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On Sat, Nov 20, 2021 at 11:46 AM Roy Thistle
<roy.thistle@...> wrote:

One guy popped... and his family so hated his 'collection'... they banned everyone from the dumpsters... and smashed everything before it went in.

There is something to be said for that...

When my grandfather passed (a long while ago, whilst I was still in my
early teens), and they had to clean out the shop, my grandmother had
them take most of his electronics stuff to the dump . My impression
now is she was jealous of the stuff, he spent more time in his
workshop than he did with her...

<shrug....> It's not necessarily that the family isn't thinking,
it's that their priorities are not necessarily the same as someone
else's...

David

Hi All,

I've just uploaded a PDF I created that I hope helps describe the S-52 Pulse Generator output.

The S-52 generates a fast 25ps output edge for use in the 7S12 (and other) Time Domain Reflectometers. I was introduced to these fairly recently, and was quite confused by the Service Manual description. My S-52's behavior was suspect, and I couldn't be sure it was working or not. After help from members of this group I've come to understand its functionality a bit better and am on my way to resolving its issues.

By the way, to avoid confusion, the pictures used in the uploaded document are NOT of my S-52s output. Mine continues to not produce the pulse at the center of the waveform. Why is yet to be determined.

I don't claim to know these devices well, and I'm no great technical writer. But I hope this description clarifies this devices operation.

Dave

The following files have been uploaded to the Files area of the [email protected] group.

• /S52 Functional Description.pdf

By: Dave Peterson <davidpinsf@...>

Description:
Description of S-52 PULSE OUT cycle

Got my copy. Thanks for uploading that!

Barry - N4BUQ

On Sat, Nov 20, 2021 at 07:27 AM, Brian Symons wrote:

Some people really don't think before they act.

3 old neighbours here... all very creative hoarders ... of course I ... even if only casually.
I can say, if someone can hate an inanimate thing... the families of these guys hated their stuff.
One guy popped... and his family so hated his 'collection'... they banned everyone from the dumpsters... and smashed everything before it went in.
--
Roy Thistle

On Sat, Nov 20, 2021 at 04:01 AM, Tim Phillips wrote:

just left out in the car-park with 'Scrap' chalked on them.

Yes and sadly... much the same experience here too.
First they put it in storage, in the lab, for a decade... next they put it in storage somewhere else for a decade... next and eventually, someone discovers that that 6x10x10 storage space, and reasons they can cram a dozen grad students in there... and so out the door the stuff goes. Finally an email turns up... bunch of stuff out behind the building... if someone wants it. (That never happens until its all been sitting out there in the rain/snow, for a couple of months.)

--
Roy Thistle

Hi John,
Tunnel Diodes can be checked on a curve tracer. I will send you some resources off list in a separate E-mail. Some others here have reported that you can have a "Good" TD that is NOT GOOD at high frequency switching. Just be aware some might test good but not be good in say a trigger circuit or pulser.

Zen

On Sat, Nov 20, 2021 at 05:14 PM, John Hudak wrote:

Is there a way to test them in place? (generally speaking).

Yes, but of course it depends in what and how other components are connected to the TD.
You will get more to the point replies when you mention the type of scope and the TD number in the schematics.
Albert

Many older TEK scopes (465-475 for example) use a socketed tunnel diode. They may at first appear to be soldered, however, TEK used those miniature solder in sockets in those board locations. Same sockets that they used for their transistors.

--
Michael Lynch
Dardanelle, AR

On Sat, Nov 20, 2021 at 04:01 AM, Tim Phillips wrote:

I worked for a University in UK. Almost overnight... there was a mass dumping of analog equipment, particularly by the Biophys / Biomed groups.

Yes... I can say the experience here (were not in CONUS) was quite similar. Bio guys used to be a bunch with lots of sharp needle electrodes, sharper scalpels... and lot's, and lot's of rats (or what ever else they could catch.)... I'm still traumatised by what I saw. De rigueur for a bio path, was a first year one-semester course in into calculus, and in later years... one in intro stats.
Anyway... that's all changed... bio anything is now hard into mathematical modelling and big data... and so generates a demand for 'computerised'/computer-connected research instruments.

--
Roy Thistle

I am troubleshooting an older tek scope that has sweep issues and after doing a bunch of checks, am beginning to think the tunnel diode may be bad. The only way I know to test these is to remove them and put them in a fairly simple test ckt (voltage source, current meter, voltage divider before and load resistor) and watch the current as voltage is varied. Can also use a scope to see if it oscillates when the breakover voltage is exceeded.)

Is there a way to test them in place? (generally speaking). Also, if there is a way to test them out of the board that is different than what I described above, please let me know.

I just hate to stress the PCB with a lot of needless removal-reinsertion. I am well versed in the use of various soldering/unsoldering techniques as well as having the proper tools, I just don't like needlessly hacking on a board. Of course I wouldn't do this without doing a rather thorough ckt check and am fairly certain that the device is bad.

I do know not to test them with the typical diode test on a DMM as it will cause them to fail.
thanks
j

Many years ago we were at a second hand dealer that we knew well.

He came back from a house rather upset.

A Toolmaker had died & his family so admired the beautiful wooden tool boxes that they emptied all of his tooling - Moore & Wright etc into a dumpster & took it all to the recycling plant.

The toolboxes were beautiful timber ones with lots of drawers & there were over a dozen large ones that were originally totally full of tooling - all the tooling was in perfect condition & not a speck of rust.
... and all of it went as junk metal.

There was no way to salvage any of it.

The dealer had seen much of the tooling the year before but the family couldn't sell it as the elderly gentleman owner was still alive.


My father & I did electrical work at an old house.
Under the house was a huge room full of old crates, dynamite crates, food crates etc, turn of the century, piles of of old magazines in perfect condition because they had insecticide there, beautiful timber furniture, several gramophones...

We mentioned to the family that if they ever wished to sell any to let us know.

We went back several weeks later after the elderly occupant died to find all the furniture, the gramophones, all the documents etc all on one big bon fire.


Some people really don't think before they act.


Regards,
Brian.

I uploaded a pdf scan of my paper Operators manual 070-1402-00 to Tekwiki. A few pages were revised, up to Nov 1977.
Albert

I guess that it really does not matter how you get it done, just that you have the manual. Computers and networks do some crazy things from time to time. Good Luck with your repairs. Hoping to read of a successful repair in the near future.

--
Michael Lynch
Dardanelle, AR

It also helps quite a bit to carefully warm up the knob with a heat gun before pulling on it. This has been explained numerous times here.

Roy, that part was made by Tektronix.
Jeff

Hi everyone , I need help . My 661 has HV insulation breakdown in the power transformer and I need a suitable 6v transformer that can stand working at 3KV for the CRT heater . Here in the UK most sources for things like that have all but dried up . Does anyone in the group have one spare they would part with or know of a reliable source for a replacement . I would prefer as local a source as possible but obviously I would get one from anywhere .
Thanks in advance for any help with this .
Brian Skilton (UK)

Pre-retirement, I worked for a University in UK. Almost overnight, it
seemed, many of the research departments decided to 'go computer', and
there was a mass dumping of analog equipment, particularly by the Biophys /
Biomed groups. It was nothing unusual to see a pile of Tek 5111A s (with
5A22 plug-ins) just tossed in a skip (dumpster), along with Brush / Gould
pen recorders and DC amplifiers. Needless to say, these all soon found a
new home !!
There was also a 502A, which I just HAD to have, and a 565 with 3A3s,
again, just left out in the car-park with 'Scrap' chalked on them.
I also found a Philips DSO literally buried under a pile of broken-up lab
benches - I didn't realise this had a switching power supply until the RIFA
Stink Bomb Cap went off while I was testing it.
Also,[OT] when one of the libraries was refurbished, many thousands of
??/$$-worth of solid Mahogany bookshelves were tossed, but that's another
story. (Don't worry, they were spotted and rescued.)
Tim

They are basically a push/snap fit but unless you manage to pull exactly parallel to the shaft they have a tendency to break irreparably. Different people will proably recommend different tools but it comes down to levering both sides of the knob at the same time with similar screwdriver blades. I needed to remove about four or five and broke one so I am not the best person to offer advice on this.

Roger

does anyone know how the bigger knobs come off,ie the ones without allen grub screws?,tia.