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On Sun, 28 Jul 2013 20:34:35 +0200, "cheater00 ." <cheater00@gmail.com> wrote: On 28 Jul 2013 20:13, "David" <davidwhess@gmail.com> wrote:
The 7L5, 7L14 and 7L18 spectrum analyzer plug-ins have storage so they
should not be used. In general *any* plug-in which generates a slow
continuous sweep or vector graphics should not be used which would
include the 7L13 spectrum analyzer which does not have storage.
The readout is vector generated but considered a necessary evil and
only affects the top and bottom border area of the CRT.
Thanks, makes sense. What if one modulated the signal e.g. with a sine
wave... might not be so damaging then?
Given readout is fully digital. I'm surprised no one came up with an LCD
readout mod ... 20 years ago. My understanding is that the MCP cells just have a finite limit to the number of electrons they can amplify so damage is cummulative with the gain in each cell diminishing over time. In a continuous tone application like a low light image amplifier tube, this is not as serious a limitation because the whole MCP will tend to wear evenly but with an oscilloscope, wear is limited to very sharply defined areas where the CRT beam scans. I think later MCPs were a lot tougher than the 7104 MCP. Philips used dedicated LCDs for the readout information but displaying the readout on the CRT has the advantage of allowing complete documentation via a camera attachment. Tektronix even made a 7000 plug-in, the 7M13, to take advantage of this by generating custom readouts in one slot.
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On 28 Jul 2013 20:55, "David" <davidwhess@...> wrote:
>
> On Sun, 28 Jul 2013 20:34:35 +0200, "cheater00 ."
> <cheater00@...> wrote:
>
> >On 28 Jul 2013 20:13, "David" <davidwhess@...> wrote:
> >>
> >> The 7L5, 7L14 and 7L18 spectrum analyzer plug-ins have storage so they
> >> should not be used. In general *any* plug-in which generates a slow
> >> continuous sweep or vector graphics should not be used which would
> >> include the 7L13 spectrum analyzer which does not have storage.
> >>
> >> The readout is vector generated but considered a necessary evil and
> >> only affects the top and bottom border area of the CRT.
> >
> >Thanks, makes sense. What if one modulated the signal e.g. with a sine
> >wave... might not be so damaging then?
> >
> >Given readout is fully digital. I'm surprised no one came up with an LCD
> >readout mod ... 20 years ago.
>
> My understanding is that the MCP cells just have a finite limit to the
> number of electrons they can amplify so damage is cummulative with the
> gain in each cell diminishing over time. In a continuous tone
> application like a low light image amplifier tube, this is not as
> serious a limitation because the whole MCP will tend to wear evenly
> but with an oscilloscope, wear is limited to very sharply defined
> areas where the CRT beam scans.
>
> I think later MCPs were a lot tougher than the 7104 MCP.
Does this mean the 11302 and 2467, or were there even later MCP CRTs?
> Philips used dedicated LCDs for the readout information but displaying
> the readout on the CRT has the advantage of allowing complete
> documentation via a camera attachment. Tektronix even made a 7000
> plug-in, the 7M13, to take advantage of this by generating custom
> readouts in one slot.
I have the 7M13, but certainly a camera could take a photo of both CCD and LCD. Setting backlight intensity could take practice.
Thanks,
D.
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On Sun, 28 Jul 2013 21:23:22 +0200, "cheater00 ." <cheater00@gmail.com> wrote: On 28 Jul 2013 20:55, "David" <davidwhess@gmail.com> wrote:
On Sun, 28 Jul 2013 20:34:35 +0200, "cheater00 ."
<cheater00@gmail.com> wrote:
On 28 Jul 2013 20:13, "David" <davidwhess@gmail.com> wrote:
The 7L5, 7L14 and 7L18 spectrum analyzer plug-ins have storage so they
should not be used. In general *any* plug-in which generates a slow
continuous sweep or vector graphics should not be used which would
include the 7L13 spectrum analyzer which does not have storage.
The readout is vector generated but considered a necessary evil and
only affects the top and bottom border area of the CRT.
Thanks, makes sense. What if one modulated the signal e.g. with a sine
wave... might not be so damaging then?
Given readout is fully digital. I'm surprised no one came up with an LCD
readout mod ... 20 years ago. My understanding is that the MCP cells just have a finite limit to the
number of electrons they can amplify so damage is cummulative with the
gain in each cell diminishing over time. In a continuous tone
application like a low light image amplifier tube, this is not as
serious a limitation because the whole MCP will tend to wear evenly
but with an oscilloscope, wear is limited to very sharply defined
areas where the CRT beam scans.
I think later MCPs were a lot tougher than the 7104 MCP.
Does this mean the 11302 and 2467, or were there even later MCP CRTs? I mean later MCP CRTs which are still used in some specialized applications. I base this on the links posted here in a MCP discussion thread some time ago which discussed MCP lifetime and wearout mechanisms. I suspect the MCPs Tektronix used had unusually short rated lifetimes but maybe they wear out quickly because of how they are applied.
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Don Black <donald_black@...>
I don't have experience with MCPs but their glass channel wear out
sounds similar to the problems with Image Orthicon camera tube
targets. These are thin glass discs that have an electron image
built up on the lmage side which has to leak through the glass
between scans to form a charge on the scanned side. The original
targets were made of doped glass that was slightly "ionic"conductive
and they only had a life of a few hundred hours before they wore out
as their resistance increased. A different type of glass was
introduced (by EEV I think) called Elcon (electron Conduction) that
used a resistive mode and that increased tube life ten fold plus was
much less prone to "sticking" (image retention) than the old type. I
guess similar developments were made to the glass channels in MCPs.
Don Black.
toggle quoted messageShow quoted text
I mean later MCP CRTs which are still used in some
specialized
applications. I base this on the links posted here in a
MCP
discussion thread some time ago which discussed MCP
lifetime and
wearout mechanisms. I suspect the MCPs Tektronix used had
unusually
short rated lifetimes but maybe they wear out quickly
because of how
they are applied.
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The mention to Image Orthicons reminds me that the cameras that used
them normally had a feature called "Orbital". This was a device
that avoided that a static image could became fixed to the sensitive
target making the tube useless. I think that some of them used a
motor to slow drive (1 cycle per min or so) a potentiometer to send
sine-cosine currents to a pair of deflecting coils. The image
movement was quite small but enough for saving the TV camera to
become a photo camera.
This could be done for MCP scopes and wisely designed it could
operate only when the readout was in action without affecting the
normal traces. Maybe it is a good idea for a backwards patent that
now is useless.
Regards,
Ignacio EB4APL
toggle quoted messageShow quoted text
On 29/07/2013 1:21, Don Black wrote:
I don't have experience with MCPs but their glass
channel wear out sounds similar to the problems with Image
Orthicon camera tube targets. These are thin glass discs
that have an electron image built up on the lmage side
which has to leak through the glass between scans to form
a charge on the scanned side. The original targets were
made of doped glass that was slightly "ionic"conductive
and they only had a life of a few hundred hours before
they wore out as their resistance increased. A different
type of glass was introduced (by EEV I think) called Elcon
(electron Conduction) that used a resistive mode and that
increased tube life ten fold plus was much less prone to
"sticking" (image retention) than the old type. I guess
similar developments were made to the glass channels in
MCPs.
Don Black.
I mean later MCP CRTs which are still used in some
specialized
applications. I base this on the links posted here
in a MCP
discussion thread some time ago which discussed
MCP lifetime and
wearout mechanisms. I suspect the MCPs Tektronix
used had unusually
short rated lifetimes but maybe they wear out
quickly because of how
they are applied.
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Don Black <donald_black@...>
That's interesting Ignacio. I guess from your email address you're
in Spain (I'm in Australia, though my ISP doesn't have the AU tag
available grrr). I think I've heard of the "Orbital" function but
the cameras I worked on (Marconi and Pye" didn't have it. What
cameras do you know used it?
I guess the scopes could be fitted with something similar, at least
for moving the readout around. It might be a problem moving the
trace it you were trying to line it up with the graticule to take
measurements.
Don Black
toggle quoted messageShow quoted text
On 29-Jul-13 11:18 AM, EB4APL wrote:
The mention to Image Orthicons reminds me that the
cameras that used them normally had a feature called
"Orbital". This was a device that avoided that a static
image could became fixed to the sensitive target making
the tube useless. I think that some of them used a motor
to slow drive (1 cycle per min or so) a potentiometer to
send sine-cosine currents to a pair of deflecting coils.
The image movement was quite small but enough for saving
the TV camera to become a photo camera.
This could be done for MCP scopes and wisely designed it
could operate only when the readout was in action without
affecting the normal traces. Maybe it is a good idea for
a backwards patent that now is useless.
Regards,
Ignacio EB4APL
On 29/07/2013 1:21, Don Black
wrote:
I don't have experience with MCPs but their glass
channel wear out sounds similar to the problems with
Image Orthicon camera tube targets. These are thin
glass discs that have an electron image built up on
the lmage side which has to leak through the glass
between scans to form a charge on the scanned side.
The original targets were made of doped glass that was
slightly "ionic"conductive and they only had a life of
a few hundred hours before they wore out as their
resistance increased. A different type of glass was
introduced (by EEV I think) called Elcon (electron
Conduction) that used a resistive mode and that
increased tube life ten fold plus was much less prone
to "sticking" (image retention) than the old type. I
guess similar developments were made to the glass
channels in MCPs.
Don Black.
I mean later MCP CRTs which are still used in
some specialized
applications. I base this on the links posted
here in a MCP
discussion thread some time ago which
discussed MCP lifetime and
wearout mechanisms. I suspect the MCPs
Tektronix used had unusually
short rated lifetimes but maybe they wear out
quickly because of how
they are applied.
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What I remember from the research papers discussing the problem is that the electron donor in the MCPs channels gets chemically changed or eroded in a way that seems similar to how the early unprotected screen phosphors were easily damaged and wore out quickly. As the electron donor surface area decreases, the gain goes down but for a given electron current, it also decreases slower so exhaustion follows a logarithmic curve. It is like there is a fixed number of electrons available for multiplication per unit of area. The interesting part is that apparently intensity has nothing to do with it. The damage is cumulative at any level of brightness. Luckily at normal levels of trace brightness, the lifetime is very long. On Mon, 29 Jul 2013 09:21:40 +1000, Don Black <donald_black@bigpond.com> wrote: I don't have experience with MCPs but their glass channel wear out
sounds similar to the problems with Image Orthicon camera tube targets.
These are thin glass discs that have an electron image built up on the
lmage side which has to leak through the glass between scans to form a
charge on the scanned side. The original targets were made of doped
glass that was slightly "ionic"conductive and they only had a life of a
few hundred hours before they wore out as their resistance increased. A
different type of glass was introduced (by EEV I think) called Elcon
(electron Conduction) that used a resistive mode and that increased tube
life ten fold plus was much less prone to "sticking" (image retention)
than the old type. I guess similar developments were made to the glass
channels in MCPs.
Don Black.
I mean later MCP CRTs which are still used in some specialized
applications. I base this on the links posted here in a MCP
discussion thread some time ago which discussed MCP lifetime and
wearout mechanisms. I suspect the MCPs Tektronix used had unusually
short rated lifetimes but maybe they wear out quickly because of how
they are applied.
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raymonddompfrank <r.domp.frank@...>
The readout in the 2467 'scope does move around. I think 8 or 16 positions. The trace is steady.
Raymond
toggle quoted messageShow quoted text
--- In TekScopes@yahoogroups.com, EB4APL <eb4apl@...> wrote:
The mention to Image Orthicons reminds me that the cameras that used
them normally had a feature called "Orbital". This was a device that
avoided that a static image could became fixed to the sensitive target
making the tube useless. I think that some of them used a motor to slow
drive (1 cycle per min or so) a potentiometer to send sine-cosine
currents to a pair of deflecting coils. The image movement was quite
small but enough for saving the TV camera to become a photo camera.
This could be done for MCP scopes and wisely designed it could operate
only when the readout was in action without affecting the normal
traces. Maybe it is a good idea for a backwards patent that now is useless.
Regards,
Ignacio EB4APL
On 29/07/2013 1:21, Don Black wrote:
I don't have experience with MCPs but their glass channel wear out
sounds similar to the problems with Image Orthicon camera tube
targets. These are thin glass discs that have an electron image built
up on the lmage side which has to leak through the glass between scans
to form a charge on the scanned side. The original targets were made
of doped glass that was slightly "ionic"conductive and they only had a
life of a few hundred hours before they wore out as their resistance
increased. A different type of glass was introduced (by EEV I think)
called Elcon (electron Conduction) that used a resistive mode and that
increased tube life ten fold plus was much less prone to "sticking"
(image retention) than the old type. I guess similar developments were
made to the glass channels in MCPs.
Don Black.
I mean later MCP CRTs which are still used in some specialized
applications. I base this on the links posted here in a MCP
discussion thread some time ago which discussed MCP lifetime and
wearout mechanisms. I suspect the MCPs Tektronix used had unusually
short rated lifetimes but maybe they wear out quickly because of how
they are applied.
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Hi Don,
I worked in the late sixties with both Marconi and Pye, and also
with Fernseh, Toshiba and Thomson cameras. The Marconi Mk IV had
the orbital function and also a switch for turning it off, only used
when taking a title or so.
Regards,
Ignacio EB4APL
toggle quoted messageShow quoted text
On 29/07/2013 3:42, Don Black wrote:
That's interesting Ignacio. I guess from your email
address you're in Spain (I'm in Australia, though my ISP
doesn't have the AU tag available grrr). I think I've
heard of the "Orbital" function but the cameras I worked
on (Marconi and Pye" didn't have it. What cameras do you
know used it?
I guess the scopes could be fitted with something similar,
at least for moving the readout around. It might be a
problem moving the trace it you were trying to line it up
with the graticule to take measurements.
Don Black
On 29-Jul-13 11:18 AM, EB4APL wrote:
The mention to Image Orthicons reminds me that the
cameras that used them normally had a feature called
"Orbital". This was a device that avoided that a
static image could became fixed to the sensitive
target making the tube useless. I think that some of
them used a motor to slow drive (1 cycle per min or
so) a potentiometer to send sine-cosine currents to a
pair of deflecting coils. The image movement was
quite small but enough for saving the TV camera to
become a photo camera.
This could be done for MCP scopes and wisely designed
it could operate only when the readout was in action
without affecting the normal traces. Maybe it is a
good idea for a backwards patent that now is useless.
Regards,
Ignacio EB4APL
On 29/07/2013 1:21, Don
Black wrote:
I don't have experience with MCPs but their
glass channel wear out sounds similar to the
problems with Image Orthicon camera tube targets.
These are thin glass discs that have an electron
image built up on the lmage side which has to leak
through the glass between scans to form a charge
on the scanned side. The original targets were
made of doped glass that was slightly
"ionic"conductive and they only had a life of a
few hundred hours before they wore out as their
resistance increased. A different type of glass
was introduced (by EEV I think) called Elcon
(electron Conduction) that used a resistive mode
and that increased tube life ten fold plus was
much less prone to "sticking" (image retention)
than the old type. I guess similar developments
were made to the glass channels in MCPs.
Don Black.
I mean later MCP CRTs which are still used
in some specialized
applications. I base this on the links
posted here in a MCP
discussion thread some time ago which
discussed MCP lifetime and
wearout mechanisms. I suspect the MCPs
Tektronix used had unusually
short rated lifetimes but maybe they wear
out quickly because of how
they are applied.
|
|
|
All of the CRT readouts I have seen shift because of thermal effects in the horizontal and vertical CRT amplifier chains. Tektronix went to considerable effort to minimize this but with their later feed-beside compensation, maybe they were finally successful enough to deliberately add a CRT readout shift function to ameliorate screen burns. The same type of thermal effect limits settling time and open loop DC gain of integrated operational amplifiers. One thing I like about the 7834 is that it has a front panel control to switch the readout from chopped to gated. Gated mode gets rid of the trace interference from the asynchronous readout chopping and also usually stops any readout wobble. The other 7000 oscilloscope have an internal switch for this function. It is usually used in conjunction with photographic exposures of single sweep events so that the readout is only drawn once. The readout jitter/wobble/wander tends to be different on each oscilloscope giving them an individual personality. If I designed a DSO, I would be tempted to duplicate that aspect in some way. On Mon, 29 Jul 2013 09:52:56 -0000, "raymonddompfrank" <r.domp.frank@wxs.nl> wrote: The readout in the 2467 'scope does move around. I think 8 or 16 positions. The trace is steady.
Raymond
--- In TekScopes@yahoogroups.com, EB4APL <eb4apl@...> wrote:
The mention to Image Orthicons reminds me that the cameras that used
them normally had a feature called "Orbital". This was a device that
avoided that a static image could became fixed to the sensitive target
making the tube useless. I think that some of them used a motor to slow
drive (1 cycle per min or so) a potentiometer to send sine-cosine
currents to a pair of deflecting coils. The image movement was quite
small but enough for saving the TV camera to become a photo camera.
This could be done for MCP scopes and wisely designed it could operate
only when the readout was in action without affecting the normal
traces. Maybe it is a good idea for a backwards patent that now is useless.
Regards,
Ignacio EB4APL
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Don Black <donald_black@...>
That's interesting Ignacio. I worked on three Marconi Mk IV cameras
as maintenance technician and can't remember the orbital function at
all. I guess it was just never used and I didn't notice it. One of
the cameras is now owned by a fellow member of the HRSA (Historical
Radio Society of Australia), I'll try and remember to ask him about
it. You live and learn.
Don Black.
toggle quoted messageShow quoted text
On 30-Jul-13 10:51 AM, EB4APL wrote:
Hi Don,
I worked in the late sixties with both Marconi and Pye,
and also with Fernseh, Toshiba and Thomson cameras. The
Marconi Mk IV had the orbital function and also a switch
for turning it off, only used when taking a title or so.
Regards,
Ignacio EB4APL
On 29/07/2013 3:42, Don Black
wrote:
That's interesting Ignacio. I guess from your email
address you're in Spain (I'm in Australia, though my
ISP doesn't have the AU tag available grrr). I think
I've heard of the "Orbital" function but the cameras I
worked on (Marconi and Pye" didn't have it. What
cameras do you know used it?
I guess the scopes could be fitted with something
similar, at least for moving the readout around. It
might be a problem moving the trace it you were trying
to line it up with the graticule to take measurements.
Don Black
On 29-Jul-13 11:18 AM, EB4APL wrote:
The mention to Image Orthicons reminds me that
the cameras that used them normally had a feature
called "Orbital". This was a device that avoided
that a static image could became fixed to the
sensitive target making the tube useless. I think
that some of them used a motor to slow drive (1
cycle per min or so) a potentiometer to send
sine-cosine currents to a pair of deflecting
coils. The image movement was quite small but
enough for saving the TV camera to become a photo
camera.
This could be done for MCP scopes and wisely
designed it could operate only when the readout
was in action without affecting the normal
traces. Maybe it is a good idea for a backwards
patent that now is useless.
Regards,
Ignacio EB4APL
On 29/07/2013 1:21, Don
Black wrote:
I don't have experience with MCPs but their
glass channel wear out sounds similar to the
problems with Image Orthicon camera tube
targets. These are thin glass discs that have
an electron image built up on the lmage side
which has to leak through the glass between
scans to form a charge on the scanned side.
The original targets were made of doped glass
that was slightly "ionic"conductive and they
only had a life of a few hundred hours before
they wore out as their resistance increased. A
different type of glass was introduced (by EEV
I think) called Elcon (electron Conduction)
that used a resistive mode and that increased
tube life ten fold plus was much less prone to
"sticking" (image retention) than the old
type. I guess similar developments were made
to the glass channels in MCPs.
Don Black.
I mean later MCP CRTs which are still
used in some specialized
applications. I base this on the links
posted here in a MCP
discussion thread some time ago which
discussed MCP lifetime and
wearout mechanisms. I suspect the MCPs
Tektronix used had unusually
short rated lifetimes but maybe they
wear out quickly because of how
they are applied.
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|
LOL. I'd add gyro sensors inside the scope. And a hidden menu that allows to activate an intentional wander of the readout (with increasing wobble over time). Then a good slap applied on the side of the scope would be sensed by the gyro and the software would make the readout fall back in the proper place and stop wobbling. Then the cycle repeats. An Easter Egg FUN to watch in action with unsuspecting users!!!!
toggle quoted messageShow quoted text
--- In TekScopes@yahoogroups.com, David <davidwhess@...> wrote: The readout jitter/wobble/wander tends to be different on each
oscilloscope giving them an individual personality. If I designed a
DSO, I would be tempted to duplicate that aspect in some way.
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Don,
I'm pretty sure the Mk IV has the orbital, in fact all cameras that
I used (I was a camera operator then) has this function and it was
always enabled except in some special cases, if not a still image
could get permanently stored in the target and the tube has to be
replaced, big money then. Maybe the only exception were a set of
then old cameras with 3 1/3 inch image orhticons manufactured by
Fernseh GmbH (or maybe they were made by Philips but sold by
Fernseh) but I don't remember it very well and more modern Fernseh
cameras has this function.
I think that the Marconi Mk IV has the orbital switch in a right
side recess, among other controls, close to the focus knob, I just
asked a friend that worked with me at that time and he agrees.
I remember also that in the Thomson cameras the orbital motion was
very noticeable and almost random making difficult to maintain a
steady pointing. This combined with a quite imaginative but very
unstable servo controlled zoom and focus controls made this series a
bear to work with. The Marconi Mk IV equipped with a Varotal lens
was my favorite, comfortable to operate, stable, reliable and with
top image quality. I used to be a video engineer also and still
remember the control panel full of controls for every need that you
may need.
Good old times ...
Ignacio
toggle quoted messageShow quoted text
On 30/07/2013 6:04, Don Black wrote:
That's interesting Ignacio. I worked on three Marconi Mk
IV cameras as maintenance technician and can't remember
the orbital function at all. I guess it was just never
used and I didn't notice it. One of the cameras is now
owned by a fellow member of the HRSA (Historical Radio
Society of Australia), I'll try and remember to ask him
about it. You live and learn.
Don Black.
On 30-Jul-13 10:51 AM, EB4APL wrote:
Hi Don,
I worked in the late sixties with both Marconi and
Pye, and also with Fernseh, Toshiba and Thomson
cameras. The Marconi Mk IV had the orbital function
and also a switch for turning it off, only used when
taking a title or so.
Regards,
Ignacio EB4APL
On 29/07/2013 3:42, Don
Black wrote:
That's interesting Ignacio. I guess from your
email address you're in Spain (I'm in Australia,
though my ISP doesn't have the AU tag available
grrr). I think I've heard of the "Orbital"
function but the cameras I worked on (Marconi and
Pye" didn't have it. What cameras do you know used
it?
I guess the scopes could be fitted with something
similar, at least for moving the readout around.
It might be a problem moving the trace it you were
trying to line it up with the graticule to take
measurements.
Don Black
On 29-Jul-13 11:18 AM, EB4APL wrote:
The mention to Image Orthicons reminds me
that the cameras that used them normally had a
feature called "Orbital". This was a device
that avoided that a static image could became
fixed to the sensitive target making the tube
useless. I think that some of them used a
motor to slow drive (1 cycle per min or so) a
potentiometer to send sine-cosine currents to
a pair of deflecting coils. The image
movement was quite small but enough for saving
the TV camera to become a photo camera.
This could be done for MCP scopes and wisely
designed it could operate only when the
readout was in action without affecting the
normal traces. Maybe it is a good idea for a
backwards patent that now is useless.
Regards,
Ignacio EB4APL
On 29/07/2013 1:21,
Don Black wrote:
I don't have experience with MCPs but
their glass channel wear out sounds
similar to the problems with Image
Orthicon camera tube targets. These are
thin glass discs that have an electron
image built up on the lmage side which has
to leak through the glass between scans to
form a charge on the scanned side. The
original targets were made of doped glass
that was slightly "ionic"conductive and
they only had a life of a few hundred
hours before they wore out as their
resistance increased. A different type of
glass was introduced (by EEV I think)
called Elcon (electron Conduction) that
used a resistive mode and that increased
tube life ten fold plus was much less
prone to "sticking" (image retention) than
the old type. I guess similar developments
were made to the glass channels in MCPs.
Don Black.
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raymonddompfrank <r.domp.frank@...>
To be perfectly clear: The 2467(B) has a feature that intentionally makes the readout make small jumps, for the sole purpose of spreading the use of microchannels (wear leveling). It's mentioned in the manual. This has nothing to do with unintentional movement due to drift or (thermal) jitter.
OT: I like my 7834 too! Nice fast scope with good, easy to use storage (forget about bistable). It easily achieves its single event writing spec. Pity it needs (?) its fan. That's my main reason for preferring my 7904 for general use, because that's "completely" silent.
Raymond
toggle quoted messageShow quoted text
--- In TekScopes@yahoogroups.com, David <davidwhess@...> wrote:
All of the CRT readouts I have seen shift because of thermal effects
in the horizontal and vertical CRT amplifier chains. Tektronix went
to considerable effort to minimize this but with their later
feed-beside compensation, maybe they were finally successful enough to
deliberately add a CRT readout shift function to ameliorate screen
burns. The same type of thermal effect limits settling time and open
loop DC gain of integrated operational amplifiers.
One thing I like about the 7834 is that it has a front panel control
to switch the readout from chopped to gated. Gated mode gets rid of
the trace interference from the asynchronous readout chopping and also
usually stops any readout wobble. The other 7000 oscilloscope have an
internal switch for this function. It is usually used in conjunction
with photographic exposures of single sweep events so that the readout
is only drawn once.
The readout jitter/wobble/wander tends to be different on each
oscilloscope giving them an individual personality. If I designed a
DSO, I would be tempted to duplicate that aspect in some way.
On Mon, 29 Jul 2013 09:52:56 -0000, "raymonddompfrank"
<r.domp.frank@...> wrote:
The readout in the 2467 'scope does move around. I think 8 or 16 positions. The trace is steady.
Raymond
--- In TekScopes@yahoogroups.com, EB4APL <eb4apl@> wrote:
The mention to Image Orthicons reminds me that the cameras that used
them normally had a feature called "Orbital". This was a device that
avoided that a static image could became fixed to the sensitive target
making the tube useless. I think that some of them used a motor to slow
drive (1 cycle per min or so) a potentiometer to send sine-cosine
currents to a pair of deflecting coils. The image movement was quite
small but enough for saving the TV camera to become a photo camera.
This could be done for MCP scopes and wisely designed it could operate
only when the readout was in action without affecting the normal
traces. Maybe it is a good idea for a backwards patent that now is useless.
Regards,
Ignacio EB4APL
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On 30 Jul 2013 23:49, "raymonddompfrank" <r.domp.frank@...> wrote:
>
> To be perfectly clear: The 2467(B) has a feature that intentionally makes the readout make small jumps, for the sole purpose of spreading the use of microchannels (wear leveling). It's mentioned in the manual. This has nothing to do with unintentional movement due to drift or (thermal) jitter.
>
> OT: I like my 7834 too! Nice fast scope with good, easy to use storage (forget about bistable). It easily achieves its single event writing spec. Pity it needs (?) its fan. That's my main reason for preferring my 7904 for general use, because that's "completely" silent.
Why not use a modern, silent fan? If there are specific parts which get hot, you might be able to use heatpipes to carry the heat out.
D.
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On Tue, 30 Jul 2013 23:52:02 +0200, "cheater00 ." <cheater00@gmail.com> wrote: On 30 Jul 2013 23:49, "raymonddompfrank" <r.domp.frank@wxs.nl> wrote:
To be perfectly clear: The 2467(B) has a feature that intentionally makes
the readout make small jumps, for the sole purpose of spreading the use of
microchannels (wear leveling). It's mentioned in the manual. This has
nothing to do with unintentional movement due to drift or (thermal) jitter.
OT: I like my 7834 too! Nice fast scope with good, easy to use storage
(forget about bistable). It easily achieves its single event writing spec.
Pity it needs (?) its fan. That's my main reason for preferring my 7904 for
general use, because that's "completely" silent.
Why not use a modern, silent fan? If there are specific parts which get
hot, you might be able to use heatpipes to carry the heat out.
D. The custom fans Tektronix used in the early 7000 oscilloscopes are very quiet anyway but they are not as quiet as the 7603 or 7904 which have no fan at all. The 7854 used a modern "silent" box fan and is relatively noisy.
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raymonddompfrank <r.domp.frank@...>
Since I'm mostly a collector/restorer, modifying, updating or upgrading doesn't appeal to me much unless inevitable, like the replacement of (tantalum) electrolytics with modern equivalents.
Apart from that, I'm lucky enough to have a 7834 in very good condition, with a very silent fan. But its *audible*, especially in a very quiet environment, which is my preference.
Raymond
toggle quoted messageShow quoted text
--- In TekScopes@yahoogroups.com, "cheater00 ." <cheater00@...> wrote:
On 30 Jul 2013 23:49, "raymonddompfrank" <r.domp.frank@...> wrote:
To be perfectly clear: The 2467(B) has a feature that intentionally makes
the readout make small jumps, for the sole purpose of spreading the use of
microchannels (wear leveling). It's mentioned in the manual. This has
nothing to do with unintentional movement due to drift or (thermal) jitter.
OT: I like my 7834 too! Nice fast scope with good, easy to use storage
(forget about bistable). It easily achieves its single event writing spec.
Pity it needs (?) its fan. That's my main reason for preferring my 7904 for
general use, because that's "completely" silent.
Why not use a modern, silent fan? If there are specific parts which get
hot, you might be able to use heatpipes to carry the heat out.
D.
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