[time-nuts] How to measure regulator noise?

Didier Juges didier at cox.net
Sun Jan 6 15:29:11 EST 2008


John,

Have you looked at the voltage with a scope at the same time the analyzer is
running?

Could the coupling capacitor be leaking ?

Didier

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of John Ackermann N8UR
> Sent: Sunday, January 06, 2008 2:18 PM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] How to measure regulator noise?
> 
> I'm experimenting with some low noise regulators, and want to 
> do some meaningful measurements to compare them (and 
> hopefully compare to published specs).
> 
> I have an HP 3561A FFT analyzer, which can probably be beaten 
> these days by a sound card, but has the advantage of absolute 
> calibration and GPIB to dump data.  I also have a very low 
> noise 40dB audio amplifier that covers <10 Hz to >100 kHz.
> 
> I've tried just looking at the regulator output with the 
> analyzer, with and without the amp, but am not sure what I'm 
> seeing.  In particular, even with a capacitor to block the 
> DC, the analyzer indicates "Overrange" at a reference level 
> below -5 or so dBV.  That puts most of the noise spectrum 
> below the bottom of the screen.
> 
> Any suggestions on an appropriate test configuration, and on 
> how to get readings that directly relate to the root-Hertz 
> value shown by regulator data sheets?
> 
> Thanks,
> 
> John
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, 
> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> No virus found in this incoming message.
> Checked by AVG Free Edition. 
> Version: 7.5.516 / Virus Database: 269.17.13/1211 - Release 
> Date: 1/6/2008 11:57 AM
>  
> 

No virus found in this outgoing message.
Checked by AVG Free Edition. 
Version: 7.5.516 / Virus Database: 269.17.13/1211 - Release Date: 1/6/2008
11:57 AM
 




More information about the time-nuts mailing list