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Discussion of precise time and frequency measurement

hydrogen rich environment and oscillators

glen english LIST

Tue, Jan 17, 2023 8:48 AM

Thanks Bob and Rick for the time taken to write up the info.

also, undersampling the output to an audio amplifier, I can HEAR this
noise, a bit bursty. When I undersample a harmonic of the HP oscillators
I have - I do not hear said noise ( my 10811, or my E1948.) . ....I've
never really paid much attention this close in (1 Hz <= 10 Hz) but I am
building a much better high performance ADC clock reference than I
currently have.

I have some newer crystals arriving this week from a company in .CZ ,
and I will try a few different transistors and measure also at 100Hz.
Oh ESR as far as I can measure is about 120 ohms they are cheap and seem
to have a bit of non-monotonicity when bending them.. New crystals
coming are 3rdOT and spec at 40 ohms.

I will report back.

-glen

On 17/01/2023 12:12 pm, Richard Karlquist wrote:

Generally speaking, the 1/f noise at, say 10 Hz, for a crystal
oscillator is determined

entirely by the intrinsic noise of the crys

Thanks Bob and Rick for the time taken to write up the info. also, undersampling the output to an audio amplifier, I can HEAR this noise, a bit bursty. When I undersample a harmonic of the HP oscillators I have - I do not hear said noise ( my 10811, or my E1948.) . ....I've never really paid much attention this close in (1 Hz <= 10 Hz) but I am building a much better high performance ADC clock reference than I currently have. I have some newer crystals arriving this week from a company in .CZ , and I will try a few different transistors and measure also at 100Hz. Oh ESR as far as I can measure is about 120 ohms they are cheap and seem to have a bit of non-monotonicity when bending them.. New crystals coming are 3rdOT and spec at 40 ohms. I will report back. -glen On 17/01/2023 12:12 pm, Richard Karlquist wrote: > > Generally speaking, the 1/f noise at, say 10 Hz, for a crystal > oscillator is determined > > entirely by the intrinsic noise of the crys >

Magnus Danielson

Tue, Jan 17, 2023 9:24 AM

Hi Rick!

On 2023-01-17 02:12, Richard Karlquist via time-nuts wrote:

Generally speaking, the 1/f noise at, say 10 Hz, for a crystal oscillator is determined entirely by the intrinsic noise of the crystal. It's really hard to screw up an oscillator circuit so badly that it actually contributes anything to the oscillator 1/f noise.

For instance, I'm sure we will all agree that the HP 10811 is a pretty decent oscillator.

FYI, essentially the same crystal is used in the E1938A that I designed. Those two oscillators have ENTIRELY different circuits. Yet both achieve the same close in phase noise as what I measured for the intrinsic noise of the crystal. By the way, the HP 10811 uses a selected 2N5179 transistor. But is NOT SELECTED FOR 1/f NOISE. Instead it is selected for good gain at high DC collector current, because the HP engineer who designed it had trouble with the oscillator starting up correctly, in conjunction with the ALC circuit.

If you use the same output circuit for your oscillator as the 10811, you will also have no oscillator transistor contribution to far out phase noise. This is all very well documented if you want to read the details.

In a previous life, I designed many many 5th overtone oscillators. Your crystal like the Croven ones I used in those days is not of the same caliber as the 10811 crystal, so therefore it is even more unlikely that the transistor you choose is going to make any difference. I always locked my 5th OT crystals to something like a 10544 oscillator to clean them up close in using PLL synthesizers. The 10811 hadn't been invented yet.

Good point raised here! The clean-up lock to solve close-in noise for
higher frequencies I think some may not have considered. As one has an
oscillator at higher frequency, the same loaded Q of the resonator will
mean higher cut-over corner for the noise. To keep 10 Hz or so to be
quiet, lock the high frequency oscillator to a lower frequency
oscillator with a narrower noise, using PLL. For odd frequencies
synthesis may be needed also. The PLL will high-pass filter the locked
oscillators close-in noise while lowpass the reference oscillators
close-in, so a nice cross-over.

I think that is a much more reasonable approach than trying to cram
everything into one signle oscillator.

I hope this gets you back on the right track.

Very good read. Thanks for sharing!

Cheers,
Magnus

Rick Karlquist
N6RK

On 2023-01-16 14:26, glen english LIST via time-nuts wrote:

Hi

I am embarking on building up a block - a common collector Butler oscillator with an overtone crystal at 98.304 MHz

on on FR4 , I've used the Philips NPN type BFS17.

The results <=10 Hz phase noise were quite disappointing. (-69 @ 98 MHz)

Does anyone have any good suggestions. Maybe something slower (larger) like a 2N5179 (or its SMT counterpart MMBT5179) will be better.

regards

glen

On 13/12/2022 11:14 am, Lux, Jim via time-nuts wrote:

On 12/12/22 2:43 PM, Alex Pumm

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Hi Rick! On 2023-01-17 02:12, Richard Karlquist via time-nuts wrote: > Generally speaking, the 1/f noise at, say 10 Hz, for a crystal oscillator is determined entirely by the intrinsic noise of the crystal. It's really hard to screw up an oscillator circuit so badly that it actually contributes anything to the oscillator 1/f noise. > > For instance, I'm sure we will all agree that the HP 10811 is a pretty decent oscillator. > > FYI, essentially the same crystal is used in the E1938A that I designed. Those two oscillators have ENTIRELY different circuits. Yet both achieve the same close in phase noise as what I measured for the intrinsic noise of the crystal. By the way, the HP 10811 uses a selected 2N5179 transistor. But is NOT SELECTED FOR 1/f NOISE. Instead it is selected for good gain at high DC collector current, because the HP engineer who designed it had trouble with the oscillator starting up correctly, in conjunction with the ALC circuit. > > If you use the same output circuit for your oscillator as the 10811, you will also have no oscillator transistor contribution to far out phase noise. This is all very well documented if you want to read the details. > > In a previous life, I designed many many 5th overtone oscillators. Your crystal like the Croven ones I used in those days is not of the same caliber as the 10811 crystal, so therefore it is even more unlikely that the transistor you choose is going to make any difference. I always locked my 5th OT crystals to something like a 10544 oscillator to clean them up close in using PLL synthesizers. The 10811 hadn't been invented yet. Good point raised here! The clean-up lock to solve close-in noise for higher frequencies I think some may not have considered. As one has an oscillator at higher frequency, the same loaded Q of the resonator will mean higher cut-over corner for the noise. To keep 10 Hz or so to be quiet, lock the high frequency oscillator to a lower frequency oscillator with a narrower noise, using PLL. For odd frequencies synthesis may be needed also. The PLL will high-pass filter the locked oscillators close-in noise while lowpass the reference oscillators close-in, so a nice cross-over. I think that is a much more reasonable approach than trying to cram everything into one signle oscillator. > I hope this gets you back on the right track. Very good read. Thanks for sharing! Cheers, Magnus > > --- > Rick Karlquist > N6RK > > On 2023-01-16 14:26, glen english LIST via time-nuts wrote: > >> Hi >> >> I am embarking on building up a block - a common collector Butler oscillator with an overtone crystal at 98.304 MHz >> >> on on FR4 , I've used the Philips NPN type BFS17. >> >> The results <=10 Hz phase noise were quite disappointing. (-69 @ 98 MHz) >> >> Does anyone have any good suggestions. Maybe something slower (larger) like a 2N5179 (or its SMT counterpart MMBT5179) will be better. >> >> regards >> >> glen >> >> On 13/12/2022 11:14 am, Lux, Jim via time-nuts wrote: >> >>> On 12/12/22 2:43 PM, Alex Pumm >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe send an email to time-nuts-leave@lists.febo.com > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

glen english LIST

Tue, Jan 17, 2023 7:43 PM

Really interesting discussion.

The reasion for my 98.304 meg synthesiser reference, it allows me to run
the phase det at 98 megs principally to improve 5kHz-100kHz region. PLL
BW ~ 90kHz. VCO with ADF4356 running at x64 (6 gigs) (393 MHz output) .
It's quite good.

However ! performance limit <= 100Hz is very much the reference.

So- would need to lock that 98 meg 3OT crystal so something like a 6.144
. Wonder how effective an harmonic injection lock here is compared to a
PLL for the 0.1Hz to 100 Hz region. I will need to understand this
better and do some revision and reading.....

Or start with a 6.144 or 12.88 and multiply up to 98 megs and use that,
with any multiplier evils.

I note Rick when I re read the HP papers on the 10811 they had to start
at -55 deg C..... funny.

(I have considered 98 >>doubler >> 196>>doubler >> 393 and no synth ,
but the synth provides me some get out of jail aliasing options) .

I have a ceramic dielectric resonator at 393 MHz synth output to kill
off wideband > +10 MHz spurs (which are around -85dBc) . The $5 fix was
very effective. (Er=90, about 20mm long ) .

-glen

On 17/01/2023 8:24 pm, Magnus Danielson via time-nuts wrote:

Hi Rick!

On 2023-01-17 02:12, Richard Karlquist via time-nuts wrote:

Generally speaking, the 1/f noise at, say 10 Hz, for a crystal
oscillator is determined entirely by the intrinsic noise of the
crystal. It's really hard to screw up an oscillator circuit so badly
that it actually contributes anything to the oscillator 1/f noise.

For instance, I'm sure we will all agree that the HP 10811 is a
pretty decent oscillator.

FYI, essentially the same crystal is used in the E1938A that I
designed. Those two oscillators have ENTIRELY different circuits.
Yet both achieve the same close in phase noise as what I measured for
the intrinsic noise of the crystal. By the way, the HP 10811 uses a
selected 2N5179 transistor. But is NOT SELECTED FOR 1/f NOISE.
Instead it is selected for good gain at high DC collector current,
because the HP engineer who designed it had trouble with the
oscillator starting up correctly, in conjunction with the ALC circuit.

If you use the same output circuit for your oscillator as the 10811,
you will also have no oscillator transistor contribution to far out
phase noise. This is all very well documented if you want to read the
details.

In a previous life, I designed many many 5th overtone oscillators.
Your crystal like the Croven ones I used in those days is not of the
same caliber as the 10811 crystal, so therefore it is even more
unlikely that the transistor you choose is going to make any
difference. I always locked my 5th OT crystals to something like a
10544 oscillator to clean them up close in using PLL synthesizers.
The 10811 hadn't been invented yet.

Good point raised here! The clean-up lock to solve close-in noise for
higher frequencies I think some may not have considered. As one has an
oscillator at higher frequency, the same loaded Q of the resonator
will mean higher cut-over corner for the noise. To keep 10 Hz or so to
be quiet, lock the high frequency oscillator to a lower frequency
oscillator with a narrower noise, using PLL. For odd frequencies
synthesis may be needed also. The PLL will high-pass filter the locked
oscillators close-in noise while lowpass the reference oscillators
close-in, so a nice cross-over.

I think that is a much more reasonable approach than trying to cram
everything into one signle oscillator.

I hope this gets you back on the right track.

Very good read. Thanks for sharing!

Cheers,
Magnus

Rick Karlquist
N6RK

On 2023-01-16 14:26, glen english LIST via time-nuts wrote:

Hi

I am embarking on building up a block - a common collector Butler
oscillator with an overtone crystal at 98.304 MHz

on on FR4 , I've used the Philips NPN type BFS17.

The results <=10 Hz phase noise were quite disappointing. (-69 @ 98
MHz)

Does anyone have any good suggestions. Maybe something slower
(larger) like a 2N5179 (or its SMT counterpart MMBT5179) will be
better.

regards

glen

On 13/12/2022 11:14 am, Lux, Jim via time-nuts wrote:

On 12/12/22 2:43 PM, Alex Pumm

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Really interesting discussion. The reasion for my 98.304 meg synthesiser reference, it allows me to run the phase det at 98 megs principally to improve 5kHz-100kHz region. PLL BW ~ 90kHz. VCO with ADF4356 running at x64 (6 gigs) (393 MHz output) . It's quite good. However ! performance limit <= 100Hz is very much the reference. So- would need to lock that 98 meg 3OT crystal so something like a 6.144 . Wonder how effective an harmonic injection lock here is compared to a PLL for the 0.1Hz to 100 Hz region. I will need to understand this better and do some revision and reading..... Or start with a 6.144 or 12.88 and multiply up to 98 megs and use that, with any multiplier evils. I note Rick when I re read the HP papers on the 10811 they had to start at -55 deg C..... funny. (I have considered 98 >>doubler >> 196>>doubler >> 393 and no synth , but the synth provides me some get out of jail aliasing options) . I have a ceramic dielectric resonator at 393 MHz synth output to kill off wideband > +10 MHz spurs (which are around -85dBc) . The $5 fix was very effective. (Er=90, about 20mm long ) . -glen On 17/01/2023 8:24 pm, Magnus Danielson via time-nuts wrote: > Hi Rick! > > On 2023-01-17 02:12, Richard Karlquist via time-nuts wrote: >> Generally speaking, the 1/f noise at, say 10 Hz, for a crystal >> oscillator is determined entirely by the intrinsic noise of the >> crystal. It's really hard to screw up an oscillator circuit so badly >> that it actually contributes anything to the oscillator 1/f noise. >> >> For instance, I'm sure we will all agree that the HP 10811 is a >> pretty decent oscillator. >> >> FYI, essentially the same crystal is used in the E1938A that I >> designed. Those two oscillators have ENTIRELY different circuits. >> Yet both achieve the same close in phase noise as what I measured for >> the intrinsic noise of the crystal. By the way, the HP 10811 uses a >> selected 2N5179 transistor. But is NOT SELECTED FOR 1/f NOISE. >> Instead it is selected for good gain at high DC collector current, >> because the HP engineer who designed it had trouble with the >> oscillator starting up correctly, in conjunction with the ALC circuit. >> >> If you use the same output circuit for your oscillator as the 10811, >> you will also have no oscillator transistor contribution to far out >> phase noise. This is all very well documented if you want to read the >> details. >> >> In a previous life, I designed many many 5th overtone oscillators. >> Your crystal like the Croven ones I used in those days is not of the >> same caliber as the 10811 crystal, so therefore it is even more >> unlikely that the transistor you choose is going to make any >> difference. I always locked my 5th OT crystals to something like a >> 10544 oscillator to clean them up close in using PLL synthesizers. >> The 10811 hadn't been invented yet. > > Good point raised here! The clean-up lock to solve close-in noise for > higher frequencies I think some may not have considered. As one has an > oscillator at higher frequency, the same loaded Q of the resonator > will mean higher cut-over corner for the noise. To keep 10 Hz or so to > be quiet, lock the high frequency oscillator to a lower frequency > oscillator with a narrower noise, using PLL. For odd frequencies > synthesis may be needed also. The PLL will high-pass filter the locked > oscillators close-in noise while lowpass the reference oscillators > close-in, so a nice cross-over. > > I think that is a much more reasonable approach than trying to cram > everything into one signle oscillator. > >> I hope this gets you back on the right track. > > Very good read. Thanks for sharing! > > Cheers, > Magnus > >> >> --- >> Rick Karlquist >> N6RK >> >> On 2023-01-16 14:26, glen english LIST via time-nuts wrote: >> >>> Hi >>> >>> I am embarking on building up a block - a common collector Butler >>> oscillator with an overtone crystal at 98.304 MHz >>> >>> on on FR4 , I've used the Philips NPN type BFS17. >>> >>> The results <=10 Hz phase noise were quite disappointing. (-69 @ 98 >>> MHz) >>> >>> Does anyone have any good suggestions. Maybe something slower >>> (larger) like a 2N5179 (or its SMT counterpart MMBT5179) will be >>> better. >>> >>> regards >>> >>> glen >>> >>> On 13/12/2022 11:14 am, Lux, Jim via time-nuts wrote: >>> >>>> On 12/12/22 2:43 PM, Alex Pumm >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com >>> To unsubscribe send an email to time-nuts-leave@lists.febo.com >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe send an email to time-nuts-leave@lists.febo.com > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com