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Dave,

That this is the amount of ripple current the cap can take to make the lifetime spec? YES
A spec with twice the ripple for a given lifetime can take more power supply noise? YES
A UCY2C470MPD1TD with 375mA ripple and 10000 hr lifetime can take more power supply noise than a ULD1H470MED with 190mA ripple and 10000 hr lifetime? YES

The UCY is cruising in the 465 HV oscillator supply while the ULD might suffer degradation despite being well within voltage and temperature specs? MAYBE, and MAYBE not.

It depends on the actual ripple current. If say, there's only 100mA of ripple current, then both the UCY and ULD are cruising. If there's 250mA of ripple current, then that removes the ULD from the equation.

You can measure ripple current on a(nother) scope. You can FEEL how well the cap is handling ripple current by its temperature. All other factors being equal, a hot cap is battling to handle the ripple current, and a cool cap is handling the ripple current just fine. And if the cap is running hot, then the 10,000hr lifetime is meaningless.

ESR is the "internal resistance" of the cap. The lower the ESR, the more efficiently the cap is passing the current onwards. It's all about circuit efficiency, translated into MTBF, and signal cleanliness down the line. SMPS's require absolutely the lowest ESR caps possible that the bean-counters will authorize (and will stop working if a cap's ESR rises above a certain threshold), but a Linear PSU is far more tolerant of higher ESR caps.

Menahem

Steve,
The museum also has a non Facebook web page,
Once Covid is a bit more under control, the museum will be resuming in person tours.
Matt
Chief Technician LSSM

Raymond Domp Frank wrote:

The 466 is eminently suited to doing exactly what you're suggesting, much more so than even a 464.
With a 466 it's quite possible e.g. to store and then observe an edge with a rise time of 3.5 ns (the
fastest for the 100 MHz BW), either in Variable Persistence (repeating at say 1 Hz) or Fast Storage
(single shot) mode. Compare that with trying to view it on a 'scope like the 465, or for that matter,
a 475. Unless the signal has a repetition rate of at least 10 to 100 kHz, it'll be completely invisible!

That's fascinating. I might need to add the 466 to my wish list as well.

The computers that my father worked with in the late 70s had memory cycle times of 330 ns - 990 ns, so I expect that he could sustain a repetitive signal on target hardware at better than 200 kHz, so the 475 would have been able to show the signals of interest pretty easily.

Before I fell down this rabbit hole of fixing old scopes (started because the 475 malfunctioned) I was trying to use the 475 to decipher the control interface for a laptop plasma display panel. I was having some luck, but my fluency with the scope was terrible, and it was obvious that I was limited by my ignorance of how to use the delayed time base. When I've got the 475A working again I will be going back to the plasma display, and I hope that I have now learned enough about how to use the delayed time base to make better progress.

I know that this would be child's play if I just had a modern DSO, but that's not what I trying to do with this hobby, at least not right now. The 475 (and the 2200 series scopes) are exactly the right vintage to have been used with the hardware that I'm trying to investigate, and part of the fun is doing things the way that they would have been done at the time.

Of course it sounds like a 466 would make things a lot easier, while still being the proper vintage (the 468 is just slightly too new for my biases).

I have enough insight into my condition to understand that this is how one winds up with a basement full of scopes.

I get the Captcha nearly every time, and sometimes the spot-the-traffic-light game as well. They also keep enabling fast login on my iPad or computer when I don't want it, and there is no apparent way to stop that, although you can turn it off again when notified. And I can always eventually find the Send to Friend option.

I wouldn't be without it, but:

- the fees are too high considering they are holding the float and paying no interest to me.
- the UI keeps changing, and there are some things that are only accessible from the home screen, like items pending shipping for example (or else I've never found them).
- the statements are rudimentary, and when they changed from the old to the new statement format they didn't balance at the changeover point. From memory this was due to different timezones for one as against the other.
- I had a major argument with them a few years ago when their invoice form was charging GST on the undiscounted amount, meaning I was paying GST on my own discount. The call centre guy just argued black and blue until I said I wouldn't discuss it further with anyone who wasn't a qualified accountant. Eventually they put in what I wanted as an option, when the other option is never correct.
- from the programming perpsective the API is enormous and unwieldy, unless you use IPN, which is tiny and unwieldy ;-); and both are poorly documented.

EJP

That's not the worst... ask Mike how he got his first tek...

Hi Jeff,

I clearly recall using a brand new 475 at my work place some forty years ago, on which delay timer pot was not set to zero, it was set at 0.20. I don't exactly know why, but perhaps it represented the minimum inherent delay, that would always be there when using delayed sweep, due to circuit design.

My personal 465b also has this pot set at 0.20, but I am not sure whether it was set by the manufacturer, as this scope was a used, and possibly repaired one when I acquired it. Recently, I had to do some fixing on my personal 465b, and when I reassembled, I took care to set it to 0.20, whatever it means. I don't use the delayed sweep during my home use.

Hope this helps.

Shailendra

Hi Jeff,

See my embedded responses.

On Fri, Nov 27, 2020 at 03:02 AM, Jeff Dutky wrote:

It's a shame that Tek did not make a range of plugins for the 465M. It looks
like it's a lot nicer to work on than the 465/475. I wonder why they didn't
pursue that avenue of development. There is no mention of other plugin modules
for the 455 either, but that TekWiki page appears to be almost a stub.

I've sometimes wondered what the technical differences between the central modules of 455 and the 465M were but didn't bother to investigate. I only have a 455, no 465M.
I'm not sure what plugins would be possible and make sense for the 455/465M mainframe(s) but then I'm spoiled by the 7000 family. Besides, I'm sure one would have difficulty configuring the 'scope with the modules needed in preparation for on-site use, the main (intended) environment for a portable 'scope.

I'm curious about how the analog storage scopes like the 466 were used. Were
you able to get a snapshot of a single wave form? Or did this just capture a
persistent image of the repeating signal that we can see on a non-storage
scope?

The 466 is eminently suited to doing exactly what you're suggesting, much more so than even a 464. With a 466 it's quite possible e.g. to store and then observe an edge with a rise time of 3.5 ns (the fastest for the 100 MHz BW), either in Variable Persistence (repeating at say 1 Hz) or Fast Storage (single shot) mode. Compare that with trying to view it on a 'scope like the 465, or for that matter, a 475. Unless the signal has a repetition rate of at least 10 to 100 kHz, it'll be completely invisible!
That's why I love my analog storage 'scopes, at least until I pull out a reasonably modern DSO...

I remember my father using the 475 to debug minicomputer hardware. His
method involved setting the machine in a tight loop that exercised the suspect
part or function, then observing the repeated signal with the scope. Now you
would just use a DSO to capture a few microseconds of signal to memory and
wander through it at your leisure, but such a thing would have been
prohibitively expensive in 1978.

One way was using an Analog Storage 'scope as above, using the delayed time base to move the observable (B-trace) window by adjusting the delay time, until either signal- or delay time-jitter spoiled the fun. A next-level procedure in many cases then would be using the delayed time base not in the common "Runs After Delay" mode but in the "Triggerable After Delay" mode.
In those days, the operator controlled the tools, not vice versa...

Raymond

Raymon,

Yes, I saw your comments, and I agree with every one of them. I was making compromises for brevity (and personal bias).

Since I had linked to the TekWiki page I figured that any insufficiency in my descriptions could either be remedied by following the link, or that any truly gross mischaracterizations would be put aright by other comments (such as your own). I have no personal experience with anything but the 475/475A (and the 2213/2215A) so I was wary of writing too much about any of the scopes beyond what I got off the TekWiki pages.

It's a shame that Tek did not make a range of plugins for the 465M. It looks like it's a lot nicer to work on than the 465/475. I wonder why they didn't pursue that avenue of development. There is no mention of other plugin modules for the 455 either, but that TekWiki page appears to be almost a stub.

I'm curious about how the analog storage scopes like the 466 were used. Were you able to get a snapshot of a single wave form? Or did this just capture a persistent image of the repeating signal that we can see on a non-storage scope? I remember my father using the 475 to debug minicomputer hardware. His method involved setting the machine in a tight loop that exercised the suspect part or function, then observing the repeated signal with the scope. Now you would just use a DSO to capture a few microseconds of signal to memory and wander through it at your leisure, but such a thing would have been prohibitively expensive in 1978.

-- Jeff Dutky

Has anyone mentioned these folks?

Large Scale Systems Museum


They are located near Pittsburgh. I visited them a couple of years ago and
they have an amazing amount of stuff, most of which is running. Once we get
past the COVID-19 pandemic, they will likely come out (with at least a
pickup truck) and pick up a few things I have to donate. I've got an EAI
TR-20 analog computer, a couple of ROLM RuggedNOVA computers (with the
front panels), a very early Sun workstation box (long before the Pizza Box
versions - this one uses a Motorola 68000-series CPU), and a couple of
mechanical computers (an early Air Force F-111 navigational computer and
some US Navy thing - both have a large number of gears and synchros in
them; the Navy one I think also has one or two mechanical integrators). The
Large Scale Systems Museum has a lot of IBM hardware and they have it
operational. Also early DEC large computers. They may have some IBM
terminals in excess of their needs or be able to provide some
documentation. I think they had the carts full of IBM schematics that used
to live in the machine rooms with the computers for use by the service
folks. Worth a visit if you are ever near Pittsburgh. If you grew up with
this stuff as I did, it can induce some major nostalgia.

May be worth sending them an e-mail message.

Steve Horii

On Tue, Nov 24, 2020 at 10:42 AM cheater cheater <cheater00social@...>
wrote:

Hi all,
sorry for the offtopic message, not sure where to go with this one, so I
thought the smart heads around here might be connected somewhere. I'm
looking to get a 70s IBM terminal, either for a System/3, /6, /32, /38 (or
contemporary), 3600 FCS, a Display Station (or terminal) for the IBM 32xx,
37xx, 49xx, 52xx, 65xx, or 74xx, or an IBM 5100/5110/5120 portable
computer. I'm interested to see how they were built and would like to see
how it is to use them. If you know any good places to go other than the
website which should not be named, especially any forums that could have
enthusiasts of the same hardware, or if you know someone willing to part
with one such machine, let me know please.

Thanks!

Added the photo album picture number but that doesn’t link To picture.
Picture album name is Tek Glass Tracing

Photo Album
949D5068-213D-42B6-BA83-64C59169606B.jpeg

Dealing with a touch pad that has what think is glass tracing that has developed a crack thru multiple tracks. Anyone had any experience In repair of this type of situation?
This is on a Tek Ths700 séries scope

I've seen ones in worse condition but I don't have pictures. Stuff
coming back to the US from some of the NASA tracking and communications
stations on the Caribbean islands looks much worse. That one looks like it
sat in an unairconditioned outdoor storage shed for 20 years. It's rather
typical of some of the equipment that I find at garage sales here in
central Florida.

For improved PayPal security, I added the “two-factor authentication” for
PayPal since my primary payment method is a deduction from my bank checking
account. I do this for all my online banking transactions, my work and
personal e-mail (both if I am logging in from devices the mail servers do
not know are usually associated with my user name and password), and
two-factor identification running over a VPN is required for remote work
access (healthcare).

Steve H




On Thu, Nov 26, 2020 at 12:09 Frank DuVal via groups.io <corvairduval=
[email protected]> wrote:

Weird. I NEVER have a Captcha / Not A Robot screen or button when using
PayPal....

I do not save my password. Have to enter it every time, my choice. Works
for me.

I do not understand the "how far along in the buying process you are"
comment. All the screens on PayPal seem logical to me. And there are not
many when sending money, either on their website only or through a
vendor link to send funds.

So far it works well for me! Both as buyer and sending money to friends.
Even for Tek supplies, to keep it on subject.?

Frank DuVal

On 11/26/2020 1:01 AM, Jeff Dutky wrote:

I don't have particular issues, other than complaints about this
particular process (not being offered the options that would have made
this process easy), and about the quality of their buyer interface
(every time I have tried to log into their web interface I have had to
do the "I'm not a robot" dance, and every time the site has responded
with "something went wrong on our end" throwing me back to the "I'm
not a robot" screen, so that I get to do the dance again, and maybe a
third time. That's shoddy UX on PayPal's part, and I haven't got any
patience for that sort of thing. Also there's no indication of how far
along in the buying process you are, so you just have to keep clicking
Continue until suddenly the process is over. That's also shoddy UX).
My only other complaints about PayPal are mere hearsay, but I've heard
too many stories of sellers having their funds frozen over the years
to think that maybe there isn't at least a little bit of fire behind
that smoke.
That said, I understand why people want to use PayPal: they fill a niche

that, even today, has very few players. If you want to accept payment over
the web you just don't have many choices, and the established choices
(credit card merchant accounts) are not well suited to small players. When
PayPal got started they were basically the only game in town for people who
couldn't afford to set up a merchant account, and that benefit can not be
overestimated. Still, I'm a grumpy sort, and this is one of the things I'm
grumpy about.

-- Jeff Dutky

Renée, there is a lithium battery on the display & storage board which will probably need replacing; yes, the analyser will lose settings when the battery dies, however a nice feature of these analysers is that they can self calibrate and reset these values; there are some interactive settings, such as display positions that may need setting, but they are well documented in the manual. Let me know if you are having trouble finding a replacement battery, I had to buy several to satisfy the minimum order quantity from Conrad, so I have extras I'd be willing to sell.

That might be true, for something that is rarely used. If used at least
weekly, it will be fine. If it is a shelf queen, all bets are off.

On Thu, Nov 26, 2020 at 5:00 PM Glenn Little <glennmaillist@...>
wrote:

Baking the resistor will only fix it for the short term.
It will absorb moisture again as you have not fixed the problem, only
the symptom.
There is a crack or 0r other point of moisture incursion in the resistor
case.

The resistor needs to be replaced.

Glenn

On 11/26/2020 6:59 AM, Michael A. Terrell wrote:

Carbon Composition resistors absorb moisture. Bake them for a while

before

tossing them out. Also, high value resistors require voltage across them

to

work at their marked value This used to be plainly marked on reels of CC
resistors. I posted a scan once. I caught hell for 'making up that
bullshit'. They also don't realize the first resistor series was 50%
tolerance. yet they were working on pre-war radios. Once again I was told
that I was 'making up that shit'.

On Thu, Nov 26, 2020 at 12:18 AM Jeff Dutky <jeff.dutky@...>

wrote:

Tom,

Yes, I had anticipated that these NOS components might not have retained
their specified values. I've been going through my father's effects

while

working on his scopes and finding all sorts of now-50-year-old

components,

some of which were expensive when purchased new, and thinking that some
fair fraction of them are probably now terribly out of spec, if not
completely destroyed (there are a number of big metal can capacitors

that I

know were stored for at least 20 years in a hot attic, and I don't have
much hope that they are still in good condition). I purchased a dozen
resistors in the hope that I could find two that were within spec.

Back in college I worked in receiving QC for a NASA contractor that

built

flight-rated systems. We would first receive a lot of 10 or 20

components

of some description, which we would label and ship over to Goddard. They
would eventually ship us back 2 or 3 components with paint marks and
certification sheets, and we were required to use only those marked
components in the parts we built for them. The other components we had
shipped to them had been tested to destruction, and only the surviving

10%

had been returned to us as flight qualified components. Careful

selection

of parts is something I have thought about ever since.

But what you're saying is that while my intuition was correct, the

actual

math makes a fool of me. I should really just use the metal film

resistors

when they arrive because they are lower noise and the inductance is a
non-issue.

I can always gaze lovingly at the old Allen Bradleys. I'm quite sad that
nobody seems to make resistors that have those nice sharp edges anymore
(or, at least, I haven't found them for sale).

-- Jeff Dutky

--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

Hey Roger,

I tried cleaning the edge connector, but that didn't seem to help. So took
the head apart and gave the two pots as well as the board-to-board
connectors some D5 and I gave the pots each a wiggle. The "wobble" is now
gone and I have a rock-steady trace.
However, I clearly need to calibrate the head - not that it didn't already
need calibration. I guess I'll need to hunt for an extender (
) - people on
ePray sure are proud of their extenders...

In any case, thanks,
Siggi

On Mon, Nov 16, 2020 at 7:14 AM Roger Evans via groups.io <very_fuzzy_logic=
[email protected]> wrote:

Siggi,

There are two preset pots in the S6 head for gate balance (R30) and 'gain'
(R45), either could be noisy, but a more obvious suspect is the edge
connector from the S6 to the 7S12 since the DC / low frequency feedback
path has to travel through the edge connector.

Hi Jeff,
Shafts straightened with large pliers; they were only a little bent. Am considering grey PVC pipe as a knob replacement: the metal centres are still present so i just need to find a suitable diameter to fit over them.
For the 545B i have collected an assortment of eBay high voltage arc generators and LOPT's with which to experiment and replace the existing potted TX. The former have isolated secondaries, making them ideal. A theoretically possible option is some kind of large MW or LW coil that might fit over the ferrite core as a replacement secondary. I already tried driving the 6AU5 grid separately but this still takes more power than it should -and it is not difficult to have the 6AU5 anode glowing red. One could use an EL34 etc instead, assuming the unregulated 325V line has the spare capacity. Disaffected TEK EHT transformers need to operate at a lower frequency: from around 50 down to 45KHz or less. I wonder how they might manage with a 15KHz sawtooth via an EL34?
Regards

On Thu, Nov 26, 2020 at 10:46 PM, Raymond Domp Frank wrote:

At the time, the 466 was one of the fastest-storing GP portable analog storage
'scopes on the market, certainly in the 100 MHz BW range.

Sorry, incorrect. The HP 1744A was faster: 100 MHz BW, 1800 cm/us vs Tek 466 @ 1350 cm/us!
The HP was storage-only, with a very wide range of variable persistence; from almost zero to many seconds.

Raymond

On Thu, Nov 26, 2020 at 11:06 PM, Jeff Dutky wrote:

I was trying to keep the summary list short and sweet, so I omitted the A and
B versions (but included the M to illustrate the range of variation in the
models), as well as the lower bandwidth models.

Hi Jeff,
I guess you saw my comments on your summary; different summaries from different points of view, all very incomplete and personal to some degree...

Raymond

satbeginner wrote:

Add a 475A @ 250MHz to the list ;-)

I was trying to keep the summary list short and sweet, so I omitted the A and B versions (but included the M to illustrate the range of variation in the models), as well as the lower bandwidth models.

If you meant "add it to my wish list" then you're too late: I am currently restoring a 475A (as mentioned in a follow up)

-- Jeff Dutky