Message-ID: <5CF75E2C.7090502@posteo.de>
Date: Wed, 05 Jun 2019 08:16:12 +0200
From: DK7FC <selberdenken@posteo.de>
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To: rsgb_lf_group@blacksheep.org
References: <6DB8451D7F3D3947A5918808A59621EA31596319@servigilant.vigilant.local>,<1506314235.20190531170414@gmail.com> <6DB8451D7F3D3947A5918808A59621EA5BEB6D86@servigilant.vigilant.local> <5CF57D0B.8060906@posteo.de> <6DB8451D7F3D3947A5918808A59621EA5BEB90E3@servigilant.vigilant.local>
In-Reply-To: <6DB8451D7F3D3947A5918808A59621EA5BEB90E3@servigilant.vigilant.local>
Subject: Re: LF: LF daylight test close to the north hemisphere solstice
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Hi Luis,

No, i just mean a second transformer between PA and the other 
transformer, into the coax line. A simple 1:1 ferrite transformer.
Your ground conductors into and arround the building are a part of the 
antenna, obviously causing a high voltage between that ground and your 
shack ground. All you can do is reducing the coupling impedance 
(capacitive) and the electrical field strength. A well dimensioned 1:1 
transformer will provide a good decoupling and low losses. The improved 
decoupling may change the resonance a bit (because your shack earth is 
less a part of the system taking RF currents), so a retuning is 
required. Hopefully your shack earth is not the dominant part of the 
antenna ground :-) The less it is a part of the ground system, the less 
is the detuning of the antenna when inserting the second transformer.

73, Stefan

Am 04.06.2019 10:59, schrieb VIGILANT Luis Fernández:
>
>> This week I should have to rework the PA output transformer. The one
>> in use lacks good isolation and get arcs when pushing it a bit. All
>> going Ok may be I can still rise some dB