Hi all,
Despite mostly overcast wx i spend 3 hours into the tree today. Now the
first of 3 accus is on the board, still not used. Also, the (mono-)
MF-RX is up and a shielded USB-soundcard is connected to the Raspi.
Further i have completed the installation of the first loop, beaming
about 120/300 deg. It is a single turn, circular(ish) loop with a
diameter of about 5m. The feed point (the highest point of the loop) at
about 15m above ground.
Measurements with a modified MFJ259B show that i need 14 turns on a
coupling transformer, when 2 primary turns are used, i.e. the loop
losses (at 475 kHz) is about 1 Ohm. I tried to find the C that is needed
to resonate the loop at 475 kHz but unfortunately my C-network
(0...1000nF + 1nF + 2.2nF + 4.7nF, switchable) does not cover the value
prcisely, it is just below 4.7 nF and above 4.2 nF. Next time...
Some images, as usual:
https://www.dropbox.com/sh/hjnkp3a60fyqk9v/AADRX9Hv2nAu7jYdzHHdRJ4Ja?dl=0 (nothing
special, just to share some RF stuff :-) ).
73, Stefan
Am 11.10.2015 23:15, schrieb DK7FC:
Hi all,
It was a wonderful day with UFB WX! Worked a bit in the tree for the
new RX system. Now a stable horizontal board is installed, to carry
the batteries which can be put there from now on. 3x 18 Ah is planned.
I also started to install 2 orthogonal loops out of 1.5 mm^2 cu wire...
A few images to give an imagination :-)
https://www.dropbox.com/sh/v6rqzbdzyqume8q/AAAVBhkMDEHo2ARW878XC881a?dl=0
73, Stefan
Am 29.09.2015 00:13, schrieb DK7FC:
Hi all,
For those who are interested, here are a few new images of my remote
RX installations in the new location.
https://www.dropbox.com/sh/4rdxmsly71xqsjw/AABnc6CddUTH3AuZPxpkgYzMa?dl=0
There is some good progress! Today i installed the waterproof box and
started the new Raspberry and established the WLAN link for the first
time. It runs all very well so far and i love to stay up there in the
tree on that hill/mountain, where stress noise is unknown!
Next steps are to order more batteries and solar modules and to build
a first MF receive antenna...
73, Stefan
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