Message-ID: <004101ccbf38$7ee0fe90$0401a8c0@xphd97xgq27nyf>
From: "mal hamilton" <g3kevmal@talktalk.net>
To: <rsgb_lf_group@blacksheep.org>
References: <CAA8k23Rn9WpQM3Ukf=cq5-bLmWy+o4SEsH2abf7cAX=BpLWExQ@mail.gmail.com> <op.v6k16ktpyzqh0k@pc-roelof> <033201ccbcab$5c5fe640$1502a8c0@Clemens04> <op.v6mtuugnyzqh0k@pc-roelof> <000901ccbcc4$42768fe0$c763afa0$@com> <4EECC1E8.4000806@iup.uni-heidelberg.de> <002c01ccbd6f$572761c0$0401a8c0@xphd97xgq27nyf> <39D91133A64A480596FBAA4395D85812@JimPC> <007901ccbd9e$69fe2ed0$0401a8c0@xphd97xgq27nyf> <08C805D2A1C04E64836275C632577CF2@JimPC> <000901ccbe3e$31cd2700$0401a8c0@xphd97xgq27nyf> <BD04607BFB844A3F85A112052DEA2EF1@JimPC> <4EF07E9B.2070401@iup.uni-heidelberg.de>
Date: Tue, 20 Dec 2011 16:57:45 -0000
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Subject: Re: LF: Re: Re: Re: TX system at DK7FC, schematic
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Stefan, Jim es Co
I can understand the problem of going off Resonance with a large Inductor
and short wire in Stefans case. This happens on 160m Mobile where the
Loading coil is large and the top section only a a metre or so long,  when
passing close to large vehicles or trees on country roads or sudden changes
in WX
With my small loading coil less than 0.5 mH the WX has less influence on
Resonance and if it does its only one TAP up or down to rectify the
situation
I do however see some fluctuations in a GALE when the wires move about but
that is short lived although it might show up as QSB at the RX end.
My system gives vy little trouble, low maintainence  and is stable. The same
applies on MF. Now using Decca equipment for both bands and all H/B
Transmitters/amplifiers are kept in reserve.Decca is fairly fail safe when
handled properly




mal/g3kev



----- Original Message -----
From: "Stefan Schäfer" <Stefan.Schaefer@iup.uni-heidelberg.de>
To: <rsgb_lf_group@blacksheep.org>
Sent: Tuesday, December 20, 2011 12:24 PM
Subject: Re: LF: Re: Re: Re: TX system at DK7FC, schematic


>
> Am 20.12.2011 00:49, schrieb James Moritz:
> > [...]
> > With a high loaded-Q antenna, small changes in reactance result in a
> > large mismatch, and the continuously-variable variometer inductance
> > allows precise adjustment of matching. If you used some arrangement of
> > tapped coils instead, the inevitable slight errors in inductance
> > caused by only being able to adjust in discrete steps would probably
> > result in a greater reduction in antenna current than that caused by
> > variometer losses.
> > [...]
> >
> Exactly.
> That's what happend tonite and in the morning. The first time in the
> season it is snowing here and so my system got strongly out of
> resonance, reducing the TX power by about 10 dB. So i hardly expect TA
> reports from this night. A pity, since we are in the best time of this
> season...
> I really need the automatic variometer now. The phase meter (M0BMU
> design) already works very well. Hope to get it ready during this week.
> A work that makes fun!
>
> 73 all,
>
> Stefan/DK7FC
>
>
>