Hi Rik,
Of course, thats true ;-)
Especially when they use a short wire like a dipole for 40m. But that danger
can be reduced: You just need a loss resistance that is high enough, hi...
But: I don't think high voltages in a region of 10kV will kill you (in such a
application, say 200W and 20m of wire in 10m height und a loss resistance of
100 Ohm). It is due to the skin effect (with 50Hz it would look completely
different, hi) and due to the fact that if you touch the loading coil, the
resonance (and so the voltage) gets off-tuned. But surely there will be a hole
burned in the finger / skin that is aching and smelling ;-)
At work, when we present our institute on a tradeshow, we sometimes present a
series resonance circuit that is also operating in that frequency range. In
that circuit we have around 20...30kV and show a fluorescent lamp lightning
when touched at one end and so on. The power injected in this resonance circuit
is also abt 100W. Almost everyone got a spark in the finger in a moment of
unconcentration but you just feel a pain in the finger for that moment.
Anyway, I can renounce on it ;-)
73, Stefan / DK7FC
-----Ursprüngliche Nachricht-----
Von: [email protected]
[mailto:[email protected]] Im Auftrag von Rik Strobbe
Gesendet: Donnerstag, 10. Dezember 2009 11:07
An: [email protected]
Betreff: Re: LF: AW: TX-2200A
Stefan,
there is one good reason to limit the output
power 100W: more power could become lethal (high antenna voltages / currents).
The "black box operators" must be protected
against this danger, otherwise they might go QRT due to "natural selection" :-)
73, Rik ON7YD - OR7T
At 10:19 10/12/2009, you wrote:
>Warren, LF,
>Tnx for the info!
>I am not "afraid" that now many OMs come on the
>band who just bought their rig, like on HF. Even
>if you could buy a loading coil, you never will
>get qrv satisfactorily cause you always have to
>consider many things like the earth, the local
>noise reduction, the impedance transformation to 50 Ohm and so on.
>These OMs, even if they could buy a automatic
>tuner (that would not be easy to create as a
>commercial product) for LF, would be frustrated
>soon cause there are no contests and no 100s of
>stns calling on the band ;-) They would say "LF
>is dead, just nerving qrm" and would never get
>the fascination that we all experience.
>Finally I don't understand why this PA has just
>100W. To reach 1W ERP, most LFers have to apply
>1kW and more, so 100W is QRP on LF ;-). 1kW can
>easily be reached on LF without using expensive
>special transistors and drivers and ferrite
>cores. E.g. with one simple IRFP360 we can built
>a 1kW high efficiency calss d or e PA that costs not even 50€...
>These difficulties to get qrv is one part of the
>LF hobby and if they are solved, one can be glad
>even without doing 100s of qsos in one evening :-)
>
>Stefan / DK7FC
>-----Ursprüngliche Nachricht-----
>Von: [email protected]
>[mailto:[email protected]] Im Auftrag von Warren Ziegler
>Gesendet: Mittwoch, 9. Dezember 2009 16:30
>An: [email protected]
>Betreff: LF: TX-2200A
>
>Interesting new rig offered by Waters and Stanton - the TX-2200A 100
>Watt class D transmitter for 136kHz - VFO controlled with receiver
>muting.
>Made in Japan, relatively pricey though at 690 GBP!
>
>http://wsplc.com/pdf/TX-2200A.pdf
>
>
>
>73 Warren K2ORS
> WD2XGJ
> WD2XSH/23
> WE2XEB/2
> WE2XGR/1
|
