Message-ID: <4F25EA3E.60205@charter.net>
Date: Sun, 29 Jan 2012 19:54:22 -0500
From: John Andrews <w1tag@charter.net>
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Subject: Re: LF: Re: WOLF??
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Jim,

And for the ultimate in TA DX, consider my little "TAG" Lowfer setup on 
185.800 kHz in Maine. The 1-watt Class D PA is fed with a keyed 24V 
power supply with a sine-shaped rise/fall time of about 5ms. This 
greatly reduced clicks around the QTH. The mice that hang around the 
exciter box with the nice proportional oven haven't offered any 
preference. But in the winter, they seem to appreciate WOLF, which is 
strange from a predatory point of view.

JA

> Leaving out the envelope shaping results in "key clicks" when the phase
> transitions occur, and a wider bandwidth. One can ask the question "does
> this matter?" Probably yes it does if you are running 1kW on 136k. But
> there are plenty of clicks on VLF already, so I doubt anyone would
> notice at 9kHz ;-) Certainly, the US "Lowfer" LF stations with their 1W
> TXs used Wolf successfully with class D or E amplifiers and no envelope
> shaping.
>
> You could use a linear PA to generate the envelope-shaped signal. In the
> 2001 tests I used the Decca class D PA with the DC supplied via a high
> level series modulator, in conjunction with a phase modulated carrier,
> to generate the amplitude-modulated BPSK. The transmitter used dedicated
> waveform-generating hardware, with the binary message code burned onto
> an EPROM. With WOLF GUI, at least changing the transmitted message
> should be quicker...
>
> Cheers, Jim Moritz
> 73 de M0BMU
>
>
>
>
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