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Re: LF: [TECH] Help needed on toroid trasf. construction

To: [email protected]
Subject: Re: LF: [TECH] Help needed on toroid trasf. construction
From: "Brian Rogerson" <[email protected]>
Date: Mon, 11 Jun 2001 12:03:31 +0000
In-reply-to: <[email protected]>
References: <[email protected]>
Reply-to: [email protected]
Sender: <[email protected]>
May I add a request please, I am looking for the design of an "ultimate"
3dB splitter for 136KHz with good characteristics to well down below

73, Brian

At 13:34 11/06/01 +0200, you wrote:
Hi all,
 I need some words of wisdom and a bit of help about the
construction of a small toroid transformer.

First the antefact : I swapped recently my TS-850 for a TS-950SDX,
a very fine radio, but much less sensitive on the LF band than the TS-850.
Looking at the schematics, and doing some filter simulation with
Electronic Workbench, I think to have found the culprit, i.e. L3, a small
toroidal transfomer, with ratio 1:4, which is inserted in the signal path,
after the input attenuator, and before the filters bank. With all
its  response at 136kHz leaves much to be desired. The TS-850 doesn't
have any such transformer, the signal goes straight to the filters.

So I have decided to replace it. Looking in the MiniCircuits catalog, I have
found what seems to be the ideal replacement, the T4-6T-KK81 model, which
has a -3dB response from 10kHz to 100MHz. Problem is that this transformer
is not carried in stock by the Italian distributor, and both they and the
MiniCircuits sales office have a minimum quantity amount for an order.

At this point the only choice is to build it myself. And this is were your
help could
come in my rescue. I need to know what your experiences are in building
such a wideband kind of transformers. What is the best type of material,
caveats to not forget, optimal number of turns, you name it.

TNX for any help,

73  Alberto  I2PHD

73 Brian     CT1DRP     IN51QD     41 09 58N  08 39 11W

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