Date   

Re: Low cost Scope-Mobile alternatives?

Al Holt
 

On Tue, Jul 10, 2018 at 05:19 pm, Michael A. Terrell wrote:

How about a cheap welding cart, or make a copy of the design from the online manual?
https://www.harborfreight.com/welding-cart-69340.html
The welding cart is nice in it has a sloping front, but the one I looked at Harbor Freight just doesn't have the depth to handle the 7603 from what I could tell.

--Al


Re: Low cost Scope-Mobile alternatives?

Michael A. Terrell
 

I have a bunch of these in both the shop, and in the house. They are sturdy enough, but a piece of plywood under the bottom shelf makes them even stronger.

<https://www.harborfreight.com/16-inch-x-30-inch-steel-service-cart-5107.html>
Michael A. Terrell

-----Original Message-----
From: "Ed Breya via Groups.Io" <edbreya=yahoo.com@groups.io>

Haha - I just looked at those Harbor Freight ones someone linked. That's the kind I was picturing, whether plastic or metal. Some are kind of spendy, but if you look at the coupons, there's a 3-shelf steel one for $40 on sale (regular $50). There's a 2-shelf steel one for $38 regular, so you could use your 20% off coupon to get it around $30. The 3-shelf will be much sturdier, however. The best thing to do with HF stuff is look at it in person to be sure it's of sufficient quality and function. In this price range, there's not much point to making your own.


Re: Low cost Scope-Mobile alternatives?

Michael A. Terrell
 

How about a cheap welding cart, or make a copy of the design from the online manual?

https://www.harborfreight.com/welding-cart-69340.html

Michael A. Terrell

-----Original Message-----
From: "Ed Breya via Groups.Io" <edbreya=yahoo.com@groups.io>
Sent: Jul 10, 2018 7:58 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Low cost Scope-Mobile alternatives?

Are the real scope carts all that expensive? I've bought a few over recent years at flea markets and junk stores for around $10-25 typical. I was under the impression that the carts aren't in big demand anymore, and those I've gotten were sitting in stores for months, or still around near the end of a flea market, with no takers. The problem may be in the timing - when you need one, it's hard to find a deal. That's why I just get one whenever a good deal shows up, and worry about commissioning it later. I've got two uncommitted ones in stock right now, that will eventually be scoped up, but are storage shelves until then.

You should be able to fairly easily come up with a bought or homemade rig that will perform the needed function. Chances are that shortly thereafter, a real one will show up for $20. Oh well.

I hate those wire-frame shelving and cart systems, so would never recommend them for anything. I think a simple utility cart with casters and a solid tray top is the way to go, in new or used form. It's a very basic piece of equipment, so there should be plenty to choose from. You may even want to look at outdoor garden carts - some are quite sturdy.

Another semi-homemade option is to use the base cabinet of an old junked propane BBQ. I have made a number of benches and carts from these and almost anything else that rolls and is sturdy enough. You just have to come up with a wood top for it.


Re: Low cost Scope-Mobile alternatives?

Ed Breya
 

Haha - I just looked at those Harbor Freight ones someone linked. That's the kind I was picturing, whether plastic or metal. Some are kind of spendy, but if you look at the coupons, there's a 3-shelf steel one for $40 on sale (regular $50). There's a 2-shelf steel one for $38 regular, so you could use your 20% off coupon to get it around $30. The 3-shelf will be much sturdier, however. The best thing to do with HF stuff is look at it in person to be sure it's of sufficient quality and function. In this price range, there's not much point to making your own.

Ed


Re: OT: Scopes and other electronics on "The Outer Limits"

Michael A. Terrell
 

Teaching a chimpanzee to use a meter is easy, but have you ever see one than can solder worth a damn? ;-)


Michael A. Terrell

-----Original Message-----
From: Albert LaFrance <albert.lafrance@...>

I've been watching some episodes of the outstanding US science-fiction TV
series "The Outer Limits", which aired from 1963-1965 (two seasons). The
settings of many episodes prominently feature electronic equipment,
typically in a scientific laboratory, military command post, space mission
control center, or a spacecraft.
A lot of the props were from local surplus stores. Even if it had been marked, it wouldn't have made sense.

Despite the fact that the show's opening title sequence begins with what is
probably best-known oscilloscope trace in history
(https://www.youtube.com/watch?v=FCcdr4O-3gE), I haven't seen a lot of
scopes in the episodes themselves, and the few that have appeared weren't
operating. A DuMont shows up from time to time, just sitting on a counter
or console as an afterthought. You'd think they'd at least be rigged up to
display the ever-popular Lissajous figures, but the series was pretty
low-budget.



One episode showed, in the background, a cart-mounted scope which had the
general form and panel layout of a Tek 500 series, but with a sort of white
cowling around the top and sides of the front panel. In another, there was
a rack-mounted 5-inch scope with a dark gray/green panel. I don't know what
brand either scope was.



In general, the electronics were a mix of real contemporary equipment and
stuff that was probably purpose-built as props. The real equipment
sometimes included those big multi-track analog tape recorders and vertical
pen plotters that were so popular in the early years of aerospace
development. The "prop" equipment was generally panels of meters, toggle
switches, pots/rotary switches and indicator lights; the meters and lights
were usually non-operational unless they had some significance in the plot.
A lot of them were in 19-inch racks or bench-type consoles.



A striking feature of these "prop" panels was the lack of labeling on any of
the devices unless, again, a particular device had a role in the story (e.g.
the radiation meter on an out-of-control reactor). But then, I guess a
scientist who's smart enough to invent a time machine or inter-dimensional
portal should be able to remember what switch does what.



Another electronics tidbit from the series: in one episode, a scientist had
developed a way to rapidly advance an individual primate's (including
human's) evolution, based on the premise that an organism's future form is
already encoded in its DNA and can brought out by the use of a machine built
for that task. To show a visitor how effective this technique was, the
scientist pointed to one of his successes - a chimpanzee seated at a bench
in a corner of the lab, quite convincingly using a VOM to troubleshoot some
piece of vacuum-tube electronics!


Re: Low cost Scope-Mobile alternatives?

Pete Lancashire
 

In some parts of the country scope equipment or any type of cart seem to be
rare birds. the Portland Oregon area is one of them.

I'd love to see the one build out of plywood I have a friend with the
Woodshop that could duplicate it or come up with something close.



On Tue, Jul 10, 2018, 4:58 PM Ed Breya via Groups.Io <edbreya=
yahoo.com@groups.io> wrote:

Are the real scope carts all that expensive? I've bought a few over recent
years at flea markets and junk stores for around $10-25 typical. I was
under the impression that the carts aren't in big demand anymore, and those
I've gotten were sitting in stores for months, or still around near the end
of a flea market, with no takers. The problem may be in the timing - when
you need one, it's hard to find a deal. That's why I just get one whenever
a good deal shows up, and worry about commissioning it later. I've got two
uncommitted ones in stock right now, that will eventually be scoped up, but
are storage shelves until then.

You should be able to fairly easily come up with a bought or homemade rig
that will perform the needed function. Chances are that shortly thereafter,
a real one will show up for $20. Oh well.

I hate those wire-frame shelving and cart systems, so would never
recommend them for anything. I think a simple utility cart with casters and
a solid tray top is the way to go, in new or used form. It's a very basic
piece of equipment, so there should be plenty to choose from. You may even
want to look at outdoor garden carts - some are quite sturdy.

Another semi-homemade option is to use the base cabinet of an old junked
propane BBQ. I have made a number of benches and carts from these and
almost anything else that rolls and is sturdy enough. You just have to come
up with a wood top for it.

Ed





Re: Low cost Scope-Mobile alternatives?

Ed Breya
 

Are the real scope carts all that expensive? I've bought a few over recent years at flea markets and junk stores for around $10-25 typical. I was under the impression that the carts aren't in big demand anymore, and those I've gotten were sitting in stores for months, or still around near the end of a flea market, with no takers. The problem may be in the timing - when you need one, it's hard to find a deal. That's why I just get one whenever a good deal shows up, and worry about commissioning it later. I've got two uncommitted ones in stock right now, that will eventually be scoped up, but are storage shelves until then.

You should be able to fairly easily come up with a bought or homemade rig that will perform the needed function. Chances are that shortly thereafter, a real one will show up for $20. Oh well.

I hate those wire-frame shelving and cart systems, so would never recommend them for anything. I think a simple utility cart with casters and a solid tray top is the way to go, in new or used form. It's a very basic piece of equipment, so there should be plenty to choose from. You may even want to look at outdoor garden carts - some are quite sturdy.

Another semi-homemade option is to use the base cabinet of an old junked propane BBQ. I have made a number of benches and carts from these and almost anything else that rolls and is sturdy enough. You just have to come up with a wood top for it.

Ed


OT: Scopes and other electronics on "The Outer Limits"

Albert LaFrance
 

I've been watching some episodes of the outstanding US science-fiction TV
series "The Outer Limits", which aired from 1963-1965 (two seasons). The
settings of many episodes prominently feature electronic equipment,
typically in a scientific laboratory, military command post, space mission
control center, or a spacecraft.



Despite the fact that the show's opening title sequence begins with what is
probably best-known oscilloscope trace in history
(https://www.youtube.com/watch?v=FCcdr4O-3gE), I haven't seen a lot of
scopes in the episodes themselves, and the few that have appeared weren't
operating. A DuMont shows up from time to time, just sitting on a counter
or console as an afterthought. You'd think they'd at least be rigged up to
display the ever-popular Lissajous figures, but the series was pretty
low-budget.



One episode showed, in the background, a cart-mounted scope which had the
general form and panel layout of a Tek 500 series, but with a sort of white
cowling around the top and sides of the front panel. In another, there was
a rack-mounted 5-inch scope with a dark gray/green panel. I don't know what
brand either scope was.



In general, the electronics were a mix of real contemporary equipment and
stuff that was probably purpose-built as props. The real equipment
sometimes included those big multi-track analog tape recorders and vertical
pen plotters that were so popular in the early years of aerospace
development. The "prop" equipment was generally panels of meters, toggle
switches, pots/rotary switches and indicator lights; the meters and lights
were usually non-operational unless they had some significance in the plot.
A lot of them were in 19-inch racks or bench-type consoles.



A striking feature of these "prop" panels was the lack of labeling on any of
the devices unless, again, a particular device had a role in the story (e.g.
the radiation meter on an out-of-control reactor). But then, I guess a
scientist who's smart enough to invent a time machine or inter-dimensional
portal should be able to remember what switch does what.



Another electronics tidbit from the series: in one episode, a scientist had
developed a way to rapidly advance an individual primate's (including
human's) evolution, based on the premise that an organism's future form is
already encoded in its DNA and can brought out by the use of a machine built
for that task. To show a visitor how effective this technique was, the
scientist pointed to one of his successes - a chimpanzee seated at a bench
in a corner of the lab, quite convincingly using a VOM to troubleshoot some
piece of vacuum-tube electronics!



Albert


Re: Low cost Scope-Mobile alternatives?

Leon Robinson
 

You might look at some of these.https://www.harborfreight.com/catalogsearch/result/index/?dir=asc&order=EAScore%2Cf%2CEAFeatured+Weight%2Cf%2CSale+Rank%2Cf&q=utility+cart
 Leon Robinson    K5JLR

Political Correctness is a Political Disease.

From: Dewey Wyatt <kn4wddewey@...>
To: "TekScopes@groups.io" <TekScopes@groups.io>
Sent: Tuesday, July 10, 2018 4:34 PM
Subject: Re: [TekScopes] Low cost Scope-Mobile alternatives?

Made mine from a half sheet of ¾ plywood. Added wheels and a folding shelf, around 30.00 invested and around 2 hrs time.

Sent from Mail for Windows 10

From: Al Holt
Sent: Tuesday, July 10, 2018 5:30 PM
To: TekScopes@groups.io
Subject: [TekScopes] Low cost Scope-Mobile alternatives?

I'd like to get my 7603 'scope onto some sort of roll around cart, but I'd like to see if it can be done within some sort of reasonable price range. This is just for getting the thing from room to room around my house and not in any professional workplace.

Do you think one of those 3-tier wire shelving units might work, and work well? The cheapest thing I've come across is a $19 wire shelf at WalMart, but it would have to have threaded casters added to get it mobile. https://www.walmart.com/ip/Hyper-Tough-3-Tier-Rack-Black/143377471 is what they have. I'm not sure if the legs will take 'standard' threaded casters, though.

There are lots of alternatives, it would be nice to find one that is known to work well.

Ideas? Thanks for the help!!

--Al






---
This email has been checked for viruses by AVG.
https://www.avg.com


Re: Low cost Scope-Mobile alternatives?

Dewey Wyatt
 

Made mine from a half sheet of ¾ plywood. Added wheels and a folding shelf, around 30.00 invested and around 2 hrs time.

Sent from Mail for Windows 10

From: Al Holt
Sent: Tuesday, July 10, 2018 5:30 PM
To: TekScopes@groups.io
Subject: [TekScopes] Low cost Scope-Mobile alternatives?

I'd like to get my 7603 'scope onto some sort of roll around cart, but I'd like to see if it can be done within some sort of reasonable price range. This is just for getting the thing from room to room around my house and not in any professional workplace.

Do you think one of those 3-tier wire shelving units might work, and work well? The cheapest thing I've come across is a $19 wire shelf at WalMart, but it would have to have threaded casters added to get it mobile. https://www.walmart.com/ip/Hyper-Tough-3-Tier-Rack-Black/143377471 is what they have. I'm not sure if the legs will take 'standard' threaded casters, though.

There are lots of alternatives, it would be nice to find one that is known to work well.

Ideas? Thanks for the help!!

--Al






---
This email has been checked for viruses by AVG.
https://www.avg.com


Low cost Scope-Mobile alternatives?

Al Holt
 

I'd like to get my 7603 'scope onto some sort of roll around cart, but I'd like to see if it can be done within some sort of reasonable price range. This is just for getting the thing from room to room around my house and not in any professional workplace.

Do you think one of those 3-tier wire shelving units might work, and work well? The cheapest thing I've come across is a $19 wire shelf at WalMart, but it would have to have threaded casters added to get it mobile. https://www.walmart.com/ip/Hyper-Tough-3-Tier-Rack-Black/143377471 is what they have. I'm not sure if the legs will take 'standard' threaded casters, though.

There are lots of alternatives, it would be nice to find one that is known to work well.

Ideas? Thanks for the help!!

--Al


Re: SD-24 differential TDR on USB cables

Leo Bodnar
 

I would like to correct my mistake - common mode impedance of the full/high-speed USB 2.0 cable is 30 Ohms ±30%
Differential impedance is 90 Ω ±15%

This is from Table 7-12 in USB spec 2.0

Thanks
Leo


7A29 attenuator fault corrosion issue

Adrian
 

I don't know if this is a common issue (google didn't find it for me anyway) so just in case it helps others this is what I found.

Now that the 7912AD is behaving reasonably well I thought I would take a look at the 7A29 because some of the steps in the attenuator were off and on anything other that 'straight-thru' (10mV) range the rise-time was horrid.

My assumption was that some of the yoke adjusting screws needed tweaking to get the stage switches working right but once I got the thing out and started checking end-to-end resistance I realized that the resistances on anything that used the middle element were not sensible at all and visions of toasty black resistor elements began to swim in my head!

On stripping off the bottom - non actuator side - plate** I was reassured that the resistor substrates looked a normal color and careful probing showed the series resistances on the first and third elements were correct but the center one was giving weird (and slightly unstable) values. I then removed the screws from the other plate and lifted off the aluminum side blocks thus removing the ground connections to all the elements whereupon each individual resistor element on the substrate measured correctly.

It looks as if the ground connections from the resistive elements to the aluminum side blocks are made with some sort of (elastomer?) material and there was a nice white discoloration along the contact face - presumably aluminum oxide - once that was all cleaned up with cotton bud and IPA and reassembled all was good in the world and the attenuator seems spot on! I was careful to put all the actuator pins back in the holes they came from and no tweaking of yoke screws was needed, which is just as well as they seem to have been locked in place with a blob of nail-varnish in a tasteful shade of red but the adhesive properties of two-part epoxy resin!

**TIP - it is important to remove the two SMA connector end plates BEFORE lifting the bottom plate, the center pin of the SMA is slotted and the switched line keys into it, great care is needed to correctly engage this on re-assembly too!

Adrian


S3110 update

Pete Lancashire
 

With the help of a friend I came home yesterday with two R230 Parts units
they're clean but they've been in a mouse infested Barn for years. We also
brought home a 3T5 that looks complete.

The biggest surprise is I was able to find 2 of the interconnect cables the
go-between the r230 and the 568.

I was able to locate enough S3A's on eBay to get started. The only thing I
don't have is the usual accessories and the power supplies. If any of you
have them available please let me know.

I have been loaned a paddleboard the one used to connect the plugins to the
rear IO. If I have enough energy I will CAD it out and get some quotes. Get
something like 50 of them made and then the excess I will give away two
other owners of this kit.

If I don't have the energy to draw out I will hire somebody.

That's all for now

-pete


Re: [OT] Philips PP 1071 electronic switch unit

Sebastian Garcia
 

Thank you, Michael. Actually I have only pieces of it (most pieces, I think), so an schematic would be ideal for making sense of them.

Best regards,
Sebastian.



Michael A. Terrell 4:19am #149579

It appears to be two, 15MHz amplifiers to convert a single channel scope into a four channel display. In other words, it is a pair of the electronic switches that were common for early single channel scopes.

They were also kit versions and construction projects. They used a twin Triode to create an adjustable square wave to drive the chopper, and each input had an amplifier with adjustments for both gain and position. Heathkit made the S1, S2 and S3, ID22, models, and at least the S3 schematic is on line because I have a copy of its schematic.

There is a description of this item in a book about scopes:

<https://books.google.com/books?id=ytjqCAAAQBAJ&pg=PA300&lpg=PA300&dq=philips+PP1071+switch&source=bl&ots=s2KjeBGL9a&sig=DHny9MiSMGcX0EKubSBjGYsfn1s&hl=en&sa=X&ved=0ahUKEwjZob32r5TcAhUKOawKHZj0AwsQ6AEIPDAH#v=onepage&q=philips%20PP1071%20switch&f=false>

Here is the Heathkit S-3S schematic:

<http://www.heathkit-museum.com/test/images/s-3s.jpg>


You have an advantage in having two switches, in that you can compare them to locate problems. As always, make sure the DC rails in the power supply are clean. The filter caps are likely 50 years old, or more.


Michael A. Terrell

-----Original Message-----
From: Sebastian Garcia <sg-listas@...>
Sent: Jul 9, 2018 11:06 PM
To: TekScopes@groups.io
Subject: [TekScopes] [OT] Philips PP 1071 electronic switch unit

Hi, Could somebody provide the schematics/manual of this equipment (or similar Philips model) [1] ?
It is an (independent, including power supply) chopping unit, to turn any single trace scope into a into 2-trace one.
Mainly tube-based, some silicon diodes, a couple of selenium rectifier bridges, some power transistors. Seems to be from ~1960/65.

Any data would be greatly appreciated,
Sebastian.

[1] Philips PP 1071 electronic switch unit
https://www.radiomuseum.org/r/philips_pp1071_pp_107.html


Re: [OT] Philips PP 1071 electronic switch unit

Michael A. Terrell
 

It appears to be two, 15MHz amplifiers to convert a single channel scope into a four channel display. In other words, it is a pair of the electronic switches that were common for early single channel scopes.

They were also kit versions and construction projects. They used a twin Triode to create an adjustable square wave to drive the chopper, and each input had an amplifier with adjustments for both gain and position. Heathkit made the S1, S2 and S3, ID22, models, and at least the S3 schematic is on line because I have a copy of its schematic.

There is a description of this item in a book about scopes:

<https://books.google.com/books?id=ytjqCAAAQBAJ&pg=PA300&lpg=PA300&dq=philips+PP1071+switch&source=bl&ots=s2KjeBGL9a&sig=DHny9MiSMGcX0EKubSBjGYsfn1s&hl=en&sa=X&ved=0ahUKEwjZob32r5TcAhUKOawKHZj0AwsQ6AEIPDAH#v=onepage&q=philips%20PP1071%20switch&f=false>

Here is the Heathkit S-3S schematic:

<http://www.heathkit-museum.com/test/images/s-3s.jpg>


You have an advantage in having two switches, in that you can compare them to locate problems. As always, make sure the DC rails in the power supply are clean. The filter caps are likely 50 years old, or more.


Michael A. Terrell

-----Original Message-----
From: Sebastian Garcia <sg-listas@...>
Sent: Jul 9, 2018 11:06 PM
To: TekScopes@groups.io
Subject: [TekScopes] [OT] Philips PP 1071 electronic switch unit

Hi, Could somebody provide the schematics/manual of this equipment (or similar Philips model) [1] ?
It is an (independent, including power supply) chopping unit, to turn any single trace scope into a into 2-trace one.
Mainly tube-based, some silicon diodes, a couple of selenium rectifier bridges, some power transistors. Seems to be from ~1960/65.

Any data would be greatly appreciated,
Sebastian.

[1] Philips PP 1071 electronic switch unit
https://www.radiomuseum.org/r/philips_pp1071_pp_107.html



[OT] Philips PP 1071 electronic switch unit

Sebastian Garcia
 

Hi, Could somebody provide the schematics/manual of this equipment (or similar Philips model) [1] ?
It is an (independent, including power supply) chopping unit, to turn any single trace scope into a into 2-trace one.
Mainly tube-based, some silicon diodes, a couple of selenium rectifier bridges, some power transistors. Seems to be from ~1960/65.

Any data would be greatly appreciated,
Sebastian.

[1] Philips PP 1071 electronic switch unit
https://www.radiomuseum.org/r/philips_pp1071_pp_107.html


Re: Tek Temperature Coefficient on precision resistor

Ed Breya
 

Yes, that would be about right. T9 = 25ppm is one of the standard ones. Somewhere, there should be listings on line, of the various codes from T0 to around T15 or maybe higher.

Ed


Tek Temperature Coefficient on precision resistor

victor.silva
 

Can anyone confirm that Tektronix TC=T9 is equivalent to 25ppm temp coeff. on precision resistors.

On the 2465B Tektronix specifies TNPW1206-1006BT TC=T9, which I believe are 25ppm T/C resistors (the rest I know, 1206, 10k, 0.1%, thin film)
These are used in the reference for the A/D on the A5 module.

Thanks,
Victor


Re: 634 Monitor HV board issue

Dave Wise
 

Sounds like a well-known problem with Tek HV transformers of a certain era. They picked an impregnant which today becomes lossy when hot, and the transformer goes into thermal runaway. The best fix is to rewind. Chuck Harris has a machine, but I don't think he has a recipe for the 634.

It can also be done by hand, although it's tedious. For example, see topic and album "453 HV Transformer Rewind", where I developed a machine and procedure from ordinary household objects. Years later, my transformer is still working perfectly. You'll have to figure out wire sizes and turns, unless someone has the spec sheet.

HTH,
Dave Wise
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Adrian <Adrian@...>
Sent: Monday, July 09, 2018 8:41 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] 634 Monitor HV board issue

Having spent some more time on this I'm now wondering if the issue could be the transformer 20V primary? Do these things tend to develop shorted turns? I ask because I seem to have a normal image for the 10-15 seconds before the primary current has ramped to the point (a) my nerve fails (~2.5A) and (b) the drive transistor is cooking, so I switch off which makes me think the voltage multiplier is working?

Thanks,
Adrian