[time-nuts] Re: DIY Low offset Phase Noise Analyzer

[Erik Kaashoek]

Hi David,
Let me explain the DIY "measurement instrument"
DOCXO into LO port of a mixer, DUT into RF, IF port with low pass filter 
to both steer the Vtune of the DOCXO and into an opamp to amplify 
1-100kHz into PC audio input. On PC audio spectrum analyzer.
So yes, the limiting factor is the measurement instrument, probably the 
opamp
Further improvements of the setup has reduced the noise level at 10kHz 
offset to -145dBc/Hz so the phase noise of the DOCXO plus the AR60 is at 
least -145dBc/Hz at 10kHz offset. If the DOXCO is, as the spec states, 
-150dBc/Hz at 10kHz offset that the AR60 can not be above -145dBc/Hz at 
10kHz.

On 4-7-2022 12:01, David C. Partridge via time-nuts wrote:
> Are you sure the PN floor of the measurement instrument isn't the limiting factor?
>
> David
>
> -----Original Message-----
> From: Erik Kaashoek via time-nuts <time-nuts at lists.febo.com>
> Sent: 04 July 2022 10:14
> To: time nuts <time-nuts at lists.febo.com>; Erik Kaashoek <erik at kaashoek.com>
> Cc: Erik Kaashoek <erik at kaashoek.com>
> Subject: [time-nuts] DIY Low offset Phase Noise Analyzer
>
> :
>
> At 10kHz offset the Phase Noise of the DOCXO should be -150dBm but
> unfortunately either the noise of the ultra low noise opamps or the
> Phase Noise of the AR60 is almost 20dB higher.
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