Message-ID: <5C5FF6F8.7000007@posteo.de>
Date: Sun, 10 Feb 2019 11:03:36 +0100
From: DK7FC <selberdenken@posteo.de>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3
MIME-Version: 1.0
To: rsgb_lf_group@blacksheep.org
References: <168d6970d7b.marcocadeddu@tin.it>
In-Reply-To: <168d6970d7b.marcocadeddu@tin.it>
Subject: Re: R: Re: VLF: in VK?
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org

Hi Dimitris, VLF,

Am 10.02.2019 09:47, schrieb marcocadeddu@tin.it:
> (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