de mal/g3kev

 

----- Original Message -----

From: Markus Vester

To: rsgb_lf_group@blacksheep.org

Cc: Paul

Sent: Saturday, November 13, 2010 10:04 PM

Subject: Re: VLF: TX on 6.47 and 8.97

Dear LF, Paul,

 

here's a short summary of today's VLF kite transmission. I'm sorry for the late notice, but the experiment had not been planned ahead, and I wasn't sure if I could get on at all. Also, the kite I am using (a 0.8 m^2 delta toy bought for 4.99 Euro) is a bit small for this sort of activity, and really requires a good and steady wind.  

 

The QTH was actually at 49.3874 N 11.1692 E, a few 100 meters from the former location reported earlier. The GPS-controlled carriers were on air

 11:15 - 12:15  6470.000 Hz ~ 50 uW, and

 12:30 - 13:10  8970.002 Hz ~ 200 uW (EMRP).

 

Getting on 6470 was easier than expected. I simply used the same "seven-bucket" coil, which resonates my 240 pF home antenna to 8.97 kHz. Connected to the kite wire, the resonance was close enough to 6.5 kHz to be tuned by the ferrite plate variometer. Then the drive for the audio amp was increased until the onset of corona sizzling at 0.25 A. At that point, the amp drew 10 A DC from the car battery and probably delivered around 50 W. After connecting mobile internet and staring at Stefan's grabber, I was positively surprised to find a faint trace there!

 

For the frequency change, I removed the two bottom coil buckets, which brought the resonance to ~ 8.5 kHz. Then I had to carefully pull the remaining 5 buckets apart, inserting bits of plastic foam material as spacers. Going through a few iterations took about 10 minutes, and I got to "full power" (380 mA, 100W) at 12:30. Unfortunately, the wind had started to calm by then, and there were several dips during this transmission. Finally at 13:10, the kite landed gently in the grass, and I decided to close down and pack up early.

 

Traces from both transmissions were visible on DK7FC's 4.5 mHz "600" windows, and the second one also produced a nice dash on the 0.45 mHz window. It is likely that these signals would be useful for a kite-to-kite QSO on either frequency, using 10 minute dashes.

 

The screenshot from F1AFJ has an interesting dash before 13:00. The indicated frequency seems a bit high (8970.020 instead of 8970.002), which could perhaps be due to a small samplerate calibration error. I am also not sure about the time scale  - judging by the width of the noise blobs, the setting could have been 11 mHz and 10 seconds per pixel. It would be nice if Jean-Pierre could confirm the frequency calibration and scroll settings.

 

I also carefully inspected the OE3GHB grabber, which runs at 1.4 mHz resolution and seems to be very sensitive. It showed an unusually dark period of very low noise between 8 and 11 UT today. But no luck for my transmission there yet.

 

Well, in addition to the technical aspects, being outdoors in the warm wind was again a rewarding and enjoyable experience.

 

Best 73, and thanks again for the interest.

 

Markus (DF6NM)

From: Markus Vester

Sent: Saturday, November 13, 2010 2:19 PM

To: rsgb_lf_group@blacksheep.org

Subject: Re: VLF: TX on 6.47 and 8.97 - QRT

Sorry folks, I had to shut down at 13:10 due to lack of wind. Many thanks for looking!

 

Best 73,

Markus (DF6NM)

 

From: Markus Vester

Sent: Saturday, November 13, 2010 2:08 PM

To: rsgb_lf_group@blacksheep.org

Subject: Re: VLF: TX on 6.47 and 8.97

Hi Stefan, thanks for the observation! I am approximately at 49.3851 N 11.1727 E. After a bit of fiddling with the coil, the carrier is on 8970.002 since about 12:25. I will try to stay on till 14:00, but there are a few lows as the wind has calmed down a bit.

 

73, Markus

 

From: Stefan Schäfer

Sent: Saturday, November 13, 2010 1:50 PM

To: rsgb_lf_group@blacksheep.org

Subject: Re: VLF: TX on 6.47 and 8.97

There is a trace now coming up slightly above 8970 Hz in the DFCW-600 window :-)

Markus, what is your exact locator? http://no.nonsense.ee/qthmap/  Let us see where you are currently :-)

73, Stefan

Am 13.11.2010 13:16, schrieb Stefan Schäfer:

Wow! Hi Markus,

Good luck!! Yes, the wind is very strong indeed. For my kites it is almost to strong...
With your kite you should easily be visible in the 6000er window on 8970.

OOOH! I just looked on my 2nd VLF grabber http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html and saw your trace in DFCW-600!
Congratulations Markus!!!! This is the second amateur radio station at all who reaches the far field within the 46km band :-) i estimate 8 dB S/N maybe 10. Great!!!

So DFCW-600 on 8970 should be no problem later :-))

Who else of the group is monitoring? It would strongly interest how Markus is received at other locations :-)

Best 73 and wish FUN!!

Stefan/DK7FC

Am 13.11.2010 12:54, schrieb Markus Vester:

Nice wind here in Nuernberg, and I'm back on the /p QTH with my small kite (100m wire, kite currently about 60m up). Since 11:15 I am sending a carrier on 6470.00, trying to generate a small peak on DK7FC's second grabber. Max current into the thin wire is about 0.25 A. After one hour at 12:15, I intend to switch to 8970.002 Hz, where I can radiate about 0.2 mW at 0.4 A.

 

Best 73,

 

Markus (DF6NM)