Jitter & Lab Noise

[kevin1980]

We are doing some jitter measurements at 2.48 MHz and 19.4 MHz but our power supplies (Agilelent or XT 15-4) are giving too much noise to properly perform the tests. Does anyone know of any good filters that can be purchased to clean up the signal? Or a type of isolation chamber to isolate the test from all the other lab equipment running at the same time? Or would you suggest just using a Battery with a regulator?

Thanks in advance for any assistance

 

[TWW]

Are the power supplies you are using the older linear or the switched supply type? The older type (with the back breaking transformers.... heavy!) typically will produce less noise. I have ran in these problems in the past and they can be quite flusterating. A battery would be the last resort but would work if the noise originates from the DC supply). additionally the pick-up from fluorscent lights that have solid state ballist can be an issue, if you are using high impedance probes. 50 ohm probes/scope impedance reduces the trash significantly. If you use incandelscent lights that reduces the ambient. To filter the DC you can scrape up chokes and bypass caps of various sizes to shunt the high frequency noise (lowpass filter) (if is is coming from the power supply)