Hello Peter,
Tnx for confirmation.
Today i bought a new copper tube, circular, 1m diameter and 18mm tube
diameter and 1mm thickness (16 EUR). This time i realized excellent
contact of the caps dieectly to the tube. The first version used about
8cm (in sum) 1mm dia silver wire which may have caused some Q loss.
Addionally i want to use WIMA FKP-1 types now, 100nF/1250V. The new
version is very mechanically stable, i am glad and will show a photo later.
The Q measurement isn't done yet.
Now i have to concentrate on VLF...
So next week i'll give a new report.
73, Stefan/DK7FC
Am 17.06.2011 15:47, schrieb pws:
Hi Stefan,
You wrote:
...
I found the Q of the
loop is just 8! Is this normal? Which Q do others achieve, with a
similar antenna for 137 kHz?
...
Confirming your findings. In the late 90th I built a 2m-loop from 1"
coax ("Flexwell") for nulling out Loran-C splatter. I remember a
bandwidth of ~12-15 kHz => Q ~= 10 with 8.2uH/165nF.
http://www.qsl.net/df3lp/projects/lfloop/index.html
...
It is fascinating to null out s signal, which i have done the first
time now. I can reduce the signal of DCF39 by 25 dB by turning the
loop...
That's somewhat different to what could be found here. I observed very
sharp Nulls well>40dB below main lobes. May be due do the orthodox
"screened" design including the usual gap. But as you suggested that's only
true for pure groundwave reception. At VLF I'm observing the deepest null
of DHO38 (~200km; noon) at ~30deg. of elevation.
Good luck for tomorrow,
Peter, df3lp
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