вторая:
Hi all,
I've added a small air gap to my transformer and increased the number of
turns on the transformer (which meanwhile just acts as a loading coil).
Now there are 7 layers and about 1400 turns. The new resonance is 2.87
kHz. I put 6.8 nF (and 47kOhm in parallel) in series to the antenna to
move the resonance to 2.97 kHz. It is better to 'sit' on top of the
resonance because there is a risk of a flash over when it starts to rain
(the C of the wet antenna would be higher, so i come closer to the
resonance and so the voltage would rise).
At 1.4 kV i'm now getting about 14 mA antenna current and 25 nW ERP!
The signal is now well visible in my 3.8 mHz window at
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.htmlAt 5 UTC i'm running a first EbNaut message in 10s symbols, just local,
just for the fun.
The next step would be to wind further 1600 turns on the transformer to
reach its final voltage limit of 3 kV (rms) and 100 nW ERP.
A photo of the transformer
https://dl.dropboxusercontent.com/u/19882028/VLF/ULF%20loading%20coil%206.1H.jpg73, Stefan
странно, как показала практика на 136 кгц - многослойные катушки на передачу- не эффективны. только однослойные и большого диаметра.
с максимальной добротностью, по возможности.
понятно, что он там не от хорошей жизни использует сердечники и многослойные катушки, но всё же...
