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In my post "In Defense of the 7A19" on 5/30/2020 1:45PM I mentioned several
ways HP upstaged Tektronix' introduction of the 7000 series at WESCON in San
Francisco in 1969. One of the more embarrassing demonstrations showed their
new lab scope continuously triggering on a signal that was swept through the
250MHz bandwidth of the scope without missing a trigger or needing
adjustment. By contrast the 7000 time base required constant fiddling with
the trigger controls to do the same test.

Several members never gave triggering a thought until I mentioned this since
it seemed so obvious and simple to do. They were puzzled by how HP was able
to do this. Stable triggering is everywhere now but that was not always the
case. Even after its importance was recognized and trigger circuits were an
additional feature of most scopes there was a constant need for improvement
and additional trigger capabilities necessary to meet the changing needs of
the engineers who were being asked to measure more complex signals all the
time.

Historical Background
* There was a time when the need for triggering was not obvious. After the
war one of the important ways Tektronix scopes differed from many other
scopes was because they had triggering, and because their triggering was
very good. Up until then most scopes had a free running sweep. This required
the user to synchronize the scope's sweep to the signal by adjusting the
sweep speed until the sweep circuit could be pulled into synchronism with
the incoming signal.

* Tektronix was founded to make oscilloscopes that were measurement
instruments. There is no way to measure time or sweep speed with a free
running sweep scope. Tektronix knew how important stable triggering was to
make measurements with a scope.

* During the war the development of RADAR advanced very rapidly because it
gave the Allies a strategic advantage. Early radar displays used very simple
CRTs to show radar echoes as vertical blips on a horizontal trace on a CRT.
The distance along the horizontal trace from the origin indicated how far
away the source of the echo (enemy) was. The taller the blip the more
reflective the enemy object was. Sometimes there were many blips bunched
together into one bigger blip. It would be highly desirable to magnify that
large blip to separate it into individual blips. That is the origin of
today's delayed sweep. This gave the radar operator the ability to select a
particular portion of the trace and magnify it to examine it more closely.
Some scope users may never use the delayed sweep their scope has. A few of
you know how and when to use it. It is the electronic equivalent of an
inspection microscope with incredible range of magnification you can use to
peer into any part of a signal to see what is going on at that instant. So
much information in a waveform is too small to see until you switch to
delayed sweep to see all the detail and start to ask what is causing it.

Here is a simple experiment that will show you a tiny but important glitch
in a common waveform that causes a lot of problems. It requires only 3
parts: a small power transformer (115V primary and a 24V or 12V secondary);
a full wave bridge, or a full wave rectifier, or a half wave rectifier; a
power resistor from 200 ohms to 2,000 ohms than can dissipate the heat.
Connect your rectifier to the transformer secondary then connect the power
resistor between the + and - leads of the rectifier you are using. Clip a
probe across the resistor and set the trigger source to Line. Set the sweep
speed to 2mSec/Div to display one complete AC cycle. There will be one
complete waveform on the CRT. Enable the delayed sweep and set the sweep
speed to 20uSec/Div. Use the Delay Time Mult dial to scroll across the
waveform until any half sinewave reaches ground (0V). Increase the vertical
sensitivity to 20mV/Div. At the point where the rectified waveform reaches
zero you will see it continues going into negative territory. You will see a
small spike that goes anywhere from 50mV to several hundred millivolts below
zero. Increase the delay sweep speed until the spike is a few graticule
divisions wide at its half amplitude point. Measure the width of the pulse
in microseconds. Divide 35 by the microseconds you measured. My pulse was
50mV high and its width in microseconds was 10. 35 / 10 = 3.5Mhz. That pulse
will generate electrical noise from 60Hz up 3.5MHz and you will distribute
that energy to everything connected to your power supply. It is so small and
short most people don't even know it's there. They have even less idea how
much electrical noise (static) that little spike can cause.

Back to HP and their wonderful triggering. It is explained on page 17 of the
January 1970 issue (Volume 21, Number 5) of the HP Journal in the "A Fast
Time Base for a High-Frequency Oscilloscope" article by William Mordan. This
entire issue is devoted to the new scope. It is in the HP Archive thanks to
one of our members


There are two coincidences in this HP Journal:
Coincidence #1) The very last name on the very last line on the very last
page of the HP Journal is Maridel Jordan. The Journal was a pet project of
David Packard and he would occasionally stop by to see what Maridel was
working on and to make suggestions. Maridel later married and the couple
moved to Bellevue where Larry, her husband, works. 30 years ago our daughter
and their daughter attend the same elementary school and eventually the four
us - Larry, Maridel, Marian ("She who must be obeyed"), and I form Ridesoft,
LLC. That is the origin of my email address.

Coincidence #2) Scroll past the end of the Journal to the next page where it
explains the HP Archive (www.hparchive.com <> ) made
it possible for you to read this issue. The Archive's On-line curator is our
own John Miles KE5FX and a friend of mine. Several years ago, if I remember
this correctly, he mentioned to me there were HP Journal issues that were
needed to fill in gaps in the archive. Since I had about 20 years' of them I
urged him to take whichever ones he needed.

Dennis Tillman W7pF

This is a bit off-topic but the low proportion of women in engineering in
general has made professional societies to which I belong lexaminet the
question and have efforts at attracting more women. The IEEE membership is
about 8% women and 92% men. The International Society for Optics and
Photonics (SPIE) is a bit more balanced; in the US 20% of members are women
and 80% men (based on the SPIE annual salary survey which is sent out to
members). The Society for Imaging Informatics in Medicine (SIIM) has a
percentage of women a bit higher than SPIE, though I have not seen the 2020
demographics (the annual meeting will be held as a virtual meeting later
this month).

I am a member of these organizations and I can tell you one thing I have
noticed. For SPIE and SIIM which tend to have engineers working on end-user
applications and research, the women I know in these organizations almost
all spent some of their undergraduate years in the usual "circuits and
systems" sorts of courses. Building analog circuits (filters, amplifiers,
etc) and digital ones. When they got to computer systems, it took hold of
many of them and they shifted from building logic circuits to writing code.
Some of them were pretty hard core logic designers "programming on the bare
metal" as is said. They routinely implemented image processing stuff in
FPLAs. Others code at a high level and write systems software (my wife, now
retired, is one of those - though she never took an EE course she wrote
very good code, far more efficient than my tendency to write brute-force
code.

A few biomed engineers in the group of women also - mostly with PhDs in
bioengineering or biophysics. In their early years, they did work in EE
applications, generally building servo systems for biofeedback control or
combining circuitry for low-level signal detection and amplification with
computer code for noise reduction and signal restoration. In common? They
started out like many EEs but tended to move into more direct applications
fields.

Some of you may have an opinion, but one I have heard from educators is
that, in the US, an unfortunately common thing is that women do well in
math up to a point (usually after algebra and geometry) and then they lose
interest. I certainly saw this in high school, though this was in the '60s
and I don't know if is still true.

Steve H.



On Sat, Jun 6, 2020 at 11:13 PM John Ferguson via groups.io <jferg977=
[email protected]> wrote:

Look up Josephine (Josie) Webb. EE graduate of Purdue circa 1940.
She's still with us at 100. Dad worked with her at Westinghouse in East
Pittsburgh during the war. She was regarded as the sharpest engineer her
section at the time.

But that was power engineering not RF.

On 6/6/20 10:26 PM, John Griessen wrote:

On 6/6/20 8:09 PM, lilacbarn wrote:

What is it about electrical/electronic engineering that turns women

off that as a career?

The Civils and Mechanicals seem to do far better at attracting women

into the profession.

Geoff.

I saw a similar ratio in small company chip design in the early 90's.
One woman circuit design engineer that was ex TI in a group of ten.
When I was looking for work locally, not wanting to move in the 2000's
I tried hanging out with the civil engineers with the idea of getting
a PE license, but didn't connect really well with any of them. They
seemed to wear more formal clothes, not be excited about any silicon
valley news, happy to just use their "license to charge" for govt.
required services and go along living their lives in comfort with
ample money to spend on meeting fees, dinners, etc. Women seem to put
other than self as top priority more, often prioritizing not moving,
not upsetting their children's lives more, and that could explain how
CE has so many. About mechanical, who knows?

On Fri, Jun 5, 2020 at 03:43 PM, Dennis Tillman W7pF wrote:

Israel Banini, chose a site devoted to health news

Hi Dennis, Hi All:
If there is an Israel Banini, by his pen, Israel is an expert on catamarans, sewing machines, Legionnaire's disease and other quite numerous and diverse topics: quite the renaissance man!
More likely, IMO, these are hijacked articles to act as click bait, to draw viewers to that (his?) website... and increase the ad revenue.
One is not suppose to read the article(s) but rather click on the ad's... I mean... who doesn't want to know how to tell if they are going to have a heart attack, by looking at their feet.
But back to Tek... since I am guessing, most of us are analog scope fans here... shouldn't we have a Tek digital, versus Tek analog thread on the forum... or an update on the contents of others that have been started about this?
Best regards and wishes all.
Roy

Look up Josephine (Josie) Webb.? EE graduate of Purdue circa 1940.? She's still with us at 100. Dad worked with her at Westinghouse in East Pittsburgh during the war. She was regarded as the sharpest engineer her section at the time.

But that was power engineering not RF.

On Sat, Jun 6, 2020 at 10:10 AM, Ed Breya wrote:

I don't know how the GPIB option is connected internally

Hi Ed, Hi Lawrence:
It's probably detailed in some thread on the forum already... but page 5-17 of the Tektronix (1990, rev. 1991)24X5B12467B Options Service(Serial Number B050000 and above, 070-6864-02) manual covers the removal. (power cable, internal bus cable, led cable, and cable to the GPIB connector.)

That manual is available on tekwiki at


But unless you plan to take the scope with you (and some of would like to, I know)... posterity may thank you for leaving the GPIB option in... and if you sell it in the future, you may than you for leaving it in.

Best regards and wishes.
Roy

On 6/6/20 8:09 PM, lilacbarn wrote:

What is it about electrical/electronic engineering that turns women off that as a career?
The Civils and Mechanicals seem to do far better at attracting women into the profession.
Geoff.

I saw a similar ratio in small company chip design in the early 90's. One woman circuit design engineer that was ex TI in a group of ten. When I was looking for work locally, not wanting to move in the 2000's I tried hanging out with the civil engineers with the idea of getting a PE license, but didn't connect really well with any of them. They seemed to wear more formal clothes, not be excited about any silicon valley news, happy to just use their "license to charge" for govt. required services and go along living their lives in comfort with ample money to spend on meeting fees, dinners, etc. Women seem to put other than self as top priority more, often prioritizing not moving, not upsetting their children's lives more, and that could explain how CE has so many. About mechanical, who knows?

On 6/6/20 7:42 PM, DaveH52 wrote:

The A5 and the mainboard are connected cordwood style.

Are there pins and contacts like in 7xxx scopes? If so, just pull them apart.

Ha, Tony, I've copied code from that EDN magazine article myself. I'm running into an issue with Python not finding the numpy, pandas, and visa libraries. I guess that's what they're called, libraries. Will dig into it more this weekend. Just barely getting started with Python and GPIB myself. It's sure a learning experience. Good luck!

Jim Ford

I have a Tek 284 that I am working on what is mostly working there is just some issues with the pulser output of course. I finally worked up the nerve tonight to test the Diode it has been on the shelf for a while. I knew these didoes were fragile and are very expensive to replace. I found them… for $250.00 each diode. So the way I have things set up, a curve tracer set to DC and very sensitive measurements. I have the collector going out to a Keithly 6500 to watch the current. As I turn up the collector I get current flow in to the diode. At about 9mA there is a LARGE increase in current. But NOT a short. If I dial down the collector it looks like the diode recovers. RIGHT about 9 mA I can get it to flutter between the 2 current readings. So if I am reading the instruments correctly is this tunnel diode good? I am thinking it is but I am very new to tunnel diodes. I know I am in the deep end of the pool with this one but confirming the diode would be great news to getting this 284 up and running. I can put up a short video if it will make more scene

Eric

You are absolutely right Dennis.
In my days managing a testing lab there were few women in the lab.
But those that we did have were excellent with the equipment they needed to do their Jobs.
I only had one female EE doing electromagnetic engineering and test.
I had one Chemist doing material science analysis who was a whiz with an electron microscope and mass spectrometry,
One Mechanical engineer doing heat flow and thermal analysis that knew her stuff on wind tunnels, thermal cameras and high speed video.
I had a Physisist somewhere in the department, but cannot remember what she did.
That is not many in a lab of 40 or so. We had no women in the test technician category.
That was in the 80's, so I really do hope the ratio has improved since I retired many years ago.
I know when I was interviewing people there were very few female applicants for the EE positions,
but it was better in the software departments of our company.

What is it about electrical/electronic engineering that turns women off that as a career?
The Civils and Mechanicals seem to do far better at attracting women into the profession.
Geoff.

Monty, thank you for the info - I did download both the article and Github
- and when I can, I'll try to make it work.
Have a great weekend!
Tony

So I've been able to probe a little in the HV section, some of the transistors that I could get to ohm out OK.
BUT! Hidden underneath the A5 AUX board there are some scorched components on the mainboard.
The A5 and the mainboard are connected cordwood style.
How on earth can they be separated so I can get to the components on the mainboard?
Dave - AC2GL

My mistake. If it has a head with an + on it I call it a phillips, but you are correct they're really pozidrive.

Tony,

I wish I could edit my last post.

To run any program on the 4041 that is not already saved on a tape - you need the 4041 Programming ROM option in the 4041. You would also need the Plotting Option ROM to make an image from a waveform captured by the 7D20.

To control the 4041, you either need a working tape with a AUTOLD file that changes the 4041 console from the keyboard to the COMM port, OR you need to connect a PC to the keyboard connector with a USB to TTL serial adapter - and you need to perform the resistor mod I described in an earlier post.

Interfacing to the keyboard connector can only provide instructions to the 4041, so you could use the two instructions provided in one of my earlier post to change the console to the COMM port. Then you would use a different adapter: USB to RS-232 to connect the PC to the COMM port. At this point you can send commands to the 4041 including programs, and the console output will be sent to the PC and could be captured in a file.

That file on the PC could then be sent to the Tektronix terminal emulator - if it was the program in the 7D20 for example.

Monty

Tony,

The 7D20 Instrument Interfacing Guide has program listings for the 4041 and 4052A that put or get waveforms from the 7D20.

I don't know how you would use the 2465 to trigger the 7D20 to digitize a waveform, but assuming that could be done, a 4041 with the Programming Option ROMs and Plotter Option ROMs would be able to load the program in that guide from a PC connected to the COMM port.

You could connect the PC to the front panel keyboard connector with two jumper wires to a USB to TTL serial adapter - after you perform the resistor mod to the Front Panel interface board in the 4041 - in one of my previous messages in this thread.

The 4041 Plotter Option ROMs would allow you to connect to a Tektronix 4662 or 4663 plotter and provide a hard copy plot of the waveform (see page 83 in the 4041 GPIB programming guide for an example plot to a Tek graphics terminal - similar program would plot the waveform on a plotter.

There are programs for the PC that could emulate the Tektronix terminal - so you wouldn't need the plotter. You would need a USB to RS-232 interface plugged into the 4041 COMM port to receive the data on the PC. Then you would load the data file into the Tektronix terminal emulator program from this site:

Then you could snapshot the graphics screen on the PC and send it to any PC printer.

Hope that helps.

Monty

Thank you very much for your reply.
I do have DMM 2465 with option 10 GPIB - I should state that earlier, sorry.
I do have the Tektronix P6407 Word Recognizer Probe with the 2 rows of
attachable probes...
But in one of today's responses, I was assured that I can't connect it to a
computer - so I'm confused now.
I was hoping to use Python or something like that... :

I know that they do not talk about my scope, or any analog scope, but there
are very smart people out there!
It wouldn't surprise me if there is something that works with one of my
rear ports..

I have a programmer and probably have EPROMs I can donate to the cause if
there are dumps available I can use. My scope is a 2465B, so I can’t just
clone ones from that.

On Sat, Jun 6, 2020 at 17:08 <trogg58@...> wrote:

Hi, Andy, thanks for your reply, yes I do have the manual and have waded
through the self test routines and blinky Leds, or lack of! ... they only
come on and stay on so i have looked at the p.o.s.t order, waveforms and
flowcharts, I think i have possibly.... narrowed it down to the the 2
eeproms on the A5 Control board, U2378 and U2162. In fact I can remove both
of these and it makes no difference to where the bootup sticks or the whats
on the CRT display. I am beginning to wonder if ... while I was waiting for
the Caps to arrive, I put the scope back on the shelf in the garage
(without the outer sleeve), now most unusually it has been quite sunny the
last couple of weeks here in the UK and i'm wondering if the UV erasable
EPROMs have been erased to some degree..... I am trying to get my hands on
a copier so i can try and....
a) attempt to checksum and or
b) recopy, if i can find the hex/bin files
I have added another couple of piccys to the "John 2465 Project" photos.
Just a quick note, I have also added a close up pic of the leds, difficult
to see which ones are on or is it bleed over ?

Thanks again




--

Andy

Hi, Andy, thanks for your reply, yes I do have the manual and have waded through the self test routines and blinky Leds, or lack of! ... they only come on and stay on so i have looked at the p.o.s.t order, waveforms and flowcharts, I think i have possibly.... narrowed it down to the the 2 eeproms on the A5 Control board, U2378 and U2162. In fact I can remove both of these and it makes no difference to where the bootup sticks or the whats on the CRT display. I am beginning to wonder if ... while I was waiting for the Caps to arrive, I put the scope back on the shelf in the garage (without the outer sleeve), now most unusually it has been quite sunny the last couple of weeks here in the UK and i'm wondering if the UV erasable EPROMs have been erased to some degree..... I am trying to get my hands on a copier so i can try and....
a) attempt to checksum and or
b) recopy, if i can find the hex/bin files
I have added another couple of piccys to the "John 2465 Project" photos.
Just a quick note, I have also added a close up pic of the leds, difficult to see which ones are on or is it bleed over ?

Thanks again

On Sat, Jun 6, 2020 at 05:09 PM, Tim Phillips wrote:

I read somewhere (can't find it now ) that there is a mod to enable a CA
plugin to use the A / B alternate sweep feature of the 547 scope. Anyone
know how it was done?
Hakan ? (I looked in your pages of opts & mods)

That would be 040-0391-01 for CA. Couldn't find anything similar on 1A4.
Intructions now at
/H?kan

Hi Dennis,

You are right. That AppNote goes far beyond fundamentals into specifics of those digital scopes that don't apply to our scopes.
I will read through it only for curiosity. But won't you over the years start seeing these digital scopes at bottom prices on ebay, and have some interest in expanding into them?
For me, this will be passed my time and I have too much love for CRTs plus what is around them, and no opportunities to need anything more.

About her working with instruments with her unbuttoned cuffs, she should have plenty of opportunities to learn better by getting them into the beet salad or tomato sup she prepares in the kitchen.

Ernesto