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

[Bob Camp]

Hi

Long long ago, IC’s had not yet been invented. If you wanted a logic gate, you grabbed a bunch of transistors (or tubes ….). 
Want a flip flop? You need lots of tubes / transistors. 

A regenerative circuit was the simple answer to “let’s do this cheap and simple”. It worked with the parts they had back then.
Once dividers that worked at a really high frequency like 2.5 MHz became available (at a rational price) … you didn’t see 
many more regen dividers in new designs. 

In some cases, the “old stuff” kept on being made for quite a while. The key parameter here is “designed when” rather
than “built when”. 

Bob

> On Aug 27, 2023, at 3:58 PM, Bill Ezell <wje at quackers.net> wrote:
> 
> Ok, decided I'll try the MK-3. If it's satisfactory (and I'm sure it will be, this is all mostly just for fun), I might do up a little box with a gain block and maybe a bandpass filter in it. 
> 
> Although figuring out a regenerative multiplier would be a lot of fun. That seems to have been very popular back in the past. The HP5061 used regenerative dividers, the Sulzer 2.5A and 5A xtal stds did also. Sulzer in particular has some fascinating stuff for doing frequency division for its outputs. Complex. Regenerative dividers, regenerative multipliers, mixers, etc. There must have been a reason, right? Example, the S 5A gets 1Mhz from its primary 5Mhz by using a regenerative 4Mhz LO and mixer. No external LO source. Cute because of course the derived 1Mhz doesn't depend upon anything other than the primary freq. The spectral purity is pretty good.
> 
> BTW, my test setup is an HP 53310A using a Trimble GPS std of my own design as its ref input. The 53310A is a hugely unappreciated bit of kit, capable of measuring to theoretically e-14 with long averaging. And, calibration is trivial. Push some buttons. Unlike the awful analog fiddling needed for a 5370. And yes, I have several of those I no longer use for anything.
> 
> Bill
> 
> On 8/27/2023 2:18 PM, wkb at xs4all.nl <mailto:wkb at xs4all.nl> wrote:
>> Hi 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
>>  <mailto:time-nuts-leave at lists.febo.com>-- 
> Bill Ezell
> I happen to know that this is the Lupin Express.