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Re: LF: RE: Analog oscillators

To: [email protected]
Subject: Re: LF: RE: Analog oscillators
From: "Roelof Bakker" <[email protected]>
Date: Fri, 06 Jul 2012 09:39:44 +0200
In-reply-to: <[email protected]>
References: <[email protected]> <7E7DFBB4D102A04DB5ADC88D66628A4A0FAB99CC@ICTS-S-MBX5.luna.kuleuven.be> <[email protected]> <[email protected]> <op.wgzqhb2nyzqh0k@pc-roelof> <[email protected]>
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Hello Stefan,

A FT-37-43 ferrite toroid is not suitable for a VFO as you found.
Powdered iron cores from Amidon are much better in this regard.
From the common available parts -6 material has the lowest temperature coefficient,
-7 is slightly better:

T-50-2: 95 ppm/C
T-50-6: 35 ppm/C
T-50-7: 30 ppm/C

The temperature coefficient does not vary with the size of the toroid.

There are tricks to achieve mechanical stable windings on a Toroid.
One is to wind it as tight as you can and than place the coil in boiling water for 10 minutes.
This removes the mechanical stress and the winding settles down.

73,
Roelof, pa0rdt


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