Hi While OCXO’s that have -170 dbc/ Hz specs are fairly common, they normally go deep inside a box of some sort. It’s a rare off the shelf device that takes in the output of a distribution amp *and* requires that sort of phase noise.
What’s your target device(s)? Why do I ask? Well, a device that has a -170 dbc floor combined with a -170 dbc oscillator will give you -167. A device with a -200 dbc floor will still “degrade” a -170 dbc oscillator. That’s a fairly big change in circuit complexity (and cost) for a 2.9 something db improvement. The list of devices that might make it worth spending (say) a few hundred dollars a channel versus under a buck a channel is pretty short. That may put a bound on this. One example may help: If you are running phase noise testing, forget about multi channel distribution amps. They will add a ground loop(s) / pickup loop(s) that you will be fighting forever and ever. Do that sort of stuff straight off the oscillator. There is no rational amount of money (ummm …. errrr … how much do you have?) you can spend to get around this. A second (or eighth) oscillator is cheaper than even some of the simple approaches that don’t work very well. The type of OCXO you are talking about is a < $50 item on eBay. Bob > On Nov 23, 2014, at 9:17 PM, Bill <[email protected]> wrote: > > Thanks to all for the response but the distribution amp additive noise can be > a real problem since the 10 MHz to be distributed is -170 dBC/Hz at 10 KHz > and needs to be preserved if at all possible. > > BTW, the Ettus Octobox doesn't have a spec for additive phase noise, so > that's out. > > Again thanks...Bill > > -----Original Message----- > From: time-nuts [mailto:[email protected]] On Behalf Of Bob Camp > Sent: Sunday, November 23, 2014 1:09 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Low Additive Phase Noise 10 MHz Amps > > Hi > > For any “real world” source being distributed, simple high speed CMOS buffers > will not add enough noise to matter at 10 MHz. That of course also assumes > that the target gear is the normal bunch of instruments that we all play > with. > > Bob > >> On Nov 23, 2014, at 11:47 AM, Bill <[email protected]> wrote: >> >> What's the latest opinion (data) on available low additive phase noise >> 10 MHz amplifiers for 10 MHz distribution? >> >> >> >> Regards and thanks.Bill >> >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
