Hi Dimitris, VLF,
Am 10.02.2019 09:47, schrieb [email protected]:
(RF? it is almost DC hihi)
Ehm, no, it is almost LF! 29.5 kHz, you can't even hear that. The other
(left) side of the audio spectrum that you can't hear too, maybe
something below 30 Hz, that's close to DC :-)
Am 09.02.2019 23:58, schrieb Dimitrios Tsifakis:
The unexpected losses are not just the
capacitors (their contribution is probably small). It is also the
coaxial cable that I used between the antenna feedpoint and the
amplifier.
How long is that cable? And didn't you use a ferrite transformer to
match the loop to the amplifier? If it is a normal audio amplifier that
expects a 4 Ohm load, then maybe you don't need one, but then you should
place the amp close to the loop, without the coax cable inbetween. If
the loop is far from the house and you want to stay the amp into the
shack, then use 2 ferrite transformers to transform up to 50 Ohm and
then down to the antenna impedance again. I would place the amp in the
shack and monitor voltage and current there using a scope. Then you see
their ration (Impedance) and product = power (at resonance). I would
first build a transformer that matches 4 Ohm to 50 Ohm for example, then
use the cable, and then a transformer from 50 Ohm to the feedpoint
impedance of the tuned loop.
In the end, such a closed loop will not perform as good as a ground
loop. You will get much better results when connecting two of these
little ponds beeing some hunderet meter distant. The current will be
lower and so the capacitors will be less stressed.
BTW is your ground very dry? you could even try a dipole on the ground
for the 630m band. A full size dipole. It would be able to carry much RF
power :-)
And what about a vertical antenna?
Oh i see, i would spend several hours per day there building antennas!
73, Stefan
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