To: rsgb_lf_group@blacksheep.org
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From: Johan Bodin <jhbodin@tele2.se>
Message-ID: <9b95f193-7cc1-2033-54ec-fc287f687c6d@tele2.se>
Date: Tue, 18 Apr 2017 22:09:51 +0200
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Subject: Re: LF: A transductor for power regulation?
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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
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