Re: VLF: New coil for 8270 Hz

[Markus Vester <markusvester@aol.com>]

Nice piece of work  Stefan! I liked the measurement notes on the coil base ;-)

I'm glad to read that you are close to returning to Dreamer's band. It will hopefully spawn new activity, and motivate others to transmit, receive, decode, or bring their grabbers back online.

Good luck for the nail-biting high voltage test!

All the best,
Markus (DF6NM)



-----Ursprüngliche Mitteilung-----
Von: DK7FC <selberdenken@posteo.de>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Mi, 28 Dez 2016 6:11 pm
Betreff: VLF: New coil for 8270 Hz

Hi VLF,

Today was (is) a good day. For the first time i tested the new VLF coil
on the antenna. The coil is built for 8270 Hz. The DC resistance is just
230 Ohm! It is intended to run 700 mA. A 3 layer coil, each layer has 30
turns, overlapping the last layer with 20 turns. So far it has 70
layers. And the diameter is 0.25 m. So thats super compact and robust.
About 50 hours of winding though!
In a first test i measured 230 mA RF current and the power supply showed
0.94 A and 24.5 V. So that's just 23W including PA losses. Not bad at all.
However the resonance frequency is 8.607 kHz, and that's why the coil is
back in the shack now, waiting for another 3 layers. But soon i will be
there...

https://dl.dropboxusercontent.com/u/19882028/VLF/20161228_151854.jpg

73, Stefan