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Re: LF: Osc drift (TCXO)

To: [email protected]
Subject: Re: LF: Osc drift (TCXO)
From: [email protected]
Date: Sat, 30 Nov 2002 08:33:18 EST
Reply-to: [email protected]
Sender: <[email protected]>
Hi,

In a message dated 11/29/02 7:03:23 PM GMT Standard Time, [email protected] writes:

Layout of the IIG oscillator/synthesizer board is quite different from the
II, also the TCXO for the IIG is much bigger and a different part number.
The TCXO for the II is claimed to be a "numerically-controlled" type, that
for the IIG is not. Does anyone know the difference? I thought all tcxo's
were just thermistor-controlled varactor diodes in series with the crystal.


I think the idea of a numerically-controlled TCXO is having an internal ADC digitizing the NTC voltage, convert it in a calibrated nonvolatile lookup-table and then use a DAC for the varicap. Depending on digital resolution, this concept can be prone to a stepwise response to gradual temperature changes, possibly resulting in a sawtooth FM pattern.

73
Markus, DF6NM
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