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Re: LF: A transductor for power regulation?

To: [email protected]
Subject: Re: LF: A transductor for power regulation?
From: John Rabson <[email protected]>
Date: Tue, 18 Apr 2017 21:15:49 +0200
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I believe something like that is used at SAQ (Grimeton Radio) on 17.2 kHz as a 
saturable reactor for keying the transmission.

John F5VLF

> On 18 Apr 2017, at 18:18, DK7FC <[email protected]> wrote:
> 
> Hi all,
> 
> I'm just thinking about transductors and find them them quite fascinating 
> again. I read a bit Wikipedia and thought about the use as a steerable 
> transformer.
> Imagine you have a hard switching class D PA, H bridge or so. The output is a 
> constant voltage source and it is no problem to connect no load, as long as a 
> proper type of low pass filter is used.
> Then imagine a simple 1:1 ferrite transformer, 50 Ohm to 50 Ohm. The 
> transformer has a 3rd winding for a DC current (to compensate the AC 
> component transformed from the RF windings, 2 cores must be used, which are 
> in parallel for the RF and anti-serial for DC).
> Then i can saturate the transformer with the DC so the µr falls down to 1.
> With this arrangement i could build a linear PA out of a switch mode PA, even 
> a fast one, which avoids key-clicks, at least in QRSS-3 (you remember the 
> mode) or OP32 or even EbNaut on LF?
> Sounds like an interesting experiment at least. The question is how warm the 
> transformer would become when the RF output current is permanently reduced to 
> 50%.
> Has someone ever tried that on LF/MF?
> 
> 73, Stefan
> 

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Researching history of RABSON, BLACKSHAW, GAUNTLETT, VERLANDER and ROBSONNE






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