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LF: Max power was qrss 3/10

To: <[email protected]>
Subject: LF: Max power was qrss 3/10
From: <[email protected]>
Date: Tue, 15 Dec 2009 11:38:04 -0000
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In-reply-to: <38A51B74B884D74083D7950AD0DD85E828AC66@File-Server-HST.hst.e-technik.tu-darmstadt.de>
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From memory, and Ill stand to be corrected - the higher power stations Americas stations on 137Khz produced/are producing around 3W ERP (+ or minus 3dB for a ground constant Im having trouble with) from Marconis' and decent loops -  I cant recall anyone running much more save perhaps for VA7LF antipodes test  crowd (again apologies if Ive callsign wrong), or Ed and the Russian teams.
 
 
I know from the calcs and measurements this is about right for WD2XDW in Oklahoma which ran on a good day/week, with the wind behind around 40-50A of loop current, this from a Modded Purple Decca unit, again from a fading memory running around 1Kw output. I was about at my engineering limit with the V/m and loop current at this power in a suburban lot.
 
Man, Im getting RF lackitus having not shoved anything up a coax on LF for about 5 years Sad smile emoticon  Given my present licence a 10KW tx still would not  afford my max permit allowable ERP level on 137 with my planned Alaskan loop -  but never say never.
 
As far as noise sources are concerned from the PC - I really cant see anything on the frequencies of choice and solely limited by external out of my Faraday cage noise from the antennae =  now, that?s not to say the Dell SMPSU's don?t produce crud, and some of that does get back, no matter how much I choke and decouple -  but I must admit I have a box of them and choose my AC Power supply model for the band/bands of interest - and select one that doesn?t give me a sproggi where its not wanted. Oh for some time to get a method of running and decoupling all the lines/screen/mouse to and from the PC so its completely quiet.
 
Laurence
KL1 X  WE 2 X Pee Kew.
 
 

Sent: Tuesday, December 15, 2009 10:03 AM
Subject: AW: LF: "Gain" between qrss3 and qrss10?

Dear LF,

I have done some further thoughts/questions about the "gain" between the qrss modes.

If the "gain" or better said SNR between qrss30 and qrss3 is 10dB, so can I do a QSO to VK with 1W TX Power and an antenna efficiency of 1/1000 if I choose QRSS10000000000? That?s a litte jokingly formulated but you know what I mean. In other words, where are the limitations of this rule?

In CW I think that rule cannot be valid because a dot in CW (say 20wpm) is much shorter than 0,3s but to my experience the ?gain? compared to qrss3 is not even 10dB. Furthermore a PC must be seen as a source of QRM, especially when connected to the antenna system (e.g. for switching a tx relay with the qrs-programm) and RX (even when using a insulating transformer for the AF), and so it always brings a ?negative gain?, even when one uses 10s of ferrite cores?   

And: I always thought of the energy "waste" when applying 1kW (before 6 yrs when I became qrv with a much worse antenna) to the antenna and pumping 999,9W into the earth. But when I need 10x the time in qrss30 to do the qso with 100W, the needed energy is the same (compared to 1kW in qrss3). So, qsos could be done much faster if choosing 10x the power and stay in qrss3. The additional advantage would be, if I try to do a TA QSO I could just stay in the region of 137.7 and those who are qrv in qrss3 and only watch the qrss3-sector would get a nice signal and thus more fascination for the LF-hobby (I often think about the LWLs watching my transmission when no one is answering my call ;-)). In sum, the needed energy (=money) is the same but the needed time would be 10x less.

Of course, there would be some problems like partial discharges due to the high voltage at the antenna and for 10kW the kitchen stove must be connected in parallel, that could cause QRM with the XYL... ;-) But generally it would be interesting!?

What is the maximum power that is applied to an antenna yet? What have you heard yet? I have applied 1kW in a bad antenna (=> abt 100mW ERP), so 10kW would be possible when considering to stay in the legal limit. 10kW would be possible since one doesn't need a ferrite core that has to keep the power (in Class E mode). In USA it would be even more easy due to the fact that the 110V of the mains could just be rectified. Then I would take some STW12NK90Z in parallel and a IXDD414 and try it with 15A antenna current ;-)

Sorry, but in that hobby it is really easy to become euphoric?

 

73 and hope for fine qsos for us J

Stefan / DK7FC

 

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