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Date: Thu, 10 Dec 2009 11:42:17 +0100
Message-ID: <38A51B74B884D74083D7950AD0DD85E828ABE9@File-Server-HST.hst.e-technik.tu-darmstadt.de>
In-Reply-To: <20091210100700.32DEC31E703@smtps01.kuleuven.be>
Thread-Topic: LF: AW: TX-2200A
Thread-Index: Acp5gW2FA4OKFL6sSFWMbcvN5Pw+iAAAVBEw
From: =?windows-1258?Q?Stefan_Sch=E4fer?= <schaefer@hst.tu-darmstadt.de>
To: <rsgb_lf_group@blacksheep.org>
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Subject: AW: LF: AW: TX-2200A
Sender: owner-rsgb_lf_group@blacksheep.org
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Reply-To: rsgb_lf_group@blacksheep.org


Hi Rik,=20
Of course, thats true ;-)
Especially when they use a short wire like a dipole for 40m. But that dang=
er 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 suc=
h a application, say 200W and 20m of wire in 10m height und a loss resista=
nce of 100 Ohm). It is due to the skin effect (with 50Hz it would look com=
pletely 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 presen=
t a series resonance circuit that is also operating in that frequency rang=
e. In that circuit we have around 20...30kV and show a fluorescent lamp li=
ghtning when touched at one end and so on. The power injected in this reso=
nance 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.=20
Anyway, I can renounce on it ;-)
73, Stefan / DK7FC


-----Urspr=FCngliche Nachricht-----
Von: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacks=
heep.org] Im Auftrag von Rik Strobbe
Gesendet: Donnerstag, 10. Dezember 2009 11:07
An: rsgb_lf_group@blacksheep.org
Betreff: Re: LF: AW: TX-2200A

Stefan,

there is one good reason to limit the output=20
power 100W: more power could become lethal (high antenna voltages / curren=
ts).
The "black box operators" must be protected=20
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=20
>band who just bought their rig, like on HF. Even=20
>if you could buy a loading coil, you never will=20
>get qrv satisfactorily cause you always have to=20
>consider many things like the earth, the local=20
>noise reduction, the impedance transformation to 50 Ohm and so on.
>These OMs, even if they could buy a automatic=20
>tuner (that would not be easy to create as a=20
>commercial product) for LF, would be frustrated=20
>soon cause there are no contests and no 100s of=20
>stns calling on the band ;-) They would say "LF=20
>is dead, just nerving qrm" and would never get=20
>the fascination that we all experience.
>Finally I don't understand why this PA has just=20
>100W. To reach 1W ERP, most LFers have to apply=20
>1kW and more, so 100W is QRP on LF ;-). 1kW can=20
>easily be reached on LF without using expensive=20
>special transistors and drivers and ferrite=20
>cores. E.g. with one simple IRFP360 we can built=20
>a 1kW high efficiency calss d or e PA that costs not even 50=80...
>These difficulties to get qrv is one part of the=20
>LF hobby and if they are solved, one can be glad=20
>even without doing 100s of qsos in one evening :-)
>
>Stefan / DK7FC
>-----Urspr=FCngliche Nachricht-----
>Von: owner-rsgb_lf_group@blacksheep.org=20
>[mailto:owner-rsgb_lf_group@blacksheep.org] Im Auftrag von Warren Ziegler
>Gesendet: Mittwoch, 9. Dezember 2009 16:30
>An: rsgb_lf_group@blacksheep.org
>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