Date   
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






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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

Re: 634 Monitor HV board issue

Adrian
 

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

Re: 7A13 Comparison Voltage coarse knob

Colin Herbert
 

Thanks for this info, Håkan. I was aware of the use on 7A22 (I own one) but not the others.
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of zenith5106
Sent: 06 July 2018 22:35
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7A13 Comparison Voltage coarse knob

The Tek part number for the knob is 366-1084-00 and it just may be used on
some other item of equipment.
This knob was also used on AM502, 26A2, 5A19N, 5A22N, 7A22, 7S11 & 7S12.

/Håkan

Re: Kludging together a TDR or similar?

 

On Thu, Jun 28, 2018 at 01:49 pm, Siggi wrote:


Alan Wolke did a video on TDR using a scrap box ~1ns pulser: <
https://www.youtube.com/watch?v=9cP6w2odGUc >. For ~$2 and a few minutes
soldering, you might be able to get useful results :).
I think you beat me to it :

https://www.youtube.com/watch?v=9cP6w2odGUc

Yup you did, I see the URL is identical. Nice that it is still there.

I was prompted fo get it because someone on Usenet is picking on one of the better members there and he said, probably sarcastically "How are you going to determine the twist in a CAT 5e cable ? He didn't ask me but I decided to answer anyway and I remembered the video that was sent to me by a cohort.

I think the guy knows what he's doing.

Re: Kludging together a TDR or similar?

Tom Gardner
 

On 08/07/18 16:11, cheater cheater wrote:
Sorry, having trouble picturing the circuit, mind explaining it in a bit
more detail? Add a netlist maybe?

On Sun, 8 Jul 2018, 10:12 Tom Gardner, <tggzzz@...> wrote:

On 08/07/18 04:53, Ed Breya via Groups.Io wrote:
If you are concerned about setting or controlling the frequency, you can
drive the output stage instead from another with XO or a generator. My
preferred 74AC driver for fast, strong pulsing is the 74AC541, with eight
amplifiers that can be paralleled. Also, the pinout is excellent for this
sort of thing, layout-wise - all ins on one side, and all outs on the other.
My preference is 74LVC1G*, which have ~7ohms output impedance, 32mA
drive, and
work from ~1V to 5V albeit with different risetimes.

If you add a 143ohm series resistance and put three of those in series
(and
decouple them very well), then you get a clean 50ohm output. I can't
measure the
risetime; it is certainly sub nanosecond, another measure gives ~600ps,
and I've
seen a (poorly controlled) measurement of 300ps on a 1GHz scope.
I note that I wrote "put three of those in series". I meant parallel.

  - 74lvc1g* - 143R -
 |                   |
-+- 74lvc1g* - 143R -+-
 |                   |
  - 74lvc1g* - 143R -

We are into the third week of a heatwave here; it must be cooking
my brain. Well, that's the least worrying alternative.

Re: Kludging together a TDR or similar?

Tom Gardner
 

On 08/07/18 16:11, cheater cheater wrote:
Sorry, having trouble picturing the circuit, mind explaining it in a bit
more detail? Add a netlist maybe?

On Sun, 8 Jul 2018, 10:12 Tom Gardner, <tggzzz@...> wrote:

On 08/07/18 04:53, Ed Breya via Groups.Io wrote:
If you are concerned about setting or controlling the frequency, you can
drive the output stage instead from another with XO or a generator. My
preferred 74AC driver for fast, strong pulsing is the 74AC541, with eight
amplifiers that can be paralleled. Also, the pinout is excellent for this
sort of thing, layout-wise - all ins on one side, and all outs on the other.
My preference is 74LVC1G*, which have ~7ohms output impedance, 32mA
drive, and
work from ~1V to 5V albeit with different risetimes.

If you add a 143ohm series resistance and put three of those in series
(and
decouple them very well), then you get a clean 50ohm output. I can't
measure the
risetime; it is certainly sub nanosecond, another measure gives ~600ps,
and I've
seen a (poorly controlled) measurement of 300ps on a 1GHz scope.



Re: Kludging together a TDR or similar?

 

Sorry, having trouble picturing the circuit, mind explaining it in a bit
more detail? Add a netlist maybe?

On Sun, 8 Jul 2018, 10:12 Tom Gardner, <tggzzz@...> wrote:

On 08/07/18 04:53, Ed Breya via Groups.Io wrote:
If you are concerned about setting or controlling the frequency, you can
drive the output stage instead from another with XO or a generator. My
preferred 74AC driver for fast, strong pulsing is the 74AC541, with eight
amplifiers that can be paralleled. Also, the pinout is excellent for this
sort of thing, layout-wise - all ins on one side, and all outs on the other.
My preference is 74LVC1G*, which have ~7ohms output impedance, 32mA
drive, and
work from ~1V to 5V albeit with different risetimes.

If you add a 143ohm series resistance and put three of those in series
(and
decouple them very well), then you get a clean 50ohm output. I can't
measure the
risetime; it is certainly sub nanosecond, another measure gives ~600ps,
and I've
seen a (poorly controlled) measurement of 300ps on a 1GHz scope.



Re: Kludging together a TDR or similar?

Tom Gardner
 

On 08/07/18 04:53, Ed Breya via Groups.Io wrote:
If you are concerned about setting or controlling the frequency, you can drive the output stage instead from another with XO or a generator. My preferred 74AC driver for fast, strong pulsing is the 74AC541, with eight amplifiers that can be paralleled. Also, the pinout is excellent for this sort of thing, layout-wise - all ins on one side, and all outs on the other.
My preference is 74LVC1G*, which have ~7ohms output impedance, 32mA drive,  and work from ~1V to 5V albeit with different risetimes.

If you add a 143ohm series resistance and put three of those in series (and decouple them very well), then you get a clean 50ohm output. I can't measure the risetime; it is certainly sub nanosecond, another measure gives ~600ps, and I've seen a (poorly controlled) measurement of 300ps on a 1GHz scope.

Re: Source for 1/8" fibreglass or other hard plastic rod in UK

John Parkins G8KVP
 

Hello David,

If you have a local B&Q have a look in there. They do a small range of
both metal and plastic rods as well as small angle, flat and tubes.



Saturday, July 7, 2018, 6:26:57 PM, you wrote:

DCP> I'm looking for a UK source of 1/8" (0.125" or 3.2mm) diameter fibreglass
DCP> rods (or other hard plastic) such as is used in many 7000 series plugins.

DCP> For the specific application (the rod down the middle of plastic expansion
DCP> rivet) a 3mm rod won't do.

DCP> I only want a small quantity, so any suppliers with large minimum orders
DCP> would be a problem.

DCP> Thanks
DCP> David


DCP>




--
Best regards,
John mailto:john@...