Anyone make PCBs with Othermill?

[Tom Swift]

John Larkin <jlarkin@highlandtechnology.com> wrote:

On Tue, 14 Jul 2015 01:32:04 GMT, Tom Swift <spam@me.com> wrote:

Then I will know what I have to work with, instead of guessing.

In a linear system, the step response includes all the information
there is. No guessing required.

Your method is the shoddiest I have ever witnessed. You are guessing when
you compare the response to another probe that someone said has such and
such a bandwidth. You did not verify the claim, and you do not have the
equipment to do so. You are guessing all the way.

The step response may have a great deal of information. But that assumes
the system is linear, the stimulus is perfect and the response is
captured perfectly.

None are true in your setup. You cannot extract the bandwidth, group
delay, reflections, phase and amplitude ripple, frequency rolloff,
attenuation, or a dozen other things you need to know if you are to use
the probe in any serious work. You do not have the capability to do so.

Your claim is highly misleading. You are using a theoretical argument
that has no relation to what you are doing. That is highly disingenuous
and has no place in professional organization.

Instead of acknowledging there is a better source for a microwave
resistor for a resistive probe, you will ignore it and continue pushing
the Caddock as your solution. Just because that's the way you are.

I don't care. I am beyond wasting my time. Those who need to know
anything about what you say can easily find the solutions elsewhere.

And I highly recommend they do so.

 

[John Larkin]

On Tue, 14 Jul 2015 01:32:04 GMT, Tom Swift <spam@me.com> wrote:

John Larkin <jlarkin@highlandtechnology.com> wrote:

On Mon, 13 Jul 2015 23:08:05 GMT, Tom Swift <spam@me.com> wrote:

How do you know? What do you have to measure it?

A Tek 11801 TDR/Sampling scope, around 30 ps net pulser+scope rise
time. And Agilent specs the probe for 6 GHz.

Sounds kind of a loose way to define the frequency response.

Then do it your way.

No problem. That's what I was planning on doing.

Then I will know what I have to work with, instead of guessing.

In a linear system, the step response includes all the information
there is. No guessing required.


--

John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Tom Swift]

John Larkin <jlarkin@highlandtechnology.com> wrote:

On Mon, 13 Jul 2015 23:08:05 GMT, Tom Swift <spam@me.com> wrote:

How do you know? What do you have to measure it?

A Tek 11801 TDR/Sampling scope, around 30 ps net pulser+scope rise
time. And Agilent specs the probe for 6 GHz.

Sounds kind of a loose way to define the frequency response.

Then do it your way.

No problem. That's what I was planning on doing.

Then I will know what I have to work with, instead of guessing.

 

[Phil Hobbs]

Your claim is highly misleading. You are using a theoretical argument
that has no relation to what you are doing. That is highly disingenuous
and has no place in professional organization.

Yo, dude, dial it back a bit. You may be an RF god yourself, or at least somebody who knows what one looks like, but most of the FET probes in the universe are used with scopes.

A scope lives and dies by its step response, so there's nothing shoddy whatsoever abot centering on that. In fact, a good step response with low edge artifacts and near-zero tilt is very hard to get--it requires flatness and phase linearity over multiple decades of frequency.

Saying that a perfectly factual statement is "disingenuous" and not "professional" and trying to smear a fine outfit that you obviously know little about--well, that suggests that you'd lost your temper, at very least, or were maybe drunk. So do dial it back.

Cheers

Phil Hobbs

 

[John Larkin]

On Tue, 14 Jul 2015 06:15:54 GMT, Tom Swift <spam@me.com> wrote:

John Larkin <jlarkin@highlandtechnology.com> wrote:

On Tue, 14 Jul 2015 01:32:04 GMT, Tom Swift <spam@me.com> wrote:

Then I will know what I have to work with, instead of guessing.

In a linear system, the step response includes all the information
there is. No guessing required.

Your method is the shoddiest I have ever witnessed.

I assume you have spent your entire life in an especially severe
monastery, that uses no Microsoft products.


You are guessing when

you compare the response to another probe that someone said has such and
such a bandwidth. You did not verify the claim, and you do not have the
equipment to do so. You are guessing all the way.

The step response of a probe isn't a guess. TDR can also be used to
characterize a probe's input impedance. My personal limitation is that
my TDR gear has roughly 28 ps net risetime, so my bandwidth limit is
around 12 GHz.

The step response may have a great deal of information. But that assumes
the system is linear, the stimulus is perfect and the response is
captured perfectly.

What's the amplitude of the test signal from your VNA? How will you
use the VNA to characterize probe linearity?

None are true in your setup. You cannot extract the bandwidth, group
delay, reflections, phase and amplitude ripple, frequency rolloff,
attenuation, or a dozen other things you need to know if you are to use
the probe in any serious work. You do not have the capability to do so.

The derivative of the step response is the impulse response. That can
be FFTd to complex frequency response. Any reflections will be
immediately visible in a step response. How does your VNA characterize
reflections and locations? The usual way will be to do reverse FFT
things to derive the step and impulse responses, which a time-domain
measurement already has.

If I have a fast system with a reflective abberation, I can slide my
finger or a pencil point along the signal path and zero in on the
connector or via or whatever is reflecting, in real time. That's
really cool.

A good probe has a clean gaussian step response and no nasty ringing
or reflections. Bandwidth is then about 0.35/Tr. Tek published a book
on probe design, part of their Circuit Concept Series. Do you have
that one?

Your claim is highly misleading.

What claim? Misleading how?

You are using a theoretical argument

that has no relation to what you are doing. That is highly disingenuous
and has no place in professional organization.

I've done GHz probing up to kilovolts, with Caddocks and surface-mount
parts. We build passive and active probes into PCBs to snoop fast
stuff like differential PciExpress. The stuff that we do is real, not
theoretical, and people buy it. We work mostly in the time domain,
which is just as valid as working in frequency domain, and better in
some respects. Time and frequency domains are just an FFT apart.

Instead of acknowledging there is a better source for a microwave
resistor for a resistive probe, you will ignore it and continue pushing
the Caddock as your solution. Just because that's the way you are.

Why are you getting so personal and insulting, when we have an
interesting topic that we could discuss? I never insulted you, I
shared some stuff that we do. If you disgree with what I've said, say
why, technically.

The Caddock is a cool way to quickly make a 6 GHz probe, in minutes,
that tolerates kilovolts, for a few dollars (or less, because they are
good about samples.) Sure, if you want to lay out a board and use
surface mount resistors to go faster, do that.

Above about 10 GHz, the skin loss in the cabling will get serious, and
will need to be equalized out in hardware or software. A probe with
hardline cabling can be awkward; trust me on that one.

The Tek book is a good start there... lots or radical equalization.
But I'd go software these days.

I don't care. I am beyond wasting my time. Those who need to know
anything about what you say can easily find the solutions elsewhere.

And I highly recommend they do so.

Let us know how your 30 GHz probe works out.



--

John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[John Larkin]

On Tue, 14 Jul 2015 03:41:51 -0700 (PDT), Phil Hobbs
<pcdhobbs@gmail.com> wrote:

Your claim is highly misleading. You are using a theoretical argument
that has no relation to what you are doing. That is highly disingenuous
and has no place in professional organization.

Yo, dude, dial it back a bit. You may be an RF god yourself, or at least somebody who knows what one looks like, but most of the FET probes in the universe are used with scopes.

The acid test, and a main application, is eye diagrams from
differential signals. Some of the diff probes are designed to be
soldered into the circuit to be snooped. Good replacement market.


--

John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Phil Hobbs]

On 07/14/2015 11:59 AM, John Larkin wrote:

On Tue, 14 Jul 2015 03:41:51 -0700 (PDT), Phil Hobbs
pcdhobbs@gmail.com> wrote:

Your claim is highly misleading. You are using a theoretical
argument that has no relation to what you are doing. That is
highly disingenuous and has no place in professional
organization.

Yo, dude, dial it back a bit. You may be an RF god yourself, or at
least somebody who knows what one looks like, but most of the FET
probes in the universe are used with scopes.

The acid test, and a main application, is eye diagrams from
differential signals. Some of the diff probes are designed to be
soldered into the circuit to be snooped. Good replacement market.

Seems like if you did it enough, it would be cheaper to build your own.
Back in the 80s people were building samplers based on electro-optic
crystals and picosecond lasers. The bad news was that the circuit had
to be synched to the laser rep rate, not the other way round.

Cheers

Phil Hobbs



--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[John Larkin]

On Tue, 14 Jul 2015 15:00:35 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 07/14/2015 11:59 AM, John Larkin wrote:
On Tue, 14 Jul 2015 03:41:51 -0700 (PDT), Phil Hobbs
pcdhobbs@gmail.com> wrote:

Your claim is highly misleading. You are using a theoretical
argument that has no relation to what you are doing. That is
highly disingenuous and has no place in professional
organization.

Yo, dude, dial it back a bit. You may be an RF god yourself, or at
least somebody who knows what one looks like, but most of the FET
probes in the universe are used with scopes.

The acid test, and a main application, is eye diagrams from
differential signals. Some of the diff probes are designed to be
soldered into the circuit to be snooped. Good replacement market.

Seems like if you did it enough, it would be cheaper to build your own.
Back in the 80s people were building samplers based on electro-optic
crystals and picosecond lasers. The bad news was that the circuit had
to be synched to the laser rep rate, not the other way round.

Cheers

Phil Hobbs

Right, you can't trigger a laser with tolerable jitter.

Hypres made a superconductive sampling scope that needed a jug of
liquid helium. That didn't last long.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Phil Hobbs]

On 07/14/2015 03:37 PM, John Larkin wrote:

On Tue, 14 Jul 2015 15:00:35 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 07/14/2015 11:59 AM, John Larkin wrote:
On Tue, 14 Jul 2015 03:41:51 -0700 (PDT), Phil Hobbs
pcdhobbs@gmail.com> wrote:

Your claim is highly misleading. You are using a theoretical
argument that has no relation to what you are doing. That is
highly disingenuous and has no place in professional
organization.

Yo, dude, dial it back a bit. You may be an RF god yourself, or at
least somebody who knows what one looks like, but most of the FET
probes in the universe are used with scopes.

The acid test, and a main application, is eye diagrams from
differential signals. Some of the diff probes are designed to be
soldered into the circuit to be snooped. Good replacement market.

Seems like if you did it enough, it would be cheaper to build your own.
Back in the 80s people were building samplers based on electro-optic
crystals and picosecond lasers. The bad news was that the circuit had
to be synched to the laser rep rate, not the other way round.

Cheers

Phil Hobbs

Right, you can't trigger a laser with tolerable jitter.

Hypres made a superconductive sampling scope that needed a jug of
liquid helium. That didn't last long.


I knew Sadeg Faris slightly--he was a FOAF. That was a pretty cool gizmo.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[John Larkin]

On Tue, 14 Jul 2015 15:44:20 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 07/14/2015 03:37 PM, John Larkin wrote:
On Tue, 14 Jul 2015 15:00:35 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 07/14/2015 11:59 AM, John Larkin wrote:
On Tue, 14 Jul 2015 03:41:51 -0700 (PDT), Phil Hobbs
pcdhobbs@gmail.com> wrote:

Your claim is highly misleading. You are using a theoretical
argument that has no relation to what you are doing. That is
highly disingenuous and has no place in professional
organization.

Yo, dude, dial it back a bit. You may be an RF god yourself, or at
least somebody who knows what one looks like, but most of the FET
probes in the universe are used with scopes.

The acid test, and a main application, is eye diagrams from
differential signals. Some of the diff probes are designed to be
soldered into the circuit to be snooped. Good replacement market.

Seems like if you did it enough, it would be cheaper to build your own.
Back in the 80s people were building samplers based on electro-optic
crystals and picosecond lasers. The bad news was that the circuit had
to be synched to the laser rep rate, not the other way round.

Cheers

Phil Hobbs

Right, you can't trigger a laser with tolerable jitter.

Hypres made a superconductive sampling scope that needed a jug of
liquid helium. That didn't last long.


I knew Sadeg Faris slightly--he was a FOAF. That was a pretty cool gizmo.

Cheers

Phil Hobbs

I think it was a "slideback sampler" like my tunnel-diode college
project, an equivalent-time sampler with a 1-bit comparator.

They managed to spray helium onto the sampler substrate that was
really, really close to the input SMA.

They're still around:

http://www.hypres.com/

Shock line samplers are more practical. Research samplers have got to
300 GHz or something crazy like that, but I think the fastest
commercial scope is around 100 GHz. At some point, connectors and
cables just don't work.



--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com