Hi Stefan, MF
A resonating antenna is a blessing ! But a vertical antenna on top of a 80m building tower is double blessing ;-)
I have a very busy schedule this days, so had to finish the coil and variometer and installed it yesterday night in darkness
It was a shock to see >30 stations spotting my first WSPR Tx and on the third got FR5ZX. And the results of this
night produced also decodes in north America by VE1HF and WD2XSH
Even getting daylight decodes this morning by DH5RAE and looks like the signal is visible at Stefan grabber. Last decode
from DH5RAE at 10:48 UTC -26dB is amazing :-O
I'm also transmitting Opera8 as the PA is just sleeping now that there is a matched load on the other side (70W output)
The long ground line of the antenna at 80m being a thick water pipe down to building basements
is the key, as Markus predicted
Please let me recall his comments here:
But the good thing is that effective height will be much larger, because a significant part of the displacement current will not return to the roof but go the "long way" down to ground zero. This is also why a miniwhip on a pole receives larger signals.
Details depend on the exact geometry (eg. the relative thickness of the "mast"), but a good guess is taking the geometric mean between the height of the house and the effective height of the antenna itself if it was above flat ground.
In your case, this would be sqrt(80m*5.5m) = 21m, which is way above average compared to most amateur antennas. Radiation resistance would be 1.75 ohms, so in theory you'd need only 0.56 A to achieve 1 W ERP...
All the best,
Markus (DF6NM)
That was a BINGO Markus !
Next step is to accurately measure RF current. May be I'm well over 1W ERP ....
Thank you to all you guys to help me achieve this :-)
Ops ! CW QSOs .... Yes, I can do some CW but need refreshing it a little. We will make many FIRST as there has been some EA activity
before on MF but not sure if they worked many countries. Workload at job pressing this days and a trip to Mexico at the end of this month
Keep tuned ;-)
Hello Luis,
Your 11m vertical leaves a SNR of 0 dB here in WSPR now!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :-)
That means we can easily do a CW QSO!
| Timestamp |
Call |
MHz |
SNR |
Drift |
Grid |
Pwr |
Reporter |
RGrid |
km |
az |
| 2015-11-05 23:32 |
EA5DOM |
0.475793 |
0 |
0 |
IM98wn |
0.5 |
DK7FC/P |
JN49ik |
1398 |
27 |
| 2015-11-05 23:24 |
EA5DOM |
0.475793 |
-3 |
0 |
IM98wn |
0.5 |
DK7FC/P |
JN49ik |
1398 |
27 |
Do we want to try soon? Are you a CW man? It would be my first to EA on that band.
73, Stefan
Am 05.11.2015 23:59, schrieb VIGILANT Luis Fernández:
Wops !!
2015-11-05 22:48 EA5DOM 0.475790 -20 0 IM98wn 0.05 FR5ZX LG78pu 8796
New coil ! Antenna is finally on resonance ..... and seems to work ! ;-)
73 de Luis
EA5DOM
________________________________________
De: [email protected] [[email protected]] en nombre de DK7FC [[email protected]]
Enviado: jueves, 5 de noviembre de 2015 22:39
Para: [email protected]
Asunto: LF: FR5ZX WSPR again
Hi all,
The path is open again! Give it a try.
73, Stefan
