> Am 11.03.23 um 18:02 schrieb Phil Hobbs:
>> On 2023-03-11 02:12, Gerhard Hoffmann wrote:
>
>>> Finding the series resonance printed on an xtal will
>>> usually work and if it doesn't, it will at least
>>> leave the phase stability of the 10 MHz alone.
>>
>> Gotcha. How deep a null do you get? I normally think of fundamental
>> crystals as having 20 ohms or so of series resistance.
>
> depends on the impedance level. Maybe 20 dB.
> 20 Ohms short in a 200 Ohm (50 Ohm* 1:4 xformer) environment.
> 1 have seen 5 Ohm fundamental crystels @ DigiKey
> and 1:9 transformers.
>
> I took what I had here. AFAIR there are 2 traps for the 5 MHz
> fundamental.
>
> cheers, Gerhard
>
Absolutely. As a fellow junkbox-builder, I get the ethos.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.nethttp://hobbs-eo.com
Reply by Gerhard Hoffmann●March 11, 20232023-03-11
Am 11.03.23 um 18:53 schrieb John Larkin:
> On Fri, 10 Mar 2023 23:14:16 +0100, Gerhard Hoffmann <dk4xp@arcor.de>
> wrote:
>
>>
>> That was just a byproduct of a 1pps signal from my GPS-synced
>> 10 MHz source. More intended to be clean than to be fast.
>>
>> < http://www.hoffmann-hochfrequenz.de/downloads/DoubDist.pdf
>
> The other way to do that would be a PLL. There are some stunning but
> affordable VCXOs and OCXOs around now with fs jitter specs.
My GPS already has a 5 MHz double oven,
MTI-260 . Without a heavy effort, I could
not improve that.
Really, it has 2 MTI-260. The other one is
a hot spare for redundancy. Built by HP
for Lucent; I got them as unused spare parts,
still factory sealed.
< http://www.mti-milliren.com/ocxo_260_ocxo.html >
BTW most of the cheap oscillators count the jitter
only from 12 KHz offset & UP. That's a telecom spec
that gives friendly numbers.
Cheers,
Gerhard
Reply by John Larkin●March 11, 20232023-03-11
On Fri, 10 Mar 2023 23:14:16 +0100, Gerhard Hoffmann <dk4xp@arcor.de>
wrote:
>Am 10.03.23 um 18:56 schrieb Phil Hobbs:
>>
>> I've been doing some simple test sources, basically just one or other
>> carefully selected LED driven by fast CMOS.� Regular hex inverter
>> packages (both 74AC04 and 74AC14) look great with resistive loads--clean
>> 250 ps -- 300 ps edges, as measured with an 11801C sampling scope with
>> SD-26 head.
>>
>> <https://electrooptical.net/www/sed/MC74AC04-14RisingEdges500ohmLoad.png>
>>
>> <https://electrooptical.net/www/sed/MC74AC04_14_FallingEdge500ohms.png>
>>
>> (There's a bit of residual inductive rise after the fast edges on the
>> resistive load tests, but we can fix that.)
>>
>> They're built dead-bug fashion with SO14 packages wired up like this:
>>
>> ������� 10nF������� +5
>> ��������� C C������ |
>> ����� *---C C-------*
>> ����� |�� C C������ |
>> ���� GND����������� |�� A
>> ��������������� *--|>o--*
>> in������������� |������ |�� 432R
>> 0---|>o---|>o---*--|>o--*---RRRR---0) To sampler
>> ��������������� |������ |���������� |
>> ��������������� *--|>o--*��������� GND
>> ��������������� |������ |
>> ��������������� *--|>o--*
>> ������������������� |
>> ������������������ GND
>>
>> With 82 pF to ground from node A, they fall completely apart--the edges
>> show an initial fast rise/fall of a volt or so, followed by a ringy mess
>> for the next 10 ns.
>>
>> <https://electrooptical.net/www/sed/MC74AC04_14_FallingEdge500ohms82pF.png>
>>
>> <https://electrooptical.net/www/sed/MC74AC04_14_RisingEdge500ohms82pF.png>
>>
>> In real life the LEDs won't be faster than 2 ns, and will be driven via
>> a resistor, of course.� However, I might well want to use a speedup cap
>> of the same order, so it's very likely to be worthwhile spending an
>> extra buck or so and using LVC1G04 gates in SC-70, with individual
>> bypass caps.
>
>> Cheers
>
>I got rise = 481 ps trise and 323 ps tfall from just 2
>74LVC1G04DCKR, 100 Ohms each, both driving the 50 Ohm input of
>an Agilent 54846B scope, 2.25 GHz BW, 156 ps trise.
>
>No need to risk the 2V samplers on 5V logic that does not
>deserve it.
>
>That was just a byproduct of a 1pps signal from my GPS-synced
>10 MHz source. More intended to be clean than to be fast.
>
>< http://www.hoffmann-hochfrequenz.de/downloads/DoubDist.pdf
The other way to do that would be a PLL. There are some stunning but
affordable VCXOs and OCXOs around now with fs jitter specs.
Reply by Gerhard Hoffmann●March 11, 20232023-03-11
Am 11.03.23 um 18:02 schrieb Phil Hobbs:
> On 2023-03-11 02:12, Gerhard Hoffmann wrote:
>> Finding the series resonance printed on an xtal will
>> usually work and if it doesn't, it will at least
>> leave the phase stability of the 10 MHz alone.
>
> Gotcha. How deep a null do you get? I normally think of fundamental
> crystals as having 20 ohms or so of series resistance.
depends on the impedance level. Maybe 20 dB.
20 Ohms short in a 200 Ohm (50 Ohm* 1:4 xformer) environment.
1 have seen 5 Ohm fundamental crystels @ DigiKey
and 1:9 transformers.
I took what I had here. AFAIR there are 2 traps for the 5 MHz
fundamental.
cheers, Gerhard
Reply by Phil Hobbs●March 11, 20232023-03-11
On 2023-03-11 02:12, Gerhard Hoffmann wrote:
> Am 11.03.23 um 01:39 schrieb Phil Hobbs:
>> On 2023-03-10 17:49, Gerhard Hoffmann wrote:
>>> Am 10.03.23 um 23:20 schrieb Phil Hobbs:
>
>>> But just take a look at the quality of these stones...
>
>> Monty Python dubbed in German is a bit surreal.
>>
>> Yessir, a very nice writeup. Out of curiosity, why did you choose
>> crystal notch filters, as opposed to an LC tuned amp?
>
> When I have a VNA on the table, the inductors are easy,
> at least known ones. The plot has been done with
> Amidon-Red inductors.
> Those from the junk box probably won't fit.
>
> Finding the series resonance printed on an xtal will
> usually work and if it doesn't, it will at least
> leave the phase stability of the 10 MHz alone.
Gotcha. How deep a null do you get? I normally think of fundamental
crystals as having 20 ohms or so of series resistance.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.nethttp://hobbs-eo.com
Reply by Jan Panteltje●March 11, 20232023-03-11
On a sunny day (Fri, 10 Mar 2023 23:14:16 +0100) it happened Gerhard Hoffmann
<dk4xp@arcor.de> wrote in <tuga3o$1svuu$1@solani.org>:
Reply by Gerhard Hoffmann●March 11, 20232023-03-11
Am 11.03.23 um 01:39 schrieb Phil Hobbs:
> On 2023-03-10 17:49, Gerhard Hoffmann wrote:
>> Am 10.03.23 um 23:20 schrieb Phil Hobbs:
>> But just take a look at the quality of these stones...
> Monty Python dubbed in German is a bit surreal.
>
> Yessir, a very nice writeup. Out of curiosity, why did you choose
> crystal notch filters, as opposed to an LC tuned amp?
When I have a VNA on the table, the inductors are easy,
at least known ones. The plot has been done with
Amidon-Red inductors.
Those from the junk box probably won't fit.
Finding the series resonance printed on an xtal will
usually work and if it doesn't, it will at least
leave the phase stability of the 10 MHz alone.
> Cheers
Gerhard
Reply by Phil Hobbs●March 10, 20232023-03-10
On 2023-03-10 17:49, Gerhard Hoffmann wrote:
> Am 10.03.23 um 23:20 schrieb Phil Hobbs:
>> On 2023-03-10 17:14, Gerhard Hoffmann wrote:
>>> Am 10.03.23 um 18:56 schrieb Phil Hobbs:
>>>>
>>>> I've been doing some simple test sources, basically just one or
>>>> other carefully selected LED driven by fast CMOS. Regular hex
>>>> inverter packages (both 74AC04 and 74AC14) look great with resistive
>>>> loads--clean 250 ps -- 300 ps edges, as measured with an 11801C
>>>> sampling scope with SD-26 head.
>>>>
>>>> <https://electrooptical.net/www/sed/MC74AC04-14RisingEdges500ohmLoad.png>
>>>>
>>>>
>>>> <https://electrooptical.net/www/sed/MC74AC04_14_FallingEdge500ohms.png>
>>>>
>>>> (There's a bit of residual inductive rise after the fast edges on
>>>> the resistive load tests, but we can fix that.)
>>>>
>>>> They're built dead-bug fashion with SO14 packages wired up like this:
>>>>
>>>> 10nF +5
>>>> C C |
>>>> *---C C-------*
>>>> | C C |
>>>> GND | A
>>>> *--|>o--*
>>>> in | | 432R
>>>> 0---|>o---|>o---*--|>o--*---RRRR---0) To sampler
>>>> | | |
>>>> *--|>o--* GND
>>>> | |
>>>> *--|>o--*
>>>> |
>>>> GND
>>>>
>
>>>
>>> I got rise = 481 ps trise and 323 ps tfall from just 2
>>> 74LVC1G04DCKR, 100 Ohms each, both driving the 50 Ohm input of
>>> an Agilent 54846B scope, 2.25 GHz BW, 156 ps trise.
>>>
>>> No need to risk the 2V samplers on 5V logic that does not
>>> deserve it.
>>>
>>> That was just a byproduct of a 1pps signal from my GPS-synced
>>> 10 MHz source. More intended to be clean than to be fast.
>>>
>>> < http://www.hoffmann-hochfrequenz.de/downloads/DoubDist.pdf >
>>> page 13 +-
>>>
>>> 74AC was OK when there was the old Fairchild around. But now
>>> there is 5V tolerant 74LVC on a contemporary process, 30 years
>>> later.
>>>
>>> Gerhard
>>>
>>
>> Seems slower though!
>
> Yes, with 4 drivers into 500 Ohms, that's easy living.
> Not so easy if you need a presentable 1pps...
>
>
> But just take a look at the quality of these stones...
> (Live of Brian)
> < https://www.youtube.com/watch?v=OVUwHv43HqM >
Monty Python dubbed in German is a bit surreal.
Yessir, a very nice writeup. Out of curiosity, why did you choose
crystal notch filters, as opposed to an LC tuned amp?
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.nethttp://hobbs-eo.com
Reply by Gerhard Hoffmann●March 10, 20232023-03-10
Am 10.03.23 um 23:20 schrieb Phil Hobbs:
> On 2023-03-10 17:14, Gerhard Hoffmann wrote:
>> Am 10.03.23 um 18:56 schrieb Phil Hobbs:
>>>
>>> I've been doing some simple test sources, basically just one or other
>>> carefully selected LED driven by fast CMOS. Regular hex inverter
>>> packages (both 74AC04 and 74AC14) look great with resistive
>>> loads--clean 250 ps -- 300 ps edges, as measured with an 11801C
>>> sampling scope with SD-26 head.
>>>
>>> <https://electrooptical.net/www/sed/MC74AC04-14RisingEdges500ohmLoad.png>
>>>
>>> <https://electrooptical.net/www/sed/MC74AC04_14_FallingEdge500ohms.png>
>>>
>>> (There's a bit of residual inductive rise after the fast edges on the
>>> resistive load tests, but we can fix that.)
>>>
>>> They're built dead-bug fashion with SO14 packages wired up like this:
>>>
>>> 10nF +5
>>> C C |
>>> *---C C-------*
>>> | C C |
>>> GND | A
>>> *--|>o--*
>>> in | | 432R
>>> 0---|>o---|>o---*--|>o--*---RRRR---0) To sampler
>>> | | |
>>> *--|>o--* GND
>>> | |
>>> *--|>o--*
>>> |
>>> GND
>>>
>>
>> I got rise = 481 ps trise and 323 ps tfall from just 2
>> 74LVC1G04DCKR, 100 Ohms each, both driving the 50 Ohm input of
>> an Agilent 54846B scope, 2.25 GHz BW, 156 ps trise.
>>
>> No need to risk the 2V samplers on 5V logic that does not
>> deserve it.
>>
>> That was just a byproduct of a 1pps signal from my GPS-synced
>> 10 MHz source. More intended to be clean than to be fast.
>>
>> < http://www.hoffmann-hochfrequenz.de/downloads/DoubDist.pdf >
>> page 13 +-
>>
>> 74AC was OK when there was the old Fairchild around. But now
>> there is 5V tolerant 74LVC on a contemporary process, 30 years
>> later.
>>
>> Gerhard
>>
>
> Seems slower though!
Yes, with 4 drivers into 500 Ohms, that's easy living.
Not so easy if you need a presentable 1pps...
But just take a look at the quality of these stones...
(Live of Brian)
< https://www.youtube.com/watch?v=OVUwHv43HqM >
> Cheers
Gerhard
Reply by Phil Hobbs●March 10, 20232023-03-10
On 2023-03-10 17:14, Gerhard Hoffmann wrote:
> Am 10.03.23 um 18:56 schrieb Phil Hobbs:
>>
>> I've been doing some simple test sources, basically just one or other
>> carefully selected LED driven by fast CMOS. Regular hex inverter
>> packages (both 74AC04 and 74AC14) look great with resistive
>> loads--clean 250 ps -- 300 ps edges, as measured with an 11801C
>> sampling scope with SD-26 head.
>>
>> <https://electrooptical.net/www/sed/MC74AC04-14RisingEdges500ohmLoad.png>
>>
>> <https://electrooptical.net/www/sed/MC74AC04_14_FallingEdge500ohms.png>
>>
>> (There's a bit of residual inductive rise after the fast edges on the
>> resistive load tests, but we can fix that.)
>>
>> They're built dead-bug fashion with SO14 packages wired up like this:
>>
>> 10nF +5
>> C C |
>> *---C C-------*
>> | C C |
>> GND | A
>> *--|>o--*
>> in | | 432R
>> 0---|>o---|>o---*--|>o--*---RRRR---0) To sampler
>> | | |
>> *--|>o--* GND
>> | |
>> *--|>o--*
>> |
>> GND
>>
>> With 82 pF to ground from node A, they fall completely apart--the
>> edges show an initial fast rise/fall of a volt or so, followed by a
>> ringy mess for the next 10 ns.
>>
>> <https://electrooptical.net/www/sed/MC74AC04_14_FallingEdge500ohms82pF.png>
>>
>>
>> <https://electrooptical.net/www/sed/MC74AC04_14_RisingEdge500ohms82pF.png>
>>
>>
>> In real life the LEDs won't be faster than 2 ns, and will be driven
>> via a resistor, of course. However, I might well want to use a
>> speedup cap of the same order, so it's very likely to be worthwhile
>> spending an extra buck or so and using LVC1G04 gates in SC-70, with
>> individual bypass caps.
>
>> Cheers
>
> I got rise = 481 ps trise and 323 ps tfall from just 2
> 74LVC1G04DCKR, 100 Ohms each, both driving the 50 Ohm input of
> an Agilent 54846B scope, 2.25 GHz BW, 156 ps trise.
>
> No need to risk the 2V samplers on 5V logic that does not
> deserve it.
>
> That was just a byproduct of a 1pps signal from my GPS-synced
> 10 MHz source. More intended to be clean than to be fast.
>
> < http://www.hoffmann-hochfrequenz.de/downloads/DoubDist.pdf > page
> 13 +-
>
> 74AC was OK when there was the old Fairchild around. But now
> there is 5V tolerant 74LVC on a contemporary process, 30 years
> later.
>
> Gerhard
>
Seems slower though!
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.nethttp://hobbs-eo.com