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Re: LF: Re: Power of Donebach 153kHz TX

To: [email protected]
Subject: Re: LF: Re: Power of Donebach 153kHz TX
From: [email protected]
Date: Tue, 30 Jul 2002 18:27:56 EDT
Reply-to: [email protected]
Sender: <[email protected]>
Hi Dick and the group,

I am pretty sure Donebach uses some form of controlled carrier modulation,
apart from the phase modulation mentioned by Walter.<<

Yes, DLF does use "dynamic AM" modulation, with up to 3dB carrier reduction at low audio levels. The variable carrier level is generated along with the audio in the control circuit of the Telefunken PANTEL switched-mode modulator stage, operating at 54kHz. During normal daytime operation, both transmitters are combined, and the carrier power varies from about 250 to 500 kW. The two-mast antenna system then has a directional minimum of nominally minus 3dB /monopole towards Romania (SW, abt. 110°), and a gain of about 2dB to the NW. So with only one TX operational (125...250kW), one would expect 200...400kW EMRP towards the Netherlands. - As Walter has said, at night regularly a single TX is used, and the antenna system is fed differently to provide a deeper null with -10dB vs. +2dB directivities.

73 de Markus, DF6NM


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