Date   

Re: Tektronix Type 575 Transistor Curve Tracer - $75 (Syracuse)

Tam Hanna
 

Hello,

tried to get the guys email addy, but the Craigslist web site is not willing to let me in.


I would gladly pay for shipping. The 575 is the last of the Danaher curve tracers I still miss for my upgrade project.


Tam

--
With best regards
Tam Hanna
---

NEW: Enjoy electronics? Like seeing oscilloscopes get repaired? Please subscribe to my new YouTube channel -> http://www.youtube.com/user/MrTamhan


Re: 7854 vs 7D20

Daniel Koller
 

Dennis,
  Is that FFT program available to us?
  Dan

On Wednesday, December 13, 2017, 1:41:34 AM EST, 'Dennis Tillman' @Dennis_Tillman_W7pF [TekScopes] <TekScopes@...> wrote:

 
Hi Harvey and Cliff
,
The 7D20 is spec'd at 70MHz and 40MSamples/Sec. It is also GPIB compatible
so it is programmable.

The 7854 is also GPIB compatible but in addition it has its own built in
vector processing programming language. That was another thing that made the
7854 revolutionary when it came out. It was the first scope with its own
vector processing language. Unfortunately electronics engineers were
programming illiterate in those days and that feature actually discouraged
sales so Tek quietly stopped promoting it in their ads and in their
literature.

To this day I have not found more than a handful of 7854 programs in spite
of doing an exhaustive search of all of the EE magazines in the 1980s and
1990s. However, all that changed a few months ago when Holger Lubbin (a
member of TekScopes and a dedicated fan of the 7854) wrote what must be the
largest 7854 program ever written. It calculates the FFT of the signal
stored in the 7854 memory. Unfortunately the 7854 did not have floating
point math, a fast microprocessor, or lots of storage (3 things you need to
do an FFT) so it is not practical except as a proof of what the 7854 was
capable of.

Dennis Tillman W7PF

-----Original Message-----
Sent: Tuesday, December 12, 2017 8:25 PM
Subject: Re: [TekScopes] 7854 vs 7D20

On Wed, 13 Dec 2017 02:54:49 +0000, you wrote:

I already have a working 7854 and a good assortment of 7000 series
plug-ins. What would a 7D20 add that the 7854 cannot do or can only do
poorly or with difficulty? Is the 7D20 compatible with the 7854?

To the best of my knowlege, the 7D20 was used to add digital storage rather
specifically to the 7600 scopes, giving you a large screen digital scope. I
think that the digital bandwidth is about 20 Mhz or so.

With the additional processing in the 7854, the higher bandwidth, I can't
think of anything in particular the 7D20 would give you.

if you're looking for relative oddities, then a 7A42 logic plugin (4 trace,
dual width, somewhat of a logic analyzer, might be an idea.

Harvey

Cliff Carrie
------------------------------------
Posted by: Harvey White <madyn@...>
------------------------------------


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Re: Deane Kidd and the Metric System

Colin Herbert
 

Shortly after metrication of the UK currency came in, I saw a humorous article purporting to be issued by a Government Department which put forward the idea of metrication of time. The year would be re-defined as one thousand days and so “Superannuation” would become “Superkilodayvuation”. Before that point, the article seemed irritating, but believable.

Of course, didn’t the French come up with a similar notion during the Terror?

Colin.



From: TekScopes@... [mailto:TekScopes@...]
Sent: 13 December 2017 14:49
To: TekScopes@...
Subject: Re: [TekScopes] Deane Kidd and the Metric System





On 13/12/17 13:33, Adrian Nicol fenland787a@... [TekScopes] wrote:
Perhaps it helped with handling numbers to different bases in later life
As kids we were taught arithmetic in quite a few bases, including at least
2,3,4,6,8,10,12,14,16,20,22,112,1760,2040
Naturally we didn't realise we were doing that, we just did it.

But thank all the deities I never had to do that in anger as an adult.
Metrication was, and is, a godsend.





[Non-text portions of this message have been removed]


Tektronix Type 575 Transistor Curve Tracer - $75 (Syracuse)

pdusel
 

https://syracuse.craigslist.org/ele/d/tektronix-type-575-transistor/6421973174.html https://syracuse.craigslist.org/ele/d/tektronix-type-575-transistor/6421973174.html





"Tektronix Type 575 Transistor Curve Tracer. Functional when last used. Probably could use some new tubes and calibration. With light shield, some test sockets, and complete instruction manual including schematics. Closed the business, no longer need it."



As usual, no relationship, don't know any more etc...


Pete


Re: Deane Kidd and the Metric System

Tom Gardner
 

On 13/12/17 13:33, Adrian Nicol fenland787a@... [TekScopes] wrote:
Perhaps it helped with handling numbers to different bases in later life
As kids we were taught arithmetic in quite a few bases, including at least
2,3,4,6,8,10,12,14,16,20,22,112,1760,2040
Naturally we didn't realise we were doing that, we just did it.

But thank all the deities I never had to do that in anger as an adult.
Metrication was, and is, a godsend.


Re: Tek Knob Project Info -or- What Walter Actually Thinks

magnustoelle
 

Good Day,

Walter, I think I reflect most group member's thoughts when I am saying:

*Thank you for doing this and for the time you are spending on it!*

You may choose whatever dimensions or sorting schemes you'd want.
A simple indexed list of Tektronix part numbers in ascending order similar to the one on http://sphere.bc.ca/test/tek-parts/tek-knobs.html would be perfectly sufficient for me.

Closing comment from me: Tektronix knobs' dimensions were always imperial - enough said...

And thanks again, Walter.

Cheers,

Magnus

On 12/12/2017 23:39, @walter2 [TekScopes] wrote:

OK, enough already with the metric v. imperial saga.
Tek used Inches, all the knobs are spec'd in inches,
and the shafts they fit on are in inches. just get used to it, please.
I will clearly MARK in big text the knob number, diameter and shaft size,
you don't have to try and ferret it out from the image, the image is just to let you positively ID the part when looking at it. trust me when I say that is 100% doable.


there is exactly ZERO chance I will be doing anything showing metric values, so please, let's not dig any deeper into this total non-issue. the parts are not metric, so why even go there? the knobs and shafts do not change size, based on their location on earth. With only a few exceptions, what you really need to know is just "is that a 1/4" (big) or 1/8" (small) shaft". often identical looking knobs exist in both formats, so telling them apart is very handy.


what would have been very useful to me was some feedback on how to organize the index (or to provide some good photos), but since I got almost nothing useful on that topic, here is how I AM doing it, you can cheer or cry as you think is most appropriate.


first, why make this index? well, I have two situations I have to deal with often, I have loose knobs that are unknown as to part number or use, and I have equipment that needs a knob, and I need to know what that part is. Everybody buying, selling or trading knobs faces these exact problems all the time.


there is a third case, which is of zero value to me, which is I have a part number, and want to know what it is, for that, there is the Tek index. so please use it. No, I do not need any kind of sortable database (what the heck for?), I just need to be able to correctly ID parts, possibly find a workable sub, and put them away, or go get them.


in both these useful cases, I know something about the part, so it makes sense to group mechanically like parts together, which also makes substitutions much easier, and makes is simpler to distinguish between parts that are similar, but not identical. I have already found many parts similarities that were very useful to me, just in collecting the raw data. yay for serendipity.


so in terms of basic divisions, I have knobs that push on, and knobs with setscrews, knobs with integral shafts and specialty knobs (10 turn dials, for example, or SA parts). these get further divided by task (vertical, horizontal, round, fluted, etc.), and that makes for an index of very high utility, at least for me.
If I want a type of knob listed above, nothing else will really do, so why wade through many irrelevant entries, and how else could I see possible substitutions?


I have already put about 100 hours into this and photo preparation, so I am pretty far along. that's not to say I wouldn't respond favorably to good suggestions or offers to proof pages or look up data, though. needless to say, others are welcome to tackle this problem another way and with metric info. as they say, variety is the spice of life.


now you know,
all the best,
walter (walter2 -at- sphere.bc.ca)


Re: Deane Kidd and the Metric System

n4buq
 

The U.S. used to have a 1/8 dollar designation as a "bit". Two bits equals a quarter and is still sometimes heard amongst the older folks.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "geoffrey thomas geoffreythomas@... [TekScopes]" <TekScopes@...>
To: TekScopes@...
Sent: Wednesday, December 13, 2017 7:40:20 AM
Subject: Re: [TekScopes] Deane Kidd and the Metric System

Well yes, but you have 100 pennies to the dollar, same as us to the pound.
But we have other coins
too.
<snip>

sixpence or half-bob - also called a "tanner"
two shilling or two bob - also called a "florin"
<snip>

Geoff.


Re: Deane Kidd and the Metric System

James R. Bartlett
 

Don't forget the 2 and 6 pence, called a 1/2 Crown.
And the 5 bob called a Crown = 60 pence
Etc etc.

Jim
Ei2BB

On 13 December 2017 at 13:40, geoffrey thomas geoffreythomas@...
[TekScopes] <TekScopes@...> wrote:



Well yes, but you have 100 pennies to the dollar, same as us to the
pound. But we have other coins
too.
<snip>

sixpence or half-bob - also called a "tanner"
two shilling or two bob - also called a "florin"
<snip>

Geoff.



[Non-text portions of this message have been removed]


Re: Deane Kidd and the Metric System

Geoffrey Thomas
 

Well yes, but you have 100 pennies to the dollar, same as us to the pound. But we have other coins
too.
<snip>

sixpence or half-bob - also called a "tanner"
two shilling or two bob - also called a "florin"
<snip>

Geoff.


Re: Deane Kidd and the Metric System

Adrian Nicol
 

Hi Craig,You beat me to it! Some things were priced in Guineas (21 Shillings) too, in fact I think racehorses still are?

  I had a 'Saturday' job at Millets govt surplus store in Cambridge in those days, there were no calculators or cash registers that could add up so all that was handled in my head with no problem. Perhaps it helped with handling numbers to different bases in later life?
Adrian


On Wednesday, December 13, 2017 11:57 AM, "'Craig Sawyers' c.sawyers@... [TekScopes]" <TekScopes@...> wrote:


  > farthings (quarter penny - think about that for a moment; a 1/960th of a pound!), ha'penny (half
penny) penny thruppence (3 of them) sixpence or half-bob shilling or bob (12 pennies - living on
as the
5p coin) two shilling or two bob(24 pennies - lives on as the 10p coin) half crown (2 shillings
and 6
pence - or 1/8 pound)
Apologies - that totally failed to parse. Put that one down to Yahoo.

Craig

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Re: 7854 vs 7D20

 

On Wed, 13 Dec 2017 07:37:27 -0000, you wrote:

The 7854 uses a TMS9900 processor, with a maximum clock speed of 3MHz. Takes me back to 1981 in my
first paid job, designing video switching networks driven by that processor. Massive ceramic package
that needed a great amount of force to push into a turned pin socket.

...

Craig
Many people may have run across the TMS9900 in the TI-99/4 and
TI-99/4A home computers from Texas Instruments. I was surprised to
find it in the 7854 but immediately recognized it.


Re: Deane Kidd and the Metric System

Craig Sawyers <c.sawyers@...>
 

farthings (quarter penny - think about that for a moment; a 1/960th of a pound!), ha'penny (half
penny) penny thruppence (3 of them) sixpence or half-bob shilling or bob (12 pennies - living on
as the
5p coin) two shilling or two bob(24 pennies - lives on as the 10p coin) half crown (2 shillings
and 6
pence - or 1/8 pound)
Apologies - that totally failed to parse. Put that one down to Yahoo.

Craig


Re: Tek Knob Project "standard"

Colin Herbert
 

Thanks, Geoff. As it happens, I think I have seen “sawn” at some time in the past. It is probably the proper thing in timber-merchants rather than DIY stores. Thanks for the Welsh Birthday Greeting – my wife is Welsh and I spent a couple of years at Swansea University in the eighties.

Unfortunately, our house doesn’t have any log-fire facilities as it was converted to gas ages ago. However, the engineer is supposed to be coming today to replace the triple valve, so we might be warm soon.

Nadolig Llawen, Colin.



From: TekScopes@... [mailto:TekScopes@...]
Sent: 12 December 2017 21:00
To: TekScopes@...
Subject: Re: [TekScopes] Tek Knob Project "standard"





The hairy stuff is called "sawn" to differentiate it from planed.
Penblwydd hapus* from me too, get a log fire for all that hairy wood and
keep warm that way. :)

Geoff.

* Happy birthday.






[Non-text portions of this message have been removed]


Re: Deane Kidd and the Metric System

Craig Sawyers <c.sawyers@...>
 

Half dollars, quarters, and nickels divide dollars into halves, quarters, and twentieths.


------------------------------------
Posted by: David <@DWH>
------------------------------------
Well yes, but you have 100 pennies to the dollar, same as us to the pound. But we have other coins
too. The 2p(fiftieth), 5p (twentieth), 10p(tenth) 20p(fifth) and 50p(half) and �2(twice). There was
at one stage a 25p coin too (quarter). That doesn't make either you or us non-decimal for currency.
We just divide our decimal base currency whether US dollars or pounds sterling into convenient
chunks.

At least it is a bloody sight easier than our previous system, where a pound was divided into 240
pennies. In fact we had

farthings (quarter penny - think about that for a moment; a 1/960th of a pound!),
ha'penny (half penny)
penny
thruppence (3 of them)
sixpence or half-bob
shilling or bob (12 pennies - living on as the 5p coin)
two shilling or two bob(24 pennies - lives on as the 10p coin)
half crown (2 shillings and 6 pence - or 1/8 pound)

Even for those like me who were brought up with that system until age 15, it was complete madness.
Doing mental arithmetic with it was a nightmare.

Craig


Re: 7854 vs 7D20

 

Unless a 7B87 timebase is used, the 7854 always operates in random
sampling mode. The only difference between it and a sampling
oscilloscope is the linear elements like amplifiers and attenuators
before the samplers. I say samplers because sampling oscilloscopes
and the 7854 sample both the vertical input and the horizontal sweep
unlike digital storage oscilloscopes like the 7D20 which sample only
the vertical signal and rely on a digital timebase. One later
oscilloscope, the 2252, works the same way as the 7854.

When a 7B87 timebase is used, then the 7854 operates like a digital
storage oscilloscope but its maximum sampling rate is pretty low at
like 500 ksamples/second.

On Tue, 12 Dec 2017 23:03:24 -0500, you wrote:

The 7D20, and the 7854 handle digitization in very different
ways. The 7D20 uses a CCD to store the analog waveform, and
then reads it out slowly into a slow ADC to digitize the waveform.
At sufficiently slow speeds, it directly digitizes the waveform
using the ADC... below 50KHz, I think.

The 7854 goes directly to the ADC for slow speeds, below 500KHz,
I think, but for higher frequencies, it behaves as a sampling
scope, taking samples in random positions after the trigger,
until the entire waveform has been sampled.

I use the 7D20 a lot more often for digital duty than I do the
7854.

-Chuck Harris


Re: Tek CRTs may not be metric after all

 

Well, Tektronix specified all of their graticule divisions in metric
units and I suspect this is because the CRT physics calculations would
be more easily done in metric as well. I only used CRT graticules as
an example where Tektronix did use the metric system in their
specifications and was obviously aware of it which has nothing to do
with practical manufacturing in the US which would lead to imperial
units for the CRT envelope.

I am glad I looked up the 7603 before I posted because I thought it
was an exception with 0.5 inch divisions but it was 1.22 centimeters
instead of 1.27.

On Tue, 12 Dec 2017 18:43:12 -0800, you wrote:

Hi David,

I don't think the 7000 series graticules are DESIGNED as metric at all. The
same may be true for the older scopes as well. I think graticule dimensions
have more to do with the size of the CRT bulb and that is influenced by how
much performance can be squeezed out of the design of the CRT itself.

The biggest possible area is used on the front of the CRT after all the
other factors determine the size of the bulb. At that point the measurement
is reported in centimeters probably because of some historical reason
(doesn't the optical industry prefer the metric system?).

For the 7000 series alone there are 5 different graticule measurements:
1.22cm, 1.0cm, 0.96cm, 0.85cm and one more I don't recall at the moment.

Dennis Tillman W7PF


Re: Deane Kidd and the Metric System

 

On Wed, 13 Dec 2017 07:13:05 -0000, you wrote:

...

That is a very interesting story Dennis. It must have come as a shock when you touched Deane's
nerve. But oddly you have had metric currency for a whole lot longer than we have in the UK.

...

Craig
Half dollars, quarters, and nickels divide dollars into halves,
quarters, and twentieths.


Re: 7L14 "Save A" function (Solved?)

NigelP
 

Before anybody expends any brain power on this one I think it's sorted.

I opened up the whole SA unit and peered at the A88 digital storage board and poked around a (little) bit. There are some inter-board connectors on there and the one connection that transferred the Save A line looked a little wonky so I poked it and straightened it, didn't find any else suspect visually so put it all back together and, hey presto, it's working properly :).

I have to assume a dodgy connection caused the problem, not really surprising considering the age of the unit. Somewhat relieved because changing the memory chip looked like a non-starter (48 pins and no socket).

Nigel


Re: Tek CRTs may not be metric after all

Craig Sawyers <c.sawyers@...>
 

0.85 cm/div. to be exact. In the case of the 7104 the limiting factor was not the CRT bandwidth
since
the 3dB point of the vertical deflection plates is above 3GHz. I believe the limiting factor was the
size
that the company doing the MCPs could make them. No one had ever asked for such a large MCP
before Tek came along.

Dennis Tillman W7PF
It was initially Mullard in the UK, who had experience of using them in military image intensifiers. I
talked to the guy who did the development around six or seven years ago, when he was working for
Photonis in Brive, France. He said that making a plate of that size was a real challenge, particularly
since the channels have a bias angle of 20-odd degrees. He developed the X-RAY telescope plates for
the Bepi Colombo mission to Mercury that I was Project Manager for. So I have a pretty good grip on
how the Tek MCP's were made, and what the likely piece price was for the plate alone.

You might remember the history from then on Dennis; I believe that manufacture was moved to a US
company fairly soon after.

Craig


Re: 7854 vs 7D20

Craig Sawyers <c.sawyers@...>
 

Unfortunately the 7854 did not have floating point math, a fast microprocessor, or lots of storage
(3
things you need to do an FFT) so it is not practical except as a proof of what the 7854 was
capable of.

Dennis Tillman W7PF
The 7854 uses a TMS9900 processor, with a maximum clock speed of 3MHz. Takes me back to 1981 in my
first paid job, designing video switching networks driven by that processor. Massive ceramic package
that needed a great amount of force to push into a turned pin socket.

Because it was so sluggish, that processor design worked right off. I put all the bodge logic into a
PAL. The one gotcha is that Texas had different division for processors and memories. And each of
them labelled their buses the opposite way. Bastards. One has A0/D0 as LSB and the other had them as
MSB - so there was a massive bit scramble on the buses. While I was moaning about my not noticing it
and beating my chest, and just about to run at the circuit board with a knife and wirewrip, our
brain-on-a-stick software guy said "Don't do anything - I'll just do a bit scramble in software.
It'll be a security feature!". I could have kissed him; well not really, but you get the idea that I
was a relieved guy.

That software fella was of course a bit weird. You could never catch him doing any work. He was
either drinking coffee, was at the pub, or eating smelly food at his desk. But magically 100 lines
of bug-free and beautifully commented code appeared at the end of each day. Blow the compiled
finished code into a PROM and it would work right off. Damndest thing. I only once accused him that
his code didn't work. He asked what the symptom was, and immediately without noticeable pause and
looking over his pint of beer said "bit 4 of the third BCD switch from the left - the wire has
fallen off". He was of course absolutely right.

Craig