I used chokes instead of trafos as I could not get the right
trafo. The frequency response is 0 - 13. 000 Hz
with 2 X 82mH chokes in series and a 100mH bypass.
A portable TV provided two 124 cm whips, and they were
fitted with a BNC plug, by far the best solution. See diagram
on how to convert.
Earthing was a wired rod of aluminium
stuck into the ground
and connected into the RX via
a mini plug. I earthed the - end
of the circuit board too. For
field use I have an old tripod
which was perfect for the job,
also using a car cell phone
holder to hold the RX in position.
The Sony TCD-D8
Dat-recorder kindly supplied
by
Eringa, Groningen, has now
been tested and is perfect for
this kind of work. So this
is now the recording medium in tandem with the Marantz
CP 130.
We have tested the MZ R35 (
Mini-disk) and found
it unsuitable for this type
of work.
In the first version the antenna
is coupled via a phono plug
this has since been changed
to a BNC plug and socket.
So far there are no extra filters...yet,
so what you see is what
you get, see ELF
page. I found that away from buildings it worked well and
gave a good idea of what is
possible.
Good hunting..!!
Here's a few links if you missed them on the pages and one or two more:
Spectrogram program GRAM.EXE
INSPIRE
PROJECT (Basic
VLF Signals etc)
NOAA
Indices site
THE
CONET PROJECT ( you
must see this site)
+ CD recordings
Natural
Radio site
Updated 20-10-1999