LF: RE: MF CW now

[VIGILANT Luis Fernández <luis@vigilant.es>]

Sorry Stefan

 

Not at QTH now. That's the good side of digital modes. They can run alone at home, like my fish tank :-)))

 

The antenna is not perfectly matched. I'm running the PA at shack and have 30m coax. I adjust the variometer by hand

with the analyzer and when measuring down in the shack it is not the same. But anyway it makes the job

No output transformer yet, just the coil and another small one as variometer inside

 

PA output is 60V RMS over 50R load. I'm measuring 74V now because load is not perfect. The power supply now at 13V5 and 7A  

So I don't think there are 100w but probably closer to 70w

 

Will be interesting to know exactly which is the antenna current

 

And yes, legal limit is 1W. But we are all, ALWAYS willing to reach that .... we poor hams ! ;-) 

 

 

73 de Luis

EA5DOM

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De: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] En nombre de DK7FC
Enviado el: viernes, 06 de noviembre de 2015 17:40
Para: rsgb_lf_group@blacksheep.org
Asunto: LF: MF CW now

Luis,

I see you are now TXing in WSPR again. So you are at home and on air. Maybe we can try in CW now? I will go to call CQ! on 472.2 kHz. Maybe it is a good time to try now during our sunset!?

73, Stefan

Am 06.11.2015 17:29, schrieb DK7FC:

Hi Luis,

What did i say!?! You can get +40 dB over the horizontal loop and +20 dB over the unloaded vertical :-) Also your PA is more relaxed now i think.
You are by far the strongest station in EA so far on MF and it was a first transatlantic decode i think, for EA.
70W? Thought it is a 100W PA. So the matching isn't accurate yet? Or do you run less supply voltage?
I also saw the daytime decodes by DH5RAE. A challenge for my tree project! :-)
Do you have some further ideas now what to do with the antenna or is the project finished now? :-)

OK about Markus' explanations. I think your antenna is something like a short dipole, with one leg close to ground, with an excentric feed point and all this is rotated by 90 deg! :-)

73, Stefan

Am 06.11.2015 12:07, schrieb VIGILANT Luis Fernández:

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 ;-)

 

73 de Luis

EA5DOM

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De: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] En nombre de DK7FC
Enviado el: viernes, 06 de noviembre de 2015 0:41
Para: rsgb_lf_group@blacksheep.org
Asunto: LF: EA5DOM

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
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De: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] en nombre de DK7FC [selberdenken@posteo.de]
Enviado: jueves, 5 de noviembre de 2015 22:39
Para: rsgb_lf_group@blacksheep.org
Asunto: LF: FR5ZX WSPR again

Hi all,

The path is open again! Give it a try.

73, Stefan