hello Bill,

You might be interested in this one

http://www.timeok.it/wp-content/uploads/2015/08/high-performance-frequency-doublerv1-31.pdf

best,
Wilko

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

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 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 < mailto:time-nuts@lists.febo.com time-nuts@lists.febo.com>
Sent: 25 August, 2023 20:49
To: Discussion of precise time and frequency measurement < mailto:time-nuts@lists.febo.com time-nuts@lists.febo.com>
Cc: Bill Ezell < mailto:wje@quackers.net wje@quackers.net>; Bob Camp < mailto:kb8tq@n1k.org kb8tq@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 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

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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@xs4all.nl wrote:

--
Bill Ezell
I happen to know that this is the Lupin Express.

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 8/25/2023 10:39 AM, Bill Ezell via time-nuts wrote:

This only makes sense if you just happen to have a high quality VCXO in
your "junkbox".

I designed a frequency multiplier chain for the 5071A that had 5
doublers in cascade to go from 10 MHz to 320 MHz.  Here are some
take aways from that:

1. IIRC, I used Mini Circuits ASK-1 mixers where I connected the LO
   input in series with the RF input.  This works better than connecting
   them in parallel and is simpler than using a power splitter.  The "IF"
   was then the doubler output. Note:  it is not at all clear from the data
   sheet that this is even possible.  However, it turns out that these two
   inputs are floating primaries on the respective transformers in the
   ASK-1.  There is nothing unique about the ASK-1; I'm sure lots of other
   mixers would work as long as you can connect the LO and RF in series,
   which isn't always the case.
   Also, the ASK has an IF bandwidth of 600 MHz.

2. This is very important:  the input to the ASK-1 must be a pure sine
   wave.  This is not intuitively obvious at all, but if the input contains
   any harmonics of the drive frequency, it will degrade the output
   spectrum.  IIRC, I used a resonant impedance matching circuit that had a
   fairly high loaded Q to accomplish this.  It took something like +12 dBm
   of drive.

3. The output filter was not some "obvious" Butterworth low pass ladder
   filter.  Rather it was a BANDPASS filter at the output frequency, such
   as 20 MHz if the input was 10 MHz.  A bandpass is necessary to reject
   subharmonics, but the "obvious" top coupled resonator design was not
   used.  Instead, the filter consisted of series resonant tank circuits
   and parallel resonant tanks, arranged in a ladder network alternating
   between parallel resonant tanks in shunt, and series resonant tanks in
   series.  No one tank had a particularly high loaded Q, but given enough
   of them, there was a lot of selectivity.  It was all built with SMT 5%
   inductors and 1% capacitors.  Using only E12 values, combinations of
   these were used to tune each tank to the exact value needed.  After the
   first PC board came back, each and EVERY L and C was then hand tweaked
   to compensate for PC board parasitics.  There were no adjustable
   components.  The board was released to production and it just worked.  I
   never heard anything about it from the production engineers.

Perhaps this is overkill for the original poster's question, but I
thought I would share it with the group anyway.

Rick N6RK