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Date: Mon, 25 May 2015 20:06:30 +0200
From: DK7FC <selberdenken@posteo.de>
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Subject: Re: LF: EA5DOM <crazy> vertical
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Hi Luis,

Am 25.05.2015 19:17, schrieb VIGILANT Luis Fernández:
> So, this bands simple DO NOT EXIST as ham bands
> for most of the ham community
>    
I agree. But this makes it a real interesting segment of the hobby. And 
this is why we are a small group of crazy guys running several kV on 
their antennas :-)

> Actually Ramiro, EA4NZ has made a great improvement in his urban Rx dealing with lot of QRM. Will be very helpful
> to publish his work. So others can benefit from his experience
>    
Yes i saw he is now getting very good results. A few weeks ago i have 
been close to the detection limit (the lower one :-) ) and now he shows 
SNRs in the + range.
Worth to share his results.

>> This is exactly why i say that there must be QRO stations on the band!!!!!!!!! ...to generate a first detectable signal for a>(still) sub-optimal RX-system!! :-)
>>      
> Absolutely !
> People first try to Rx something. If there is nothing heard they automatically hang the "Out of order Band"
> and QSY to 80,40m, etc. I bet this happens to 160m too. But the most amazing is that this concept is also
> applied to VHF and microwaves. "Didn't heard anything"."There is nobody there" .... %-)
>    
Right. But this fact is permanently ignored by people who don't like 
high power for some reasons ;-) They have to ignore it for themselves, 
otherwise their own argumentation (that QRO is a waste of energy and 
only causes QRM to others) wouldn't make sense. They would then have to 
correct their view, that there are many stations on the band (maybe 
EA4NZ) receiving them just because there was a detectable signal at the 
beginning...

> U3 outputs the signal from a DDS or actually in the new version using 
> a SiLabs PLL. There is sine and square output
> Bet you are describing the same system used in a softrock to get a bi-fase signal from the antenna. See T1
> http://fivedash.com/resource/LiteIISchematic.pdf
>    
Yes, exactly.
Here is the link to my small PA that is use for MF, 
https://dl.dropboxusercontent.com/u/19882028/MF/100W-475KHZ-PA.png and 
https://dl.dropboxusercontent.com/u/19882028/MF/DK7FC%20472%20kHz%20PA%2015W%2B100W.JPG
It generates the 2 phase signals by a different way, out of a 4f signal. 
But i have added a "stereo input" using a 3.5mm headphone jack to apply 
the 2 phase signal so i can also run WSPR and other FSK modes. This 2 
phase signal is coming from a 7667 and such a ferrite transformer. I 
just show you the link to get some more impressions how you can build up 
the driver and FETs and transformer...

> I mean RF antenna current. As my measure is not calibrated I just tell 
> you in therms of gain (8 times)
Hm, 8 times the current is 64 times the RF power. So either you run QRPP 
before or i can understand why the FET blew up quickly :-)
Or maybe the wave form was not sinuosuouildilan (you know...) any more 
and the reading became wrong...

> Are you planning to produce a PCB for your 100w PA ??
No. Not a good idea for me since i like to have a lot of free time and i 
already have enough money...
There are some TX to buy, like http://www.jumaradio.com/juma-tx500/  (i 
assume it can also TX on 475 kHz, not only on 500 kHz) but it only 
generates 50W and is quite expensive i find.

> Last IRF510 of the batch running tonight. Lets see if all goes Ok at 14V
>    
R. Fine!
73!
Stefan