My approach in progress is LVPECL driver from the master clock to a low cost "clock cleaner" PLL with a low phase noise VCXO (mine are crysteks and abracon depending on what I felt like at the moment).
Does that sort of approach match your requirement? It isn't as low cost as a dist amp but the results should theoretically be quite good. I'm not instrumented to REALLY test the fine edges of performance but... On Sunday, November 23, 2014, Bill <b...@hsmicrowave.com> wrote: > Hi Bob, > > Thanks for your comments. > > The devices in my lab that can benefit from the low phase 10 MHz source > are 1) the spectrum analyzer(s), 2) a Comstron direct synthesizer, 3) the > synthesized signal generators and the test source(s) used to drive > microwave multipliers and signal sources. All these devices will see the 10 > MHz phase noise (improvements) within the narrowest PLL the devices use. > > After spending "bucks" for a low noise 10 MHz source, I can't afford to > use one for each instrument. Besides it would hurt to go through the > trouble of buying a low phase noise 10 MHz reference and lose it in a poor > distribution amplifier(s). Also, the advantages of running all instruments > from the same 10 MHz source are well known. > > So while I was hoping to short circuit some of the design/prototyping > effort in the hopes someone on this thread had been there, I'll just "hit > the books" and do some prototyping and noise testing and see what I come up > with. > > Regards...Bill > > -----Original Message----- > From: time-nuts [mailto:time-nuts-boun...@febo.com <javascript:;>] On > Behalf Of Bob Camp > Sent: Sunday, November 23, 2014 7:08 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Low Additive Phase Noise 10 MHz Amps > > 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 <b...@hsmicrowave.com <javascript:;>> > 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:time-nuts-boun...@febo.com <javascript:;>] 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 <b...@hsmicrowave.com <javascript:;>> > 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 -- time-nuts@febo.com <javascript:;> To > unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com <javascript:;> To > unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com <javascript:;> To > unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com <javascript:;> To > unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com <javascript:;> > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.