Message-ID: <424A7A39.2020201@wp.pl>
Date: Wed, 30 Mar 2005 12:06:49 +0200
From: Marek SQ5BPM <sq5bpm@wp.pl>
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To: rsgb_lf_group@blacksheep.org
References: <001301c533a6$e3f37c60$2102000a@ibm> <004701c533c7$5f9b2a00$546ca450@preinstapdq0tf> <000801c533ce$756d3ce0$2102000a@ibm> <42494D98.8060506@wp.pl> <005201c534b6$d8a34c80$89618351@w4o8m9>
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Subject: Re: LF: Re: More on cores...
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Dear all,

Thanks for all the replies, both sent to the group and privately, I feel 
I know a little more now :)

As for the question below, it's a current-switching circuit then, the DC 
is fed via a choke. As I wrote earlier, changing inductance of this coil 
does not change a lot, I settled at more or less the same inductance as 
one half of the primary winding.

The output filter coils are made of air cores (screened), with 
inductances and capacitances same as in YXM's circuit (54uH x2 + 
12/27/12nF). This seems to work well.

I am definitely going to make a new version of the TX in a bigger case 
so that the influence of different parts of the TX is minimised and ad 
hoc changes are easier than now. At the moment even switching the 
secondary tap is at least 5 minutes of work...

73! Marek SQ5BPM

James Moritz wrote:

>Dear Marek,
>
>OK on what people have said about the transformer design. The transformer is
>one thing - but what about the rest of the circuit you are using - in
>particular, what kind of output filter does the circuit have connected to
>the transformer secondary, and is it a voltage-switching (centre tap of
>primary decoupled to ground) or current-switching (centre tap fed with DC
>via a choke) circuit ?
>