Date   

Re: Repairing my High level Avalanche pulse Generator.300ps or better:

 

Does the sweep speed make any difference to the automatic timing
measurements? I know it has no effect on the automatic rise and fall
time measurements that my 2247A makes. I thought the 2465B and 2247A
designs functioned in a similar way.

As far as I know, the counter/timer is driven by the A and B sweep
gates from the trigger and the delayed sweep gate is only used for
gated measurements.

On Wed, 27 Mar 2013 21:43:21 -0700, "Dennis Tillman"
<dennis@ridesoft.com> wrote:

Gabriel,

Your 2465B is a very capable analog scope. I wish I had one when I was
learning electronics. I think you need to retake that 0.78nSec measurement.
I haven't used your scope but as near as I can tell the proper way to make
an accurate measurement like you are trying to do would be at the fastest
sweep speed (500pSec/Div) and with the amplitude at least 6 divisions
(200mV/Div).

The automatic risetime reading made by the 2465B is based on the amplitude
at 20% and 80% which is then extrapolated (extrapolation = an educated
guess) to the proper 10% - 90% amplitudes that risetime is traditionally
measured at. The faster the sweep and the larger the amplitude the more
likely your scope will come up with an accurate answer.

The 2465B has its own measurement errors that have to be taken into account.
For example the time base must be switched to X10 magnification to achieve
500pSec/Div which degrades the accuracy of the sweep and therefore the
risetime readings the scope is making. Likewise, the algorithm that
calculates the risetime has a fixed error factor (which the catalog does not
specify) for edge transitions that are less than 10nSec. All of these error
factors and adjustments would be listed in the specifications section of the
2465B Service Manual.


Re: Help Tektronix 466 repair advice

 

Switches that have contacts that slide and potentiometers should
always be lubricated after cleaning. The various dedicated products
for this usually use naphtha as a cleaner and poly phenyl ether or
silicon oil as a lubricant. I prefer PPE since silicon oil tends to
creep along surfaces and interfere with soldering.

I have been using this but CRC and other manufacturers have something
similar:

http://www.mgchemicals.com/products/cleaners/contact-cleaners/super-contact-cleaner-with-ppe-801b/

I saw the CRC version at Home Depot recently.

I picked up a hobby oiler in the form of a small plastic bottle with a
thin stainless steel needle and filled it with the contact cleaner and
lubricant so I can apply just the right amount without making a mess.

On Thu, 28 Mar 2013 00:51:59 -0000, "epicfatigue"
<epicfatigue@yahoo.com> wrote:

Okay well i will clean all switches and pots.

Ill clean out all the switches using isopropyl Alcohol,

Is it safe to do this with pots? or should i do that then lubricate them with a pot cleaner?


Re: Repairing my High level Avalanche pulse Generator.300ps or better:

Ed Breya
 

Yes, the output really is from the base - once the transistor enters avalanche mode, it's basically (pardon the pun) a short circuit between all of the terminals, so it doesn't matter much whether the B or E is used. That hookup probably seemed to work the best empirically - I doubt that it could have been predicted then or now, without some serious analysis.

The B-E junction is key to keeping things under control though - you need to absorb the Icbo with a low resistance in order to stand off the high collector voltage, then hit it hard with the trigger signal when necessary. When you stack multiple transistors, each needs a B-E shunt, and the breakdown will cascade through them all when conditions are set up right.

Ed

--- In TekScopes@yahoogroups.com, "iglesia_cristiana_arpas_eternas" <iglesia_cristiana_arpas_eternas@...> wrote:


Once in place on Tek Gear, this two series transistor , start to free run, mean no sync at 50khz rate.
My humble external pulse generator , take his output from the emitter, but according to Tek schematic (PG509), the output is from the base..!!!!.
The thing is that the pulse is not sharp an clean as mi elementary circuits.
Perhaps the manual has a bug, and base/emitter are reversed??.
I will check tomorrow.
Gabriel.
--- In TekScopes@yahoogroups.com, "iglesia_cristiana_arpas_eternas" <iglesia_cristiana_arpas_eternas@> wrote:

Serial connected of two SMD transistor in avalanche mode was tested and
work very fine , as well external triggering at 50khz..
Just remain putting this two series transistor in my Tek gear.

For the record this transistor/pulser was forced to free running at
490Khz pulse rate instead 50Khz and not show appreciable heat according
to my finger, really they switch very well indeed. but probably at
expense of life.
Gabriel.
PS: I'm pretty sure when flea die, reincarnate as SMD transistors!!!.
[:))]
--- In TekScopes@yahoogroups.com, "iglesia_cristiana_arpas_eternas"
<iglesia_cristiana_arpas_eternas@> wrote:

After remove some PCB cooper layer from my external avalanche pulse
fixture, this humble pulser reach the limits of my 2456B rise
time...750pS..!! y like to think that is much better that this, due
2465B limitation.
Next step:try to trigger via external pulse..next:put 2 in
series..next:install in Tek gear.
Some pic:
2465B screen shot.
<http://gyazo.com/a0de4cce5829400bdbf1239e87256d29.png?1364245527>

My humble pulser.
<http://gyazo.com/dfb650d9a6b076fe2b3fcd2952f1d876.png>
Gabriel.
--- In TekScopes@yahoogroups.com, "iglesia_cristiana_arpas_eternas"
iglesia_cristiana_arpas_eternas@ wrote:

I brought this nice and not working generator in ebay from I suppose
Forum member.
Is similar to a PG509 (thanks Forum guys), but better ,since include
a
nice attenuator which allow to obtain 25V to 250mV in 125 step.
The fact is, not come with an internal transmission line pulse
former.
For now I'm using a lenght of RG5858 adjusted to a 40nS pulse.
which
will be winding inside the plugin..
I'm waiting for a Teflon coax from a friend.
At arrival time, the generator not work right due a failure in
avalanche transistor Q100.
Replaced Q100 by a MSH10 and 2N2369 bring it to live but at 1,25ns
pulse time in the best case.
Today I just finish to check in an external fixture the smd
transistor
MMBR941, fortunately seems work fine.
rT=0,85ns(limit of my 2465B)
Natural trigger voltage was 40,5V.
Tek ask for a 75 to 80 V avalanche transistor, my next step is put 2
of them in series and see what once inside the Tektronix gear..

Unfortunately one attenuator step refuse to work,they have 3 slide
kind, near optical inspection show a mechanical failure.

A missing small cylinder transfer the movement between rotating
front
knob shaft/cam to the slide switch.

This small piece was fortunately found under the metallic
attenuator
cover, but seems the bed where be rest has broken retention arm.
Therefore , a more work to do in mechanical fashion...melt with iron
some good plastic and fix it.

If any one has a good reference/tips about the performance of this
smd
transistor will be appreciated.
By the way my test fixture is in itself a miniature pulse generator
which could be useful for some test...and very inexpensive.
Gabriel.


Re: Repairing my High level Avalanche pulse Generator.300ps or better:

 

Gabriel,

 

Your 2465B is a very capable analog scope. I wish I had one when I was learning electronics. I think you need to retake that 0.78nSec measurement. I haven’t used your scope but as near as I can tell the proper way to make an accurate measurement like you are trying to do would be at the fastest sweep speed (500pSec/Div) and with the amplitude at least 6 divisions (200mV/Div).

 

The automatic risetime reading made by the 2465B is based on the amplitude at 20% and 80% which is then extrapolated (extrapolation = an educated guess) to the proper 10% - 90% amplitudes that risetime is traditionally measured at. The faster the sweep and the larger the amplitude the more likely your scope will come up with an accurate answer.

 

The 2465B has its own measurement errors that have to be taken into account. For example the time base must be switched to X10 magnification to achieve 500pSec/Div which degrades the accuracy of the sweep and therefore the risetime readings the scope is making. Likewise, the algorithm that calculates the risetime has a fixed error factor (which the catalog does not specify) for edge transitions that are less than 10nSec. All of these error factors and adjustments would be listed in the specifications section of the 2465B Service Manual.

 

Finally, the Avalanche Pulse Generator and the Oscilloscope are a system. I suspect the actual risetime of the pulse generator is considerably faster than 0.78nSec because the rise time of both instruments do not add linearly. Instead the total system risetime is the square root of the sum of the individual rise times of the scope and the generator. Since the scope is conservatively specified at 400MHz lets assume its actual bandwidth is 500MHz. In that case its risetime will be 0.7nSec. Lets also assume the risetime of the pulse generator is 0.7nSec. Then the combined risetime of the entire system is sqrt (0.7 ^2 + 0.7 ^2) = 1.0nSec.    

 

As you learn how to include these various error factors into your measurements you will be less likely to come to incorrect conclusions, and you will be able to improve the accuracy of your measurements until they are limited only by the oscilloscope you are using.  

 

Dennis

 

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of iglesia_cristiana_arpas_eternas
Sent: Monday, March 25, 2013 2:15 PM


I'm a very happy man, after remove some parasitc capacitor due PCB layers I was abble to reach a 0,78nS in rise time, according to my 2465B automeasure function.
This small smd MMBR941 seems to work perfectly.
Next step  try to synchronize the base via external trigger pulse...next..put 2 in series...next  install on Tek.
Some pics about.
2465B screen shot of out put pulse due 10X 50 ohms external att.

My humble pulser.
Gabriel.


Re: Repairing my High level Avalanche pulse Generator.300ps or better:

 

Gabriel,

I doubt you can put two transistors in series and expect it to double the
breakdown voltage of each one individually. Each transistor will have a
different Collector to Emitter capacitance and C to E resistance while they
are non-conducting which will cause the voltage drops across them to be
(very) uneven. This will result in the voltage across one of the two
transistors being greater than its breakdown voltage before the voltage in
the PG509 can rise to the necessary 75 to 80V. At soon as one transistor
breaks down it will immediately cause the other one to breakdown.

Dennis

-----Original Message-----
From: iglesia_cristiana_arpas_eternas
Sent: Monday, March 25, 2013 1:39 PM
Subject: [TekScopes] Repairing my High level Avalanche pulse Generator.300ps
or better:

<snip>
Tek ask for a 75 to 80 V avalanche transistor, my next step is put 2 of them
in series and see what once inside the Tektronix gear..


Re: Help Tektronix 466 repair advice

epicfatigue
 

I have 99.8% just unsure if its safe to use on such an old pot, do they have a form of lubrication? will this dry it out?

--- In TekScopes@yahoogroups.com, "Tom Miller" <tmiller11147@...> wrote:

See if you can get the 99% Isopropyl Alcohol from your local pharm. They can order it in.

At the least, use the 91% stuff.


Tom

----- Original Message -----
From: epicfatigue
To: TekScopes@yahoogroups.com
Sent: Wednesday, March 27, 2013 10:24 PM
Subject: [TekScopes] Re: Help Tektronix 466 repair advice



Okay well i will clean all switches and pots.

Ill clean out all the switches using isopropyl Alcohol,

Is it safe to do this with pots? or should i do that then lubricate them with a pot cleaner?


Re: Help Tektronix 466 repair advice

 

See if you can get the 99% Isopropyl Alcohol from your local pharm. They can order it in.
 
At the least, use the 91% stuff.
 
 
Tom
 

----- Original Message -----
Sent: Wednesday, March 27, 2013 10:24 PM
Subject: [TekScopes] Re: Help Tektronix 466 repair advice

 

Okay well i will clean all switches and pots.

Ill clean out all the switches using isopropyl Alcohol,

Is it safe to do this with pots? or should i do that then lubricate them with a pot cleaner?


Re: Help Tektronix 466 repair advice

epicfatigue
 

Okay well i will clean all switches and pots.

Ill clean out all the switches using isopropyl Alcohol,

Is it safe to do this with pots? or should i do that then lubricate them with a pot cleaner?


Re: 475A and de-solder station

KJ5RV
 

Glad to hear I did not buy a problematic brand.

I have read similar techniques in their manual, but it is always good to here it from another source from a different angle. Gives one a better understanding.

Yes I though of shortening the vacuum hose, but it appears to connect inside the unit and I have not gotten around to investigating it yet. If it is long enough I may do that for short term, but my experience with vacuum hoses is it's usually best to replace the hole thing when one point fails as the rest is not far behind. Sure glad they have almost eliminated vacuum hoses from automobiles. They seem to be able to make great break and gas lines, but could never seem to make good vacuum lines.

Thank you for the information and thanks to all for the input in this thread. It has been enlightening reading them.

Steve


Re: 475A and de-solder station

Don Lewis <dlewis11193@...>
 

I have one of those 30+ year old solder suckers (O.K. Industries), ....it was VERY cheap on eBay one year.
 
Pump lasted about a week... of course no repair parts.
 
I made a 'flapper"valve out of some flexible plastic (silicone?) I found around some store-bought flowers my wife came home with from the florist.  Perfect thickness, pliability, etc.  
 
Hasn't broken in a couple of years....
 
-Don Lewis
Austin, TX (Hyde Park)
 
 
 

From: Alex
To: TekScopes@...
Sent: Wednesday, March 27, 2013 12:53 PM
Subject: [TekScopes] Re: 475A and de-solder station
 
The 707 is probably 30+ years old, Hakko no longer supports it.
I made about 10 of the valves. Should last to the Big Crunch.

--- In mailto:TekScopes%40yahoogroups.com, Dave C wrote:
>
> On Mar 26, 2013, at 12:00 PM, Alex wrote:
>
> > Also keep in mind the older pumps, like my Hakko 707 may have a disintegrated flapper valve in the pump.
> >
> > You can make your own valve from a silicone mat from a kitchen supply store.
>
> Hakko has plentiful and reasonably-priced replacement parts. I bought a new valve and other parts and rebuilt the pump valve assembly.
>
> Dave
>


Re: Help Tektronix 466 repair advice

epicfatigue
 

Okay well i will clean all switches and pots.

Ill clean out all the switches using isopropyl Alcohol,

Is it safe to do this with pots? or should i do that then lubricate them with a pot cleaner?


Re: P6247 Differential Probe Information

John Gord
 

Paul,

I once bought a lot of several P624x probes, apparently salvaged from someones "unrepairable" junk box. It looks like the most common problem is poor strain relief at the cable/probe junction, possibly made worse by a poor choice of plastic that covers the probe. The cable can be fixed with care, a magnifier and a steady hand.

--John Gord

--- In TekScopes@yahoogroups.com, "prenato_2000" <prenato_2000@...> wrote:

Does anyone here have information on the P6247 Differential Probe? What are the most common failures you have seen? Any repair info (schematics, etc) would be much appreciated.

Thanks in advance,

Paul


Re: Tektronix 7104 Available

sipespresso <sipespresso@...>
 

Perhaps you are thinking of the 6GHz Tektronix 7250, which was made by Intertechnique, which was apparently a spin-off of Thomson Semiconductor? -Kurt

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

I think I've heard of a French scope (CSF?) that went to several GHz but
don't know the details or how the transient response was. Anyone have
any details?

Don Black.

On 28-Mar-13 9:04 AM, Dennis Tillman wrote:

Hi Steve,
Yes, I was referring to "production scopes", and more specifically to
"conventional analog production scopes". Few people other than you would
know of the few, exotic, exceptions that exceeded the 1GHz limit. I am
aware
of scopes other than you cited that exceeded the 1GHz bandwidth but as you
point out they can be quite strange due to the engineering constraints
reality imposes at that frequency.

For example B&H Engineering in Yonkers NY modified the 7104 to push it to
3GHz. They were able to do this because the incredible MCP CRT of the 7104
has a 3dB deflection point in excess of 3GHz (this is documented in
the 7104
Service manual). The vertical system of the 7104 was completely removed by
B&H and they developed a single ended 3GHz vertical plugin based on a
DC to
3GHz module they designed (which had over 20% ringing at some
frequencies).

This vertical amplifier had to bypass the interface connector on the
back of
the plugin via SMB connectors that were mounted in 2 of the 4 holes at the
top of the shroud on the rear of the plugin. Once past the interface, I
believe the vertical signal was mated directly to the 7104 delay line.
Only
one CRT deflection plate was driven. I have two different B&H vertical
plugins (one has a variable delay line and the other does not) but I have
yet to find a B&H mainframe. As far as I know their scope relied on
Tek 7B10
and 7B15 time bases which were not modified so this scope would have had
trouble triggering at anything beyond what those time bases are
capable of.

It may seem like the 3GHz capability of the 7104 MCP CRT would make it
possible for Tek to have built an even faster 7104 but that was not
the case
for many reasons: The 7000 series was not designed for it and the cost
would
be prohibitive to adapt it to higher frequencies; Digital scopes were
catching up rapidly; The low cost dedicated scopes were taking their
toll on
the more expensive general purpose laboratory scopes like the 7000.

I don't believe that the 519 has better linearity than the 7104. I haven't
done a test personally although I briefly had a 519 in my home. It wasn't
mine so I didn't dare turn it on for fear that I might damage it. I
use the
7104 extensively and have never noticed a single anomaly when compared
to 3
7603s, a 7844, 7854, or 7934. John Addis and Bruce Hofer at Tek were
issued
US patent 4132958 for the Feedbeside Compensation circuit that
corrects the
amplifiers of the 7104 for thermals which is what I think you are
referring
to.

I have seen a 519 working at the VintageTEK museum and it would be
virtually
impossible to measure linearity on that tiny 2cm x 6cm screen accurately
enough to compare it to the 7cm x 9cm of the 7104. If you can get a more
precise definition of what the EG&G folks were referring to by
'linearity' I
think we can persuade the folks at the museum to do a direct comparison of
the 519 to the 7104 and take some 'linearity' measurements.

Dennis

-----Original Message-----
From: Steve
Sent: Wednesday, March 27, 2013 1:17 PM

--- In TekScopes@yahoogroups.com <mailto:TekScopes%40yahoogroups.com>,
"Dennis Tillman" <dennis@> wrote:

The 7104 that Dick is selling is the fastest analog scope ever made.
By coincidence I took this CRT photo on mine yesterday which will give
you an idea of what it is capable of. This is a 2GHz 350mV signal
displayed on the
7104 with the identical plugins that Dick has in his 7104. The 7104 is
spec'd at 1GHz. The gain at 2GHz is down by about 9X but there it is
triggering and the waveform is clear as a bell.
Dennis
Dennis,

You need to qualify that statement a bit. The 7104 is the fastest
production conventional analog scope ever made. Key qualifiers: Production
and Conventional.

The former Soviet Union built scopes for government use that were faster.
As with their scan converter digitizers, the CRTs were very long (well
over
a meter), allowing low deflection angles. These were custom built and not
sold outside of a few government labs. I have never seen one, but have
heard accounts directly from former users. They did not have microchannel
plates, so cameras were needed for single shot capture. The amplifiers
were
not DC coupled.

Iwatsu had a couple of models of scan converter based "analog scopes" that
were faster as well. These are funny animals - in one sense they act like
an analog scope, but the display is digital. No memory, and conventional
scope trigger only (no view of the pre-triggered portion of the waveform).
But they have color LCD displays with unique colors for each channel's
trace. The scan converter requires much less deflection angle than a
conventional human viewed CRT, the target being only a couple of
millimeters
high. Hence the exotic amplifier chain used in the 7104 is not required to
drive it. They are still fast amplifiers however.

I believe Iwatsu made these through the late 1990s.

The Tek 519 also has 1 GHz BW, but is direct access (input drives the CRT,
having no amplifiers) and weird deflection factors like 1.37 V/cm. The
calibrated area of the CRT is only 2 divisions high, one on either side of
ground. While these restrictions are very limiting, I have heard from
users
at EG&G that it actually has better vertical linearity that the 7104. I
have never seen a working 519 and can not verify that statement, but I
remember hearing that the linearity and thermal compensation in the
7104 are
not as good as in other Tek lab scopes. Some tradeoffs needed to be
made to
design this wonderful scope.

Steve

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

Yahoo! Groups Links


Re: Tek475: L1511 location.

Tom Jobe <tomjobe@...>
 

In the 475 service manual I have there is a picture of the corner of the mainboard where the calibrator circuit is located.
If you look at the mainboard so that the calibrator is up on the top right corner, L1511 is below that big switch where it says "beam find", and it is the second component above the largest capacitor C1505 (the largest capacitor just in that corner of the mainboard).
L1511 is an axial component that looks roughly like a one watt resistor.
tom jobe...
 
 
 
 

----- Original Message -----
From: daniel
Sent: Wednesday, March 27, 2013 2:09 PM
Subject: [TekScopes] Tek475: L1511 location.

 

Hi all.

Need help to find out, where is that inductor located.

Is part of 1khz calibrator 5vdc source along with a 150uf cap, to avoid 1khz noise, entering to 5v source .

Just could found C1511, its OK.

Guees L1511 is shorted cause I can see 1mseg period noise(20mv),on two
channels although they are shorted to GND.

Thanks in advance.


Re: Repairing my High level Avalanche pulse Generator.300ps or better:

iglesia_cristiana_arpas_eternas
 

Once in place on Tek Gear, this two series transistor , start to free run, mean no sync at 50khz rate.
My humble external pulse generator , take his output from the emitter, but according to Tek schematic (PG509), the output is from the base..!!!!.
The thing is that the pulse is not sharp an clean as mi elementary circuits.
Perhaps the manual has a bug, and base/emitter are reversed??.
I will check tomorrow.
Gabriel.

--- In TekScopes@yahoogroups.com, "iglesia_cristiana_arpas_eternas" <iglesia_cristiana_arpas_eternas@...> wrote:

Serial connected of two SMD transistor in avalanche mode was tested and
work very fine , as well external triggering at 50khz..
Just remain putting this two series transistor in my Tek gear.

For the record this transistor/pulser was forced to free running at
490Khz pulse rate instead 50Khz and not show appreciable heat according
to my finger, really they switch very well indeed. but probably at
expense of life.
Gabriel.
PS: I'm pretty sure when flea die, reincarnate as SMD transistors!!!.
[:))]
--- In TekScopes@yahoogroups.com, "iglesia_cristiana_arpas_eternas"
<iglesia_cristiana_arpas_eternas@> wrote:

After remove some PCB cooper layer from my external avalanche pulse
fixture, this humble pulser reach the limits of my 2456B rise
time...750pS..!! y like to think that is much better that this, due
2465B limitation.
Next step:try to trigger via external pulse..next:put 2 in
series..next:install in Tek gear.
Some pic:
2465B screen shot.
<http://gyazo.com/a0de4cce5829400bdbf1239e87256d29.png?1364245527>

My humble pulser.
<http://gyazo.com/dfb650d9a6b076fe2b3fcd2952f1d876.png>
Gabriel.
--- In TekScopes@yahoogroups.com, "iglesia_cristiana_arpas_eternas"
iglesia_cristiana_arpas_eternas@ wrote:

I brought this nice and not working generator in ebay from I suppose
Forum member.
Is similar to a PG509 (thanks Forum guys), but better ,since include
a
nice attenuator which allow to obtain 25V to 250mV in 125 step.
The fact is, not come with an internal transmission line pulse
former.
For now I'm using a lenght of RG5858 adjusted to a 40nS pulse.
which
will be winding inside the plugin..
I'm waiting for a Teflon coax from a friend.
At arrival time, the generator not work right due a failure in
avalanche transistor Q100.
Replaced Q100 by a MSH10 and 2N2369 bring it to live but at 1,25ns
pulse time in the best case.
Today I just finish to check in an external fixture the smd
transistor
MMBR941, fortunately seems work fine.
rT=0,85ns(limit of my 2465B)
Natural trigger voltage was 40,5V.
Tek ask for a 75 to 80 V avalanche transistor, my next step is put 2
of them in series and see what once inside the Tektronix gear..

Unfortunately one attenuator step refuse to work,they have 3 slide
kind, near optical inspection show a mechanical failure.

A missing small cylinder transfer the movement between rotating
front
knob shaft/cam to the slide switch.

This small piece was fortunately found under the metallic
attenuator
cover, but seems the bed where be rest has broken retention arm.
Therefore , a more work to do in mechanical fashion...melt with iron
some good plastic and fix it.

If any one has a good reference/tips about the performance of this
smd
transistor will be appreciated.
By the way my test fixture is in itself a miniature pulse generator
which could be useful for some test...and very inexpensive.
Gabriel.


Re: Tektronix 7104 Available

Don Black <donald_black@...>
 

I think I've heard of a French scope (CSF?) that went to several GHz but don't know the details or how the transient response was. Anyone have any details?

Don Black.

On 28-Mar-13 9:04 AM, Dennis Tillman wrote:
 

Hi Steve,
Yes, I was referring to "production scopes", and more specifically to
"conventional analog production scopes". Few people other than you would
know of the few, exotic, exceptions that exceeded the 1GHz limit. I am aware
of scopes other than you cited that exceeded the 1GHz bandwidth but as you
point out they can be quite strange due to the engineering constraints
reality imposes at that frequency.

For example B&H Engineering in Yonkers NY modified the 7104 to push it to
3GHz. They were able to do this because the incredible MCP CRT of the 7104
has a 3dB deflection point in excess of 3GHz (this is documented in the 7104
Service manual). The vertical system of the 7104 was completely removed by
B&H and they developed a single ended 3GHz vertical plugin based on a DC to
3GHz module they designed (which had over 20% ringing at some frequencies).

This vertical amplifier had to bypass the interface connector on the back of
the plugin via SMB connectors that were mounted in 2 of the 4 holes at the
top of the shroud on the rear of the plugin. Once past the interface, I
believe the vertical signal was mated directly to the 7104 delay line. Only
one CRT deflection plate was driven. I have two different B&H vertical
plugins (one has a variable delay line and the other does not) but I have
yet to find a B&H mainframe. As far as I know their scope relied on Tek 7B10
and 7B15 time bases which were not modified so this scope would have had
trouble triggering at anything beyond what those time bases are capable of.

It may seem like the 3GHz capability of the 7104 MCP CRT would make it
possible for Tek to have built an even faster 7104 but that was not the case
for many reasons: The 7000 series was not designed for it and the cost would
be prohibitive to adapt it to higher frequencies; Digital scopes were
catching up rapidly; The low cost dedicated scopes were taking their toll on
the more expensive general purpose laboratory scopes like the 7000.

I don't believe that the 519 has better linearity than the 7104. I haven't
done a test personally although I briefly had a 519 in my home. It wasn't
mine so I didn't dare turn it on for fear that I might damage it. I use the
7104 extensively and have never noticed a single anomaly when compared to 3
7603s, a 7844, 7854, or 7934. John Addis and Bruce Hofer at Tek were issued
US patent 4132958 for the Feedbeside Compensation circuit that corrects the
amplifiers of the 7104 for thermals which is what I think you are referring
to.

I have seen a 519 working at the VintageTEK museum and it would be virtually
impossible to measure linearity on that tiny 2cm x 6cm screen accurately
enough to compare it to the 7cm x 9cm of the 7104. If you can get a more
precise definition of what the EG&G folks were referring to by 'linearity' I
think we can persuade the folks at the museum to do a direct comparison of
the 519 to the 7104 and take some 'linearity' measurements.

Dennis

-----Original Message-----
From: Steve
Sent: Wednesday, March 27, 2013 1:17 PM

--- In TekScopes@..., "Dennis Tillman" wrote:
>
> The 7104 that Dick is selling is the fastest analog scope ever made.
> By coincidence I took this CRT photo on mine yesterday which will give
> you an idea of what it is capable of. This is a 2GHz 350mV signal
> displayed on the
> 7104 with the identical plugins that Dick has in his 7104. The 7104 is
> spec'd at 1GHz. The gain at 2GHz is down by about 9X but there it is
> triggering and the waveform is clear as a bell.
> Dennis

Dennis,

You need to qualify that statement a bit. The 7104 is the fastest
production conventional analog scope ever made. Key qualifiers: Production
and Conventional.

The former Soviet Union built scopes for government use that were faster.
As with their scan converter digitizers, the CRTs were very long (well over
a meter), allowing low deflection angles. These were custom built and not
sold outside of a few government labs. I have never seen one, but have
heard accounts directly from former users. They did not have microchannel
plates, so cameras were needed for single shot capture. The amplifiers were
not DC coupled.

Iwatsu had a couple of models of scan converter based "analog scopes" that
were faster as well. These are funny animals - in one sense they act like
an analog scope, but the display is digital. No memory, and conventional
scope trigger only (no view of the pre-triggered portion of the waveform).
But they have color LCD displays with unique colors for each channel's
trace. The scan converter requires much less deflection angle than a
conventional human viewed CRT, the target being only a couple of millimeters
high. Hence the exotic amplifier chain used in the 7104 is not required to
drive it. They are still fast amplifiers however.

I believe Iwatsu made these through the late 1990s.

The Tek 519 also has 1 GHz BW, but is direct access (input drives the CRT,
having no amplifiers) and weird deflection factors like 1.37 V/cm. The
calibrated area of the CRT is only 2 divisions high, one on either side of
ground. While these restrictions are very limiting, I have heard from users
at EG&G that it actually has better vertical linearity that the 7104. I
have never seen a working 519 and can not verify that statement, but I
remember hearing that the linearity and thermal compensation in the 7104 are
not as good as in other Tek lab scopes. Some tradeoffs needed to be made to
design this wonderful scope.

Steve

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

Yahoo! Groups Links



Re: Tektronix 7104 Available

Don Black <donald_black@...>
 

Very good. I believe the 519 was about 10 volts per division, the actual value for the particular scope (tube) marked on the front.

Don Black.

On 28-Mar-13 7:16 AM, Steve wrote:
 



--- In TekScopes@..., "Dennis Tillman" wrote:
>
> The 7104 that Dick is selling is the fastest analog scope ever made. By
> coincidence I took this CRT photo on mine yesterday which will give you an
> idea of what it is capable of. This is a 2GHz 350mV signal displayed on the
> 7104 with the identical plugins that Dick has in his 7104. The 7104 is
> spec'd at 1GHz. The gain at 2GHz is down by about 9X but there it is
> triggering and the waveform is clear as a bell.
>
>
>
> Dennis

Dennis,

You need to qualify that statement a bit. The 7104 is the fastest production conventional analog scope ever made. Key qualifiers: Production and Conventional.

The former Soviet Union built scopes for government use that were faster. As with their scan converter digitizers, the CRTs were very long (well over a meter), allowing low deflection angles. These were custom built and not sold outside of a few government labs. I have never seen one, but have heard accounts directly from former users. They did not have microchannel plates, so cameras were needed for single shot capture. The amplifiers were not DC coupled.

Iwatsu had a couple of models of scan converter based "analog scopes" that were faster as well. These are funny animals – in one sense they act like an analog scope, but the display is digital. No memory, and conventional scope trigger only (no view of the pre-triggered portion of the waveform). But they have color LCD displays with unique colors for each channel's trace. The scan converter requires much less deflection angle than a conventional human viewed CRT, the target being only a couple of millimeters high. Hence the exotic amplifier chain used in the 7104 is not required to drive it. They are still fast amplifiers however.

I believe Iwatsu made these through the late 1990s.

The Tek 519 also has 1 GHz BW, but is direct access (input drives the CRT, having no amplifiers) and weird deflection factors like 1.37 V/cm. The calibrated area of the CRT is only 2 divisions high, one on either side of ground. While these restrictions are very limiting, I have heard from users at EG&G that it actually has better vertical linearity that the 7104. I have never seen a working 519 and can not verify that statement, but I remember hearing that the linearity and thermal compensation in the 7104 are not as good as in other Tek lab scopes. Some tradeoffs needed to be made to design this wonderful scope.

Steve



Re: Hello ;o) plus TDS220 question

stv4st <sforrest.au@...>
 

Good idea - swapping them would certainly prove the point. I've been a bit reluctant to start pulling them apart but it looks like the time has come, at least for the problem scope...

Cheers
Stephen

--- In TekScopes@yahoogroups.com, "Hakan H" <hahi@...> wrote:



--- In TekScopes@yahoogroups.com, "stv4st" <sforrest.au@> wrote:

Hello to all!
First post...

Not quite your classic CRT Tek scope (and if there is a more appropriate forum please do direct me...) but I have an issue with a TDS220.

I bought it with a TDS2MM installed - the reason I got it in fact. Some little time later it started not starting. Sometimes when turning on the screen would just show a series of horizontal lines. Power cycling seemed to get it going (and self test was all PASSED). Then, one day, it failed in use, just the lines.

Removing the TDS2MM, the scope powered up OK, but there seems to be something screwy with the contrast. I re-installed the module and again the lines. The I put the TDS2MM into another TDS220 and all is good.

I think the issue is with the 1st TDS220. PSU not up to it? And I have just noticed a "blooming" (phase reversal?) in the lower RH corner of the display :o(

I had hoped to sell one of these scopes, and clearly I would like to keep one working with the TDS2MM.

Any thoughts?

Stephen
-----------
You could easily swap the P/S between the scopes to find out.

However the pins on the mainboard that connects to the module are quite short therefore it is very important that the module is fully seated in its compartment. If not, symptoms like scrambled display, scope won't start at all, module not recognized or all blank display may appear. Make sure it is pushed down all the way.
/Håkan


Re: Hello ;o) plus TDS220 question

stv4st <sforrest.au@...>
 

Thanks - That's where I'll start then. At least I have another scope to work with (and compare against...)

Cheers
Stephen

--- In TekScopes@yahoogroups.com, Stefan Trethan <stefan_trethan@...> wrote:

Could well be the PS.
Open it and put a scope on the power supply outputs with and without
the interface.

ST

On Tue, Mar 26, 2013 at 1:09 PM, stv4st <sforrest.au@...> wrote:
Hello to all!
First post...

Not quite your classic CRT Tek scope (and if there is a more appropriate forum please do direct me...) but I have an issue with a TDS220.

I bought it with a TDS2MM installed - the reason I got it in fact. Some little time later it started not starting. Sometimes when turning on the screen would just show a series of horizontal lines. Power cycling seemed to get it going (and self test was all PASSED). Then, one day, it failed in use, just the lines.

Removing the TDS2MM, the scope powered up OK, but there seems to be something screwy with the contrast. I re-installed the module and again the lines. The I put the TDS2MM into another TDS220 and all is good.

I think the issue is with the 1st TDS220. PSU not up to it? And I have just noticed a "blooming" (phase reversal?) in the lower RH corner of the display :o(

I had hoped to sell one of these scopes, and clearly I would like to keep one working with the TDS2MM.

Any thoughts?

Stephen





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

Yahoo! Groups Links



Re: Help Tektronix 466 repair advice

 

If the wiper of the intensity potentiometer is making intermittent
contact because it is dirty, it can cause the problem where the
intensity is either minimum or maximum. I have repaired quite a few
7000 mainframes by disassembling and cleaning the potentiometers.

On Wed, 27 Mar 2013 22:22:02 -0000, "epicfatigue"
<epicfatigue@yahoo.com> wrote:

hey thanks for that i think you might be right about the dirty switch,

as for the intensity its either all the way up or nothing at the moment think i need to re cap it.

Ill clean the whole thing out with Alc tonight and report back!.

103481 - 103500 of 192927