Re: LF: Osc drift

[G0MRF@aol.com]

In a message dated 11/29/02 7:03:23 PM GMT Standard Time, blanch@pncl.co.uk 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.


There is a remote possibility that you may have a PLL frequency synthesiser and not a crystal at the frequency that you think.
I recently tried to buy a crystal oscillator module at 70 something MHz only to be told that they were OK for everything except demanding communication applications.
It appears that they frequently have a standard PLL module and just programme it for whatever frequency the customer wants. It's then sold as an Oscillator module, which does contain a crystal, it's just the reference xtal for the internal PLL.
That may go some way to explain the jitter.......or not as the case maybe.

73

David  G0MRF   www.g0mrf.freeserve.co.uk