7603 CRT max possible bandwidth?


 

Hi,
if a 7603 CRT (the "bigger" CRT for those who don't recall) were moved
to a different mainframe, what would the maximum possible vertical and
horizontal bandwidths it could handle?

With all scopes, those two are usually different. Is this due to how
the CRT is built or is the CRT generally equal in all directions and
it's due to the supporting electronics?

Cheers,
D.


 

The horizontal bandwidth is usually limited by the horizontal CRT
amplifier which is designed for linearity at the expense of bandwidth.

CRT bandwidth is ultimately limited by the deflection plate design.
CRTs faster than the 760x have distributed vertical deflection plates
to support bandwidths above 100 MHz. The 7104 CRT has distributed
horizontal deflection plates to support a 250 MHz horizontal bandwidth
with a horizontal CRT amplifier that looks more like the vertical CRT
amplifier in a slower oscilloscope.

So the 760x CRT should support at least 100 MHz in either direction
and the difference in horizontal and vertical bandwidth is mostly
because of the CRT amplifiers. You could always test it by turning
the CRT 90 degrees and hooking it up.

The 760x CRT bandwidth ultimately depends on the lumped nature of the
deflection plates. You could drive them with a lower impedance
amplifier up to the point where the series inductance becomes a
limiting factor.

On Fri, 12 Jul 2013 13:41:22 +0200, "cheater00 ."
<cheater00@gmail.com> wrote:

Hi,
if a 7603 CRT (the "bigger" CRT for those who don't recall) were moved
to a different mainframe, what would the maximum possible vertical and
horizontal bandwidths it could handle?

With all scopes, those two are usually different. Is this due to how
the CRT is built or is the CRT generally equal in all directions and
it's due to the supporting electronics?

Cheers,
D.


 

David,

On Fri, Jul 12, 2013 at 3:03 PM, David <davidwhess@gmail.com> wrote:
The horizontal bandwidth is usually limited by the horizontal CRT
amplifier which is designed for linearity at the expense of bandwidth.

CRT bandwidth is ultimately limited by the deflection plate design.
CRTs faster than the 760x have distributed vertical deflection plates
to support bandwidths above 100 MHz. The 7104 CRT has distributed
horizontal deflection plates to support a 250 MHz horizontal bandwidth
with a horizontal CRT amplifier that looks more like the vertical CRT
amplifier in a slower oscilloscope.

So the 760x CRT should support at least 100 MHz in either direction
and the difference in horizontal and vertical bandwidth is mostly
because of the CRT amplifiers. You could always test it by turning
the CRT 90 degrees and hooking it up.

The 760x CRT bandwidth ultimately depends on the lumped nature of the
deflection plates. You could drive them with a lower impedance
amplifier up to the point where the series inductance becomes a
limiting factor.
Interesting. How far up do you think this will go in terms of vertical
deflection? 200MHz? 400 MHz? What's the fastest oscilloscope with this
type of deflection plate arrangement?

I wonder how come no higher-speed CRTs of this size have been
produced. I understand it's easier to precisely deflect by smaller
amounts, but I must wonder if that's such a big hurdle.

Cheers,
Damian


 

On Fri, 12 Jul 2013 20:21:10 +0200, "cheater00 ."
<cheater00@gmail.com> wrote:

David,

On Fri, Jul 12, 2013 at 3:03 PM, David <davidwhess@gmail.com> wrote:
The horizontal bandwidth is usually limited by the horizontal CRT
amplifier which is designed for linearity at the expense of bandwidth.

CRT bandwidth is ultimately limited by the deflection plate design.
CRTs faster than the 760x have distributed vertical deflection plates
to support bandwidths above 100 MHz. The 7104 CRT has distributed
horizontal deflection plates to support a 250 MHz horizontal bandwidth
with a horizontal CRT amplifier that looks more like the vertical CRT
amplifier in a slower oscilloscope.

So the 760x CRT should support at least 100 MHz in either direction
and the difference in horizontal and vertical bandwidth is mostly
because of the CRT amplifiers. You could always test it by turning
the CRT 90 degrees and hooking it up.

The 760x CRT bandwidth ultimately depends on the lumped nature of the
deflection plates. You could drive them with a lower impedance
amplifier up to the point where the series inductance becomes a
limiting factor.
Interesting. How far up do you think this will go in terms of vertical
deflection? 200MHz? 400 MHz? What's the fastest oscilloscope with this
type of deflection plate arrangement?
Tektronix used distributed deflection plates in the 475 and 7704 which
are 200 MHz. My guess is that the pole formed by the deflection plate
series inductance would limit you to about 100 MHz but that you could
compensate it out at the expense of difficult transient response
calibration to get to at least 200 MHz but this would sacrifice clean
single pole roll off.

I wonder how come no higher-speed CRTs of this size have been
produced. I understand it's easier to precisely deflect by smaller
amounts, but I must wonder if that's such a big hurdle.
More deflection just requires higher voltage in the CRT amplifier
output stage which trades off against high bandwidth in the
transistors.

I think the big hurtle is lack of suitable high voltage fast output
transistors. High voltage LDMOS transistors are available now which
might work well in an output cascode.


 

On Fri, 12 Jul 2013 14:35:37 -0500, David <davidwhess@gmail.com>
wrote:

Tektronix used distributed deflection plates in the 475 and 7704 which
are 200 MHz. My guess is that the pole formed by the deflection plate
series inductance would limit you to about 100 MHz but that you could
compensate it out at the expense of difficult transient response
calibration to get to at least 200 MHz but this would sacrifice clean
single pole roll off.
Actually I think Tektronix used a built in T-coil design instead of
distributed deflection plates for their 200 MHz 275 and 7704 but that
does not matter for purposes of this discussion. Externally the two
designs look the same and there are 4 pins going to the vertical
deflection plates with the second pair used for the termination.


 

The vertical deflection 3dB point of the 7104 MCP CRT exceeds 3GHz.
"Exceeds" is the best Tek was able to determine since measurements at these
frequencies is not easy to do. The vertical distributed deflection plates
have a 200 ohm impedance.

Lockheed took an off the shelf 7912 CRT and used it as the heart of a soft
X-ray detector. They measured the vertical deflection 3dB point of the 7912
CRT as 3.5GHz.

The Horizontal bandwidth of the entire 7104 horizontal system from the BNC
on a 7A29 is >350MHz which is the only scope I know of with that bandwidth
on the horizontal axis.

I believe LeCroy made a faster CRT at one point. Steve Ditter may be able to
confirm what LeCroy was able to do with their fastest analog scopes.

<snip>
Interesting. How far up do you think this will go in terms of vertical
deflection? 200MHz? 400 MHz? What's the fastest oscilloscope with this type
of deflection plate arrangement?

Cheers,
Damian


Don Black <donald_black@...>
 

I think a French company (CSF?) made an analog scope that went to 7 GHz.

Don Black.

On 13-Jul-13 11:22 AM, Dennis Tillman wrote:
 

The vertical deflection 3dB point of the 7104 MCP CRT exceeds 3GHz.
"Exceeds" is the best Tek was able to determine since measurements at these
frequencies is not easy to do. The vertical distributed deflection plates
have a 200 ohm impedance.

Lockheed took an off the shelf 7912 CRT and used it as the heart of a soft
X-ray detector. They measured the vertical deflection 3dB point of the 7912
CRT as 3.5GHz.

The Horizontal bandwidth of the entire 7104 horizontal system from the BNC
on a 7A29 is >350MHz which is the only scope I know of with that bandwidth
on the horizontal axis.

I believe LeCroy made a faster CRT at one point. Steve Ditter may be able to
confirm what LeCroy was able to do with their fastest analog scopes.


Interesting. How far up do you think this will go in terms of vertical
deflection? 200MHz? 400 MHz? What's the fastest oscilloscope with this type
of deflection plate arrangement?

Cheers,
Damian



David DiGiacomo
 

On Fri, Jul 12, 2013 at 8:25 PM, Don Black <donald_black@bigpond.com> wrote:



I think a French company (CSF?) made an analog scope that went to 7 GHz.
Not a scope, and not CSF, but you got the French part right:

http://www.greenfieldtechnology.com/-Data-aquisition-system-.html


Don Black <donald_black@...>
 

I don't think that's what I had in mind. I believe there was mention of it several years ago here when there was discussion of the 7109, third party amplifiers and pushing it's bandwidth to 3 GHz. It might have been discussion around the old 519 without amplifiers, just talking about the tube frequency limit. Does anyone else remember it or are the pixies playing with my mind?

Don Black.

On 13-Jul-13 12:32 PM, David DiGiacomo wrote:
 

On Fri, Jul 12, 2013 at 8:25 PM, Don Black <donald_black@...> wrote:
>
>
>
> I think a French company (CSF?) made an analog scope that went to 7 GHz.

Not a scope, and not CSF, but you got the French part right:

http://www.greenfieldtechnology.com/-Data-aquisition-system-.html



Cliff White
 

Here's what I think you're remembering: http://w140.com/kurt/campbell83/

Image 5 talks about a French 7GHz one, page one has a Russian 7Ghz scope, and there's lots of other goodies in between!



Respectfully,
Cliff White, W5CNW
w5cnw@...

On 07/12/2013 09:59 PM, Don Black wrote:
 

I don't think that's what I had in mind. I believe there was mention of it several years ago here when there was discussion of the 7109, third party amplifiers and pushing it's bandwidth to 3 GHz. It might have been discussion around the old 519 without amplifiers, just talking about the tube frequency limit. Does anyone else remember it or are the pixies playing with my mind?

Don Black.

On 13-Jul-13 12:32 PM, David DiGiacomo wrote:

 

On Fri, Jul 12, 2013 at 8:25 PM, Don Black <donald_black@...> wrote:
>
>
>
> I think a French company (CSF?) made an analog scope that went to 7 GHz.

Not a scope, and not CSF, but you got the French part right:

http://www.greenfieldtechnology.com/-Data-aquisition-system-.html




 

On Fri, 12 Jul 2013 14:35:37 -0500, David <davidwhess@gmail.com>
wrote:

On Fri, 12 Jul 2013 20:21:10 +0200, "cheater00 ."
<cheater00@gmail.com> wrote:

David,

On Fri, Jul 12, 2013 at 3:03 PM, David <davidwhess@gmail.com> wrote:
The horizontal bandwidth is usually limited by the horizontal CRT
amplifier which is designed for linearity at the expense of bandwidth.

CRT bandwidth is ultimately limited by the deflection plate design.
CRTs faster than the 760x have distributed vertical deflection plates
to support bandwidths above 100 MHz. The 7104 CRT has distributed
horizontal deflection plates to support a 250 MHz horizontal bandwidth
with a horizontal CRT amplifier that looks more like the vertical CRT
amplifier in a slower oscilloscope.

So the 760x CRT should support at least 100 MHz in either direction
and the difference in horizontal and vertical bandwidth is mostly
because of the CRT amplifiers. You could always test it by turning
the CRT 90 degrees and hooking it up.

The 760x CRT bandwidth ultimately depends on the lumped nature of the
deflection plates. You could drive them with a lower impedance
amplifier up to the point where the series inductance becomes a
limiting factor.
Interesting. How far up do you think this will go in terms of vertical
deflection? 200MHz? 400 MHz? What's the fastest oscilloscope with this
type of deflection plate arrangement?
If you study the Tektronix Circuit Concept documents on vertical
amplifiers and CRTs, you can find two different limits on CRT
bandwidth:

1. The lumped deflection plate load on the vertical CRT amplifier will
limit deflection frequency response. The 200 MHz Tektronix CRTs use
impedance matching and CRT terminations to help with this but with
care, I think you could compensate for this in the vertical amplifier.
That would get the 7603 CRT up to at least 200 MHz.

2. The transit time of the electrons past the deflection plates
creates a sin(x)/x type of frequency response. Tektronix CRTs faster
than 200 MHz use distributed deflection plates to get around this
limitation by having the deflection voltage wave pace the electrons.
If this was a problem, then I think you could alter the cathode
voltage to change the electron velocity past the deflection plates and
trade off deflection sensitivity for bandwidth but then the deflection
amplifier would need to produce a higher output voltage to get the
same deflection.


 

As far as I know the Tek 7104 CRT is the fastest true CRT that is directly viewed.

 

Most, if not all, of the scopes or CRTs that go faster than 3GHz are indirect display devices that rely on another technology for temporary storage and readout of the data.

 

Dennis

 

From: Don Black, Sent: Friday, July 12, 2013 7:26 PM
I think a French company (CSF?) made an analog scope that went to 7 GHz.
Don Black.


-----Original Message-----
From: David DiGiacomo, Sent: Friday, July 12, 2013 7:33 PM

> I think a French company (CSF?) made an analog scope that went to 7 GHz.

Not a scope, and not CSF, but you got the French part right:

http://www.greenfieldtechnology.com/-Data-aquisition-system-.html


 

Hi Don,

 

There was no 7109. But you may be thinking of something B&H Engineering (Bernie and Harvey Horowitz, Monroe, NY) made. They modified a Tek 7104 to take advantage of the exquisite 1 V/Div vertical deflection sensitivity of the 3GHz CRT. The did this by removing the entire vertical interface, differential delay line, and vertical amplifier and replacing it with a single ended connection using a proprietary 3GHz amplifier module they developed.

 

They designed two vertical amplifier plugins for it. The M2000 was a 3GHz, 50 ohm plugin and the M3000 was similar except it had a variable delay feature. The output of both plugins was single ended and coupled to the mainframe using a SMB connector. The heart of these two plugins is a single module made from discrete parts for amplification, the 3002, which they designed and sold. The module was not Gaussian. It had terrible overshoot and ringing.

 

They don’t remember if they made 2 or 3 complete systems for the Navy. I have one of each of the vertical plugins. I met with them last month to learn the fate of the mainframes in hopes I could get one donated to the VintageTEK museum but they were given to the Navy for whom they were developed and lost track of them.

 

From the exterior, the 7104 they modified looks exactly like a conventional 7104. If you open one up it would become immediately obvious that the vertical amplifier was removed and replaced with a 2” x 2” module which directly drove the vertical deflection plates.

 

There is no way to verify their claim that this scope was capable of 3GHz. The technology to do that didn’t exist in a form that a small company of their size could afford at that time. Even Tek was unable to confirm the performance of the CRT beyond 3GHz.

 

Dennis

 

From: Don Black, Sent: Friday, July 12, 2013 8:00 PM

I don't think that's what I had in mind. I believe there was mention of it several years ago here when there was discussion of the 7109, third party amplifiers and pushing it's bandwidth to 3 GHz. It might have been discussion around the old 519 without amplifiers, just talking about the tube frequency limit. Does anyone else remember it or are the pixies playing with my mind?

Don Black.


Don Black <donald_black@...>
 

Thanks Cliff, that's probably the equipment I was thinking of, quite remarkable performance for its time. Keeping to the Tektronix theme, the time line shows the 519C as a 3 GHz scope but with only 180 vols / cm sensitivity. I can't recall anything about this version, perhaps a few hand made specials for the nuclear laboratories? Does anyone know any details (manual, hen's teeth??).
It's interesting how most of the scopes current in 1983 used MCPs  and mention was made of one failure due to the MCP after 9000 hrs. In light of discussion about the 7104 MCP fragility that sounds like a long life.

Don Black.

Don Black

On 13-Jul-13 1:28 PM, Cliff White wrote:
 

Here's what I think you're remembering: http://w140.com/kurt/campbell83/

Image 5 talks about a French 7GHz one, page one has a Russian 7Ghz scope, and there's lots of other goodies in between!



Respectfully,
Cliff White, W5CNW
w5cnw@...
On 07/12/2013 09:59 PM, Don Black wrote:
 

I don't think that's what I had in mind. I believe there was mention of it several years ago here when there was discussion of the 7109, third party amplifiers and pushing it's bandwidth to 3 GHz. It might have been discussion around the old 519 without amplifiers, just talking about the tube frequency limit. Does anyone else remember it or are the pixies playing with my mind?

Don Black.

On 13-Jul-13 12:32 PM, David DiGiacomo wrote:

 

On Fri, Jul 12, 2013 at 8:25 PM, Don Black <donald_black@...> wrote:
>
>
>
> I think a French company (CSF?) made an analog scope that went to 7 GHz.

Not a scope, and not CSF, but you got the French part right:

http://www.greenfieldtechnology.com/-Data-aquisition-system-.html





Don Black <donald_black@...>
 

Thanks Dennis, the 7109 was a typo, meant 7104 (that sounds better than senior moment ;) ). I was aware of the examples of higher bandwidth special amplifiers using the 7104 and the trade off of frequency at the expense of bad transient response. However it's good to see your more detailed description. I thought some of the foreign GHz scopes might have been direct view but you may be right about them all being coupled to readout tubes. I guess the old 519C was direst view without any MCP.
It would be interesting to know what they used the modified 3GHz 7104 system for. If it was impulse work the poor transient response would seem significant (I wonder if they could analyze the results and allow for the pulse distortion)? If it was just frequency response then something like a sampling scope or spectrum analyzer would seem better. Perhaps they just did it to prove they could (higher, faster, stronger).

Don Black.

On 13-Jul-13 2:57 PM, Dennis Tillman wrote:
 

Hi Don,

 

There was no 7109. But you may be thinking of something B&H Engineering (Bernie and Harvey Horowitz, Monroe, NY) made. They modified a Tek 7104 to take advantage of the exquisite 1 V/Div vertical deflection sensitivity of the 3GHz CRT. The did this by removing the entire vertical interface, differential delay line, and vertical amplifier and replacing it with a single ended connection using a proprietary 3GHz amplifier module they developed.

 

They designed two vertical amplifier plugins for it. The M2000 was a 3GHz, 50 ohm plugin and the M3000 was similar except it had a variable delay feature. The output of both plugins was single ended and coupled to the mainframe using a SMB connector. The heart of these two plugins is a single module made from discrete parts for amplification, the 3002, which they designed and sold. The module was not Gaussian. It had terrible overshoot and ringing.

 

They don’t remember if they made 2 or 3 complete systems for the Navy. I have one of each of the vertical plugins. I met with them last month to learn the fate of the mainframes in hopes I could get one donated to the VintageTEK museum but they were given to the Navy for whom they were developed and lost track of them.

 

From the exterior, the 7104 they modified looks exactly like a conventional 7104. If you open one up it would become immediately obvious that the vertical amplifier was removed and replaced with a 2” x 2” module which directly drove the vertical deflection plates.

 

There is no way to verify their claim that this scope was capable of 3GHz. The technology to do that didn’t exist in a form that a small company of their size could afford at that time. Even Tek was unable to confirm the performance of the CRT beyond 3GHz.

 

Dennis

 

From: Don Black, Sent: Friday, July 12, 2013 8:00 PM

I don't think that's what I had in mind. I believe there was mention of it several years ago here when there was discussion of the 7109, third party amplifiers and pushing it's bandwidth to 3 GHz. It might have been discussion around the old 519 without amplifiers, just talking about the tube frequency limit. Does anyone else remember it or are the pixies playing with my mind?

Don Black.



 

Hi Don,

 

They didn’t know what the Navy was going to use it for. They told me it was a Navy contract and they were not told what they were used for (or wouldn’t say). I suspect that when the Navy got the instruments they were not impressed with the performance. I also suspect this was a Pork Barrel contract from their local congressman

 

The remarkable thing is that these two engineers were able to build something that had the appearance of being plausible. From an engineering standpoint it was a sort of doppelganger. It caused a few people at Tek to sit up and take notice. Eventually, from even 3000 miles away, Tek realized it was not practical to do. If the folks at Tek had actually seen how B&H gutted several of the 7104 subsystems that are fundamental to all analog scopes they would have laughed at it.

 

To their credit I have to say that for Bernie and Harvey to even think it might be possible to do something like this took either bold imagination or chutzpah.

 

Dennis

 

From: Don Black, Sent: Friday, July 12, 2013 10:22 PM

Thanks Dennis, the 7109 was a typo, meant 7104 (that sounds better than senior moment ;) ). I was aware of the examples of higher bandwidth special amplifiers using the 7104 and the trade off of frequency at the expense of bad transient response. However it's good to see your more detailed description. I thought some of the foreign GHz scopes might have been direct view but you may be right about them all being coupled to readout tubes. I guess the old 519C was direst view without any MCP.
It would be interesting to know what they used the modified 3GHz 7104 system for. If it was impulse work the poor transient response would seem significant (I wonder if they could analyze the results and allow for the pulse distortion)? If it was just frequency response then something like a sampling scope or spectrum analyzer would seem better. Perhaps they just did it to prove they could (higher, faster, stronger).

Don Black.


On 13-Jul-13 2:57 PM, Dennis Tillman wrote:

Hi Don,

There was no 7109. But you may be thinking of something B&H Engineering (Bernie and Harvey Horowitz, Monroe, NY) made. They modified a Tek 7104 to take advantage of the exquisite 1 V/Div vertical deflection sensitivity of the 3GHz CRT. The did this by removing the entire vertical interface, differential delay line, and vertical amplifier and replacing it with a single ended connection using a proprietary 3GHz amplifier module they developed.

They designed two vertical amplifier plugins for it. The M2000 was a 3GHz, 50 ohm plugin and the M3000 was similar except it had a variable delay feature. The output of both plugins was single ended and coupled to the mainframe using a SMB connector. The heart of these two plugins is a single module made from discrete parts for amplification, the 3002, which they designed and sold. The module was not Gaussian. It had terrible overshoot and ringing.

They don’t remember if they made 2 or 3 complete systems for the Navy. I have one of each of the vertical plugins. I met with them last month to learn the fate of the mainframes in hopes I could get one donated to the VintageTEK museum but they were given to the Navy for whom they were developed and lost track of them.

From the exterior, the 7104 they modified looks exactly like a conventional 7104. If you open one up it would become immediately obvious that the vertical amplifier was removed and replaced with a 2” x 2” module which directly drove the vertical deflection plates.

There is no way to verify their claim that this scope was capable of 3GHz. The technology to do that didn’t exist in a form that a small company of their size could afford at that time. Even Tek was unable to confirm the performance of the CRT beyond 3GHz.

Dennis

From: Don Black, Sent: Friday, July 12, 2013 8:00 PM

I don't think that's what I had in mind. I believe there was mention of it several years ago here when there was discussion of the 7109, third party amplifiers and pushing it's bandwidth to 3 GHz. It might have been discussion around the old 519 without amplifiers, just talking about the tube frequency limit. Does anyone else remember it or are the pixies playing with my mind?

Don Black.


 

Hi Dennis,

On Sat, Jul 13, 2013 at 6:57 AM, Dennis Tillman <dennis@ridesoft.com> wrote:
They designed two vertical amplifier plugins for it. The M2000 was a 3GHz, 50 ohm plugin and the M3000 was similar except it had a variable delay feature. The output of both plugins was single ended and coupled to the mainframe using a SMB connector.
I have one of each of the vertical plugins.
What you have is M1000 and M2000. The M1000 doesn't have the rear
connector BNC, only the M2000. How's the remainder of the red paint on
that one holding up?

The module was not Gaussian. It had terrible overshoot and ringing.
What does "Gaussian" mean precisely in this context? I don't know
where to look for a definition. Sounds like something I should know.

Cheers,
D.


 

Hi guys,
thanks for the amazing replies, that's some great food for thought.
I'm especially thrilled to find out about the 519/519C.
I'm very happy to have found out about the French company Thomson-CSF
and the American EG&G. Something to look out for in the future.

Cheers,
D.

On Sat, Jul 13, 2013 at 6:14 AM, David <davidwhess@gmail.com> wrote:
On Fri, 12 Jul 2013 14:35:37 -0500, David <davidwhess@gmail.com>
wrote:

On Fri, 12 Jul 2013 20:21:10 +0200, "cheater00 ."
<cheater00@gmail.com> wrote:

David,

On Fri, Jul 12, 2013 at 3:03 PM, David <davidwhess@gmail.com> wrote:
The horizontal bandwidth is usually limited by the horizontal CRT
amplifier which is designed for linearity at the expense of bandwidth.

CRT bandwidth is ultimately limited by the deflection plate design.
CRTs faster than the 760x have distributed vertical deflection plates
to support bandwidths above 100 MHz. The 7104 CRT has distributed
horizontal deflection plates to support a 250 MHz horizontal bandwidth
with a horizontal CRT amplifier that looks more like the vertical CRT
amplifier in a slower oscilloscope.

So the 760x CRT should support at least 100 MHz in either direction
and the difference in horizontal and vertical bandwidth is mostly
because of the CRT amplifiers. You could always test it by turning
the CRT 90 degrees and hooking it up.

The 760x CRT bandwidth ultimately depends on the lumped nature of the
deflection plates. You could drive them with a lower impedance
amplifier up to the point where the series inductance becomes a
limiting factor.
Interesting. How far up do you think this will go in terms of vertical
deflection? 200MHz? 400 MHz? What's the fastest oscilloscope with this
type of deflection plate arrangement?
If you study the Tektronix Circuit Concept documents on vertical
amplifiers and CRTs, you can find two different limits on CRT
bandwidth:

1. The lumped deflection plate load on the vertical CRT amplifier will
limit deflection frequency response. The 200 MHz Tektronix CRTs use
impedance matching and CRT terminations to help with this but with
care, I think you could compensate for this in the vertical amplifier.
That would get the 7603 CRT up to at least 200 MHz.

2. The transit time of the electrons past the deflection plates
creates a sin(x)/x type of frequency response. Tektronix CRTs faster
than 200 MHz use distributed deflection plates to get around this
limitation by having the deflection voltage wave pace the electrons.
If this was a problem, then I think you could alter the cathode
voltage to change the electron velocity past the deflection plates and
trade off deflection sensitivity for bandwidth but then the deflection
amplifier would need to produce a higher output voltage to get the
same deflection.


------------------------------------

Yahoo! Groups Links



 

Yes, you are correct. They are M1000 and M2000. I'm VERY curious how you
knew. Was it a prior posting of mine?

For a good explanation of Gaussian Oscilloscope Response see this article
http://www.eetimes.com/document.asp?doc_id=1276244

Dennis

-----Original Message-----
From: cheater00 ., Sent: Saturday, July 13, 2013 3:42 AM

Hi Dennis,

On Sat, Jul 13, 2013 at 6:57 AM, Dennis Tillman <dennis@ridesoft.com> wrote:
They designed two vertical amplifier plugins for it. The M2000 was a 3GHz,
50 ohm plugin and the M3000 was similar except it had a variable delay
feature. The output of both plugins was single ended and coupled to the
mainframe using a SMB connector.
I have one of each of the vertical plugins.
What you have is M1000 and M2000. The M1000 doesn't have the rear connector
BNC, only the M2000. How's the remainder of the red paint on that one
holding up?

The module was not Gaussian. It had terrible overshoot and ringing.
What does "Gaussian" mean precisely in this context? I don't know where to
look for a definition. Sounds like something I should know.

Cheers,
D.


bobworsley92 <bobworsley92@...>
 

Yes, correct, it was Thomson CSF who made a real time oscilloscope that worked to 4GHz, -3dB, model TSN-660.

I did used to have a few, but they were so large in the end they got scrapped, but I still have the operating and service manuals.

They didn't use any Y amplifier. The MCP CRT was over 3' long and relied on the distributed plates to get the signal sensitivity. Getting to be a long time ago but it was about 1 to 2V per division. Can't remember the maximum sweep speed either, and couldn't quickly find in the manual, but it was something silly like 50pS/div.

The timebase used avalanche transistors to get the required voltage rise time. The output amplifier used +/-600V DC supplies of which the few volts around zero actually were used. Due to the power consumed the maximum sweeps were 25 per second.

The scopes worked, and in subdued lighting you could see a rise time of 10s of picoseconds.

Amazing scopes, think they came from Imperial College in London, can't remember. Not your everyday scope, they weighed well over 50kg plus the signal delay line, and in a box 4' by 2' by 15". I did sell two of the scopes, whether they are still in existence I don't know, all I have are a few spares like the tunnel diode trigger unit.

So yes, the French made a real time scope much faster than the 7104. And because there were no amplifiers there is also the 6dB decade roll off, like a sampling scope, giving a much wider bandwidth than an amplified scope.

Bob

--- In TekScopes@yahoogroups.com, Don Black <donald_black@...> wrote:

I /think/ a French company (CSF?) made an analog scope that went to 7 GHz.

Don Black.

On 13-Jul-13 11:22 AM, Dennis Tillman wrote:

The vertical deflection 3dB point of the 7104 MCP CRT exceeds 3GHz.
"Exceeds" is the best Tek was able to determine since measurements at
these
frequencies is not easy to do. The vertical distributed deflection plates
have a 200 ohm impedance.

Lockheed took an off the shelf 7912 CRT and used it as the heart of a soft
X-ray detector. They measured the vertical deflection 3dB point of the
7912
CRT as 3.5GHz.

The Horizontal bandwidth of the entire 7104 horizontal system from the BNC
on a 7A29 is >350MHz which is the only scope I know of with that bandwidth
on the horizontal axis.

I believe LeCroy made a faster CRT at one point. Steve Ditter may be
able to
confirm what LeCroy was able to do with their fastest analog scopes.

<snip>
Interesting. How far up do you think this will go in terms of vertical
deflection? 200MHz? 400 MHz? What's the fastest oscilloscope with this
type
of deflection plate arrangement?

Cheers,
Damian