[time-nuts] Re: Working on a low-phase-noise frequency multiplier

[Bob Camp]

Hi

Assuming the objective is simply to get a signal into the test gear, the sub-harmonics
and harmonics probably don’t matter. You just need an “on frequency” carrier to look at. 

Phase noise and ADEV wise, the diode doublers are hard to beat. If you are looking for 
-180 dbc / Hz sort of phase noise, your target sources aren’t going to deliver that anyway :). 
(that includes the one I may have designed). 

Any form of narrowband filtering is going to add temperature dependent delay into the 
mix. Depending on the application, that may or may not be a big deal.

Bob

> On Aug 27, 2023, at 8:43 AM, <wkb at xs4all.nl> <wkb at xs4all.nl> wrote:
> 
> Bob, Bill,
>  
> Just to satisfy my, and maybe part of your, curiosity I ran some experiments. Coincidence has it that I own a Minicircuits MK-3 doubler. It was part of the original Efratom MRK setup, it sat between the FRK Rb and the MGPS module.
>  
> Anyway, on the SA it looks like in the attached screenshots.
>  
> Legenda:
> - Plain-Efra-FRK is the spectrum obtained directly from the FRK-HLN
> - The two Efra-MCL-MK-3-doubler-* are as the name implies the spectra from the MCL MK-3
> - The Efra-builtin-doubler-V1.BMP is based on the design at http://www.timeok.it/wp-content/uploads/2015/08/high-performance-frequency-doublerv1-31.pdf  V1 refers to the first prototype version of the PCB designed by Dave PA5DOF. 
>    ( 'builtin' references the fact that it is  builtin my Efratom rack). It might be worth noting that that the spectrum was obtained from one of the Efratom MBF distribution amp outputs, so not directly from the doubler. 
>   The spectrum It is not as clean as shown on the referenced web page.
>  
> Dave's and my joint rabbit hole led to the design of a V2 PCB to correct some minor layout goofups in V1. Which, as Murphy dictates, has fresh anomalies with the 5 MHz input signal 'punching through'. Reason is  as of yet under investigation. This is screenshot "v2-doubler-nieuwe-trafo-en-L4-C.bmp. "No Good" ☹
>  
> I do not own something which can measure phase noise (i.e. the HP 8595E SA really does not qualify) so I cannot tell you how things compare on the PN front.
>  
> Best,
> Wilko
>  
> -----Original Message-----
> From: Bob Camp via time-nuts <time-nuts at lists.febo.com <mailto:time-nuts at lists.febo.com>> 
> Sent: 25 August, 2023 20:49
> To: Discussion of precise time and frequency measurement <time-nuts at lists.febo.com <mailto:time-nuts at lists.febo.com>>
> Cc: Bill Ezell <wje at quackers.net <mailto:wje at quackers.net>>; Bob Camp <kb8tq at n1k.org <mailto:kb8tq at n1k.org>>
> Subject: [time-nuts] Re: Working on a low-phase-noise frequency multiplier
>  
> Hi
>  
> You will do better with a diode bridge style doubler on the 5 MHz devices. Mini circuits among others makes them and they may show up on eBay.  The MK-3 is fine if you need connectors. The RK-3+ 
>  
> https://www.minicircuits.com/WebStore/dashboard.html?model=RK-3%2B
>  
> combined with a cheap ( = JLPCB) board would be my choice. If you do some bandpass filtering, it will also work as a 4X device. If the target it simply the TinyPFA, you may not need any filtering …. (narrow band may have some advantages …).
>  
> Bob
>  
>  
>  
> > On Aug 25, 2023, at 1:39 PM, Bill Ezell via time-nuts <time-nuts at lists.febo.com <mailto:time-nuts at lists.febo.com>> wrote:
> > 
> > I have some old frequency standards that provide 1, 2.5, or 5 Mhz outputs, not great for comparing against modern 10Mhz standards.
> > 
> > I could do a divider, pretty easy, but only useful for doing analysis. Better to have 10Mhz output.
> > 
> > So, I'm thinking a multiplier. There are many versions, from simple diode ones and up.
> > 
> > It seems that doing an integer-N PLL with a VCXO would be the way to go. The capture range can be quite narrow since the input will be something that's within a 1 Hz range and a long loop constant might be good. Plus, with a good-quality VCXO, I would expect the noise figure to match the VCXO's pretty closely.
> > 
> > Any comments before I wander off into la-la land? BTW, Analog Devices has some good PLL design tools.
> > 
> > So, what sparked this? I bought one of the Sulters that was mentioned a while back, 2.5Mcycles (gotta be historically accurate). I also have an equally-ancient Vectron double-oven std that, last I tested it, was down in the e-11 or better range. I also got a TinyVNA which is now a TinyPFA, and it can only deal with equal freq inputs. I want to also compare that against my HP 5370 and 53310. You can see the slippery slope.
> > 
> > Thanks, Bill
> > 
> > --
> > Bill Ezell
> > I happen to know that this is the Lupin Express.
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>  
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com <mailto:time-nuts at lists.febo.com> To unsubscribe send an email to time-nuts-leave at lists.febo.com <mailto:time-nuts-leave at lists.febo.com><Plain-Efra-FRK.bmp><Efra-MCL-MK-3-doubler-15MHz.bmp><Efra-MCL-MK-3-doubler-20MHz.bmp><Efra-builtin-doubler-V1.bmp><v2-doubler-nieuwe-trafo-en-L4-C.bmp>