Hi Rik, Paul, VLF,
In the 2nd test, the maximum power was 250W but the 0,48A is the estimated
average current (depending on the kite movement). The maximum current was about
0,55A, so the total resistance is about 825 Ohm. The coil has about 300 Ohm
(280 measured + the variometer part, estimated) so the surrounding losses are
about 500 Ohm.
Sorry that i cannot tell you exact values but this all is due to the kite
movement, you know. The ERP becomes even more an estimation since when the kite
changes it's angle, the effective height decreases + the antenna current. But
we still have high integration times and some dB S/N reserve for the most stns
and thus it obviously works...
BTW: A next step for my setup: I got the confirmation of my insurance, that is
needed to get the 300m (height) permission! ;-)
73, Stefan/DK7FC
________________________________
Von: [email protected] im Auftrag von Rik Strobbe
Gesendet: Fr 26.03.2010 21:35
An: [email protected]
Betreff: LF: RE: Question about ground impedance at 8.97 KHZ Stefan.
Paul,
I believe that Marcus reported a loss resistance ("ground loss") of about 1
kOhm.
For Stefan: based on 250W/0.48A the total loss resistance should be 1085 Ohm.
The coil (553mH, Q=82) counts for 380 Ohm, so "ground loss" is about 700 Ohm.
So unless you are living on solid rock or in a desert 70 kOhm seem very high.
Do you know the loss on 137kHz ? I guess that on 10kHz it will be 20 to 50
times more.
73, Rik ON7YD - OR7T
________________________________________
Van: [email protected] [[email protected]]
namens Paul A. Cianciolo [[email protected]]
Verzonden: vrijdag 26 maart 2010 19:38
Aan: [email protected]
Onderwerp: LF: Question about ground impedance at 8.97 KHZ Stefan.
Hello All,
Below is a quote from the Stefan's web page concerning his latest "Dreamers
Band" DX contact Congratulations again Stefan.
>From this information alone is it possible to calculate or know the antenna
>system impedance.
"100m Vertical wire antenna, coil/antenna voltage was abt 15kV rms, average
antenna current about 480mA, giving up to 1,7mW ERP. Applied power was up to
250W."
Pertaining to the coil "Technical and mechanical data: L=553mH, Q=82, R(DC)=283
Ohm; 0,4mm diameter enameled copper wire, about 1200 turns! Average diameter
0,55m, height abt 0,5m. So, about 2000m wire! :-)"
I have built a small impedance bridge that operates at 10 KHZ and shows my
sloping 170' wire as 70K Ohms. I can also see approx 500 PF that can be nulled
out using the bridge?
Can the 70K value possibly be correct? (3) 6' ground rods about 6' apart are
the ground... plus the electrical ground of the house.
I am hoping to attempt a local transmission on 9KHZ
Any information would be helpful.
Thank you
Paul
W1VLF
<<winmail.dat>>
|
