Markus, VLF,
Oh! Yes indeed. I can also see my signal on the "DFCW-600" window of
OK2BVG: http://www.ok2bvg.cz/vlfgrabber/ :-) Unfortunately the OE3GHB
grabber is down...
Currently i am running 350W constant. I am limited to 830 mA and run
about 800 mA now. If i increase the power/voltage, then i can see up to
8 cm long sparks flashing over on the cola-cap ;-) So that is one of
the next tasks here, building a better cap.
Also i lost one of the F3.15A fuses that protects a half of the H
bridge. Luckily the FETs were still working after replacing the fuse. I
highly expect the problem is a longer fiber optic cable that was in use
to that time, so that i can generate and apply the frequency coming
from the notebook in the shack, about 10m distant. The higher losses in
the longer optic cable deformed the pulses and so the 2/1 divider
(CD4013) got a bad signal and did some undefined things...
I am now working for a better drive of the LED here (7667...) and then
switch to the PC again (currently using the DDS again since it has a
12V output that can drive the LED very well. Here, no glitches occurr.
Then i will have something to eat and run the system for some hours i
hope. I will then announce the exact start and stop times so that Paul
Nicholson can try to integrate over the entire TX time...
73, Stefan/DK7FC
Am 26.11.2011 16:33, schrieb Markus Vester:
Stefan,
around 15:00, your sig on 8970.008
was visible in Nuernberg, peaking ~ 20 dB SNR in 0.48 mHz.
Viel Glück,
Markus (DF6NM)
Sent: Saturday, November 26, 2011 3:57 PM
Subject: Re: VLF: 8970 Hz transmissions, soon again here
VLF,
I'm now running 350W into the system and get about 0.8 A antenna
current. Strong audible partial discharges occurr on a parallel fixed
plate capacitor, spaced by 3 cola bottles (0.33l ;-) ). At 550 mH i
have
25 kV rms on the antenna and coil which seems to be no problem at all.
The frequency is still a bit unstable since i took the DDS VFO which is
more comfortable to find the resonance. I will now try to slightly QRO
and then apply a fiber optic cable carrying the GPS locked frequency
coming from the PC/SpecLab, hopefully without to many phase glitches.
Currently i may have an offset of some 20...30 mHz and a slight drift
but it is a first successfully test :-)
73, Stefan/DK7FC
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