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 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
john.rabson07@gmail.com
Researching history of RABSON, BLACKSHAW, GAUNTLETT, VERLANDER and
ROBSONNE
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