Message-ID: <58F67DF9.9070502@posteo.de>
Date: Tue, 18 Apr 2017 22:58:33 +0200
From: DK7FC <selberdenken@posteo.de>
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In-Reply-To: <9b95f193-7cc1-2033-54ec-fc287f687c6d@tele2.se>
Subject: Re: LF: A transductor for power regulation?
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Status: O

Hello Johan,

Very nice, thanks for the link!

Here is another link which explains something, also with a historic 
background.
https://de.wikipedia.org/wiki/Pungs-Drossel
The site is only in German but maybe it translates good in 
https://translate.google.com/translate?hl=de&sl=de&tl=en&u=https%3A%2F%2Fde.wikipedia.org%2Fwiki%2FPungs-Drossel

73, Stefan

Am 18.04.2017 22:09, schrieb Johan Bodin:
> John is right. The transductors at SAQ can be seen in this photo in 
> google street view:
>
> https://www.google.se/maps/@57.1139306,12.4045874,3a,75y,221.02h,87.43t/data=!3m7!1e1!3m5!1sA9thq95lEHf5u-4IrG4StQ!2e0!3e2!7i13312!8i6656 
>
>
> The transductors are the big "rolls" at the top and were called 
> "magnetic amplifers" in SAQ documentation from the mid 20's.
>
> 73 de Johan SM6LKM
>
>
> John Rabson wrote:
>> 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 <selberdenken@posteo.de> 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 皴 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
>>>
>> john.rabson07@gmail.com
>>
>> Researching history of RABSON, BLACKSHAW, GAUNTLETT, VERLANDER and 
>> ROBSONNE
>>
>>
>>
>>
>>
>>
>
>