Date   

Re: New to the group with a few questions

Tom Jobe <tomjobe@...>
 

Hello Leetmaster,
If you were able to remove the 3-48 set screw somehow, a 3/32 (.0935"
across the flats nominally) Allen wrench would not even fit into the
empty threaded hole, so something must be wrong with the details of what
you think you have.
In my very limited experience, Tektronix only used two small set screw
sizes on the control knobs and they use either a .050" or a 1/16"
(.0635" nominal size) Allen wrench.
The only small Allen wrenches i have seen that really work well are the
ones ground from solid tool steel that the radio control modelers use.
You can buy them at your local RC model shop, or online... I have done both.
The lesser Allen wrenches up through even the Whia and equivalent
premium brands are just not up to the job on the smaller size hex
wrenches in my experience.
tom jobe...


On 10/21/2015 1:08 PM, leetmaster4004@yahoo.com [TekScopes] wrote:

I did know that it can only go in the vertical slot. It looks like
they just re-purposed that button to turn off the output from the
module. That seems to be the sole functional difference between the
5CT1N and the 7.

An additional problem I forgot to bring up in my first post.


I picked up a 7D01 recently and am stripping it down to make some
repairs. I have two set screws that I can't find the correct size hex
wrench to remove. The manual states they are "SETSCREW :3-48 X 0 .095
INCH,HEX SOC STL"

3-48 is the set-screw size and thread spacing but I haven't been able
to find a hex wrench of size .095 inch. Has anyone come across the
right tool for these and if so where do I get one?

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



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


Re: 067-0513-00 Pulse Generator

 

Hi Ancel,

Avalanche generators have a limited repetition rate of a few hundred KHz. So
unless you were going to drive it with something like a 100KHz Xtal this
wouldn't be a good combination.

Generally, you don't see Avalanche mode or Tunnel Diode pulse generators
combined with crystal oscillators. I'm not sure exactly why that is. Current
mode switching logic driven by crystal oscillators is a better combination.
Current mode logic (CML) has few aberrations, fast rise and fall (30pSec),
and it outputs pulses that have flat tops and bottoms. CML can easily be
driven by a crystal oscillator of almost any frequency to make a time mark
generator.

Time-Mark Generators for scope calibration don't need high accuracy. Their
accuracy only needs to be 10X the most accurate sweep speed of your scope.
Most scopes have 1% to 2% sweep accuracy at best so a time base with 0.1% or
better accuracy will suffice. Tek made a nice, versatile Time-Mark Generator
- the 2901 - you can usually find for less than $100. It has a huge range of
time pulse outputs designed specifically for calibrating scopes and it is
crystal controlled for better than 0.001% accuracy.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 6:22 PM
To: TekScopes@yahoogroups.com
Subject: Re: [TekScopes] Re: 067-0513-00 Pulse Generator

On Wed, 21 Oct 2015 19:00:04 -0400, you wrote:

Well with some spec sheet reading:
This looks useful:
http://www.farnell.com/datasheets/1903291.pdf
@$16 ea.

Feed it a logic signal and it will sharpen up the rise/fall to the sub
40 ps category with 50ohm termination built in. 400mV p-p 80ps min PW.

Questions I have:
1) Would this be a viable alt to the tunnel diode Tr bandwidth checking?
It will work find for bandwidth checking assuming that the pulse fidelity
shown in the datasheet can be maintained. That in itself may not be easy to
verify at high bandwidths without a sampling oscilloscope.

2) With an OXCO driven clk, would this be an alt to a time mark gen for
cal purposes?
A time mark generator for an analog oscilloscope does not need the accuracy
of an OXCO. A standard crystal is at least 20 times better than required.


------------------------------------
Posted by: David <davidwhess@gmail.com>
------------------------------------


------------------------------------

Yahoo Groups Links


Re: 067-0513-00 Pulse Generator

 

On Wed, 21 Oct 2015 19:00:04 -0400, you wrote:

Well with some spec sheet reading:
This looks useful:
http://www.farnell.com/datasheets/1903291.pdf
@$16 ea.

Feed it a logic signal and it will sharpen up the rise/fall to the sub
40 ps category with 50ohm termination built in. 400mV p-p
80ps min PW.

Questions I have:
1) Would this be a viable alt to the tunnel diode Tr bandwidth checking?
It will work find for bandwidth checking assuming that the pulse
fidelity shown in the datasheet can be maintained. That in itself may
not be easy to verify at high bandwidths without a sampling
oscilloscope.

2) With an OXCO driven clk, would this be an alt to a time mark gen for
cal purposes?
A time mark generator for an analog oscilloscope does not need the
accuracy of an OXCO. A standard crystal is at least 20 times better
than required.


Re: 2465B power supply - Sprague 290uF/200V big blue caps

vdonisa
 

Nope.

Look, there are millions of capacitors in use (for many decades now), in small signal coupling circuits, or in power AC applications, where they see little to no DC bias. Yet they fail to fail in a manner that could be attributed to the VDC/VDCmax ratio.

And, in the other corner, we have someone with an unproven allegation, shifting the burden of proof on everybody else to disprove his theory.

Well, there's also a teapot full of alien eggs orbiting Earth. Disprove that please. ;-)



---In TekScopes@yahoogroups.com, <david_wise@...> wrote :

I agree, but aren't you reversing your position?

Dave Wise

-----Original Message-----
From: TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 4:59 PM
To: TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com
Subject: RE: [TekScopes] Re: 2465B power supply - Sprague 290uF/200V big blue caps

Not exactly. I'm saying that when trying to find a substitute cap, ESR, ripple current and thermal/size characteristics have priority over exactly matching voltage. Messing those has proven, well documented, dramatic effects. While "undervolting" doesn't.

In fact I'm not even original. Quote from another CDE document:

"Higher rated voltage capacitors may be substituted for lower rated voltage capacitors as long as case size, DF, and ESR ratings are also compatible."

(full document here: http://www.cde.com/resources/catalogs/AEappGUIDE.pdf http://www.cde.com/resources/catalogs/AEappGUIDE.pdf http://www.cde.com/resources/catalogs/AEappGUIDE.pdf http://www.cde.com/resources/catalogs/AEappGUIDE.pdf )


---In TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com, <david_wise@...> wrote :

I didn't. I remembered it wrong.

You're saying that with a 100V part, 1V is as good as 100V, are you?

Dave Wise

-----Original Message-----
From: TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 3:44 PM
To: TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com
Subject: RE: [TekScopes] Re: 2465B power supply - Sprague 290uF/200V big blue caps

Where did you see the mention "near rated voltage"? It plainly says:

"In electrolytic capacitors, applying DC voltage actually drives a beneficial, on-going electrochemical reaction that heals defects in the anode dielectric."

Followed shortly by a description of the negative effects of simultaneously maxing out on both voltage and current/temperature.

---In TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com, <david_wise@...> wrote :

I read CDE_Multipliers.pdf, and they do claim that operating near rated voltage has the beneficial effect of repairing weak spots in the dielectric. Their graph of voltage life multipliers also stops at half of rated voltage.

I don't know how strongly this correlates with the useful life of a cap operated below rating. I suppose a graph would show a sweet spot with maximum life, with less at each end. I can't begin to guess at the shape of the tails.

The Shelf Life rating is based on storage at rated temperature. We don't know the degree to which thinning is accelerated by heat, although Arrhenius would be a reasonable first guess. A cap stored at comfortable room temperature will last much longer than the rating.

The Shelf Life test also applies rated voltage after storage. If the circuit applies only low voltage, this test will reject caps that operate just fine.

I just can't get righteous over this, but certainly there is *some* effect. We just don't know how much, and the people who research this for a living don't care about this operating point. I'm determined not to lose sleep over it.

Dave Wise

-----Original Message-----
From: TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 12:29 PM
To: vdonisa@... mailto:vdonisa@... [TekScopes]
Subject: Re: [TekScopes] Re: 2465B power supply - Sprague 290uF/200V big blue caps

On Tue, 20 Oct 2015, vdonisa@... mailto:vdonisa@... [TekScopes] wrote:

*PLONK*

>
> Thanks.
>
> I suggest in the future you also take it with Cornell Dubillier:
>
> https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1
>
> EPCOS/TDK:
>
> http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf
>
> and Illinois Capacitor:
>
> http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx
>
> to name just a few.
>
>







------------------------------------
Posted by: vdonisa@... mailto:vdonisa@...
------------------------------------


------------------------------------

Yahoo Groups Links







------------------------------------
Posted by: vdonisa@... mailto:vdonisa@...
------------------------------------


------------------------------------

Yahoo Groups Links


Re: 2465B power supply - Sprague 290uF/200V big blue caps

Dave Wise
 

I agree, but aren't you reversing your position?

Dave Wise

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 4:59 PM
To: TekScopes@yahoogroups.com
Subject: RE: [TekScopes] Re: 2465B power supply - Sprague 290uF/200V big blue caps

Not exactly. I'm saying that when trying to find a substitute cap, ESR, ripple current and thermal/size characteristics have priority over exactly matching voltage. Messing those has proven, well documented, dramatic effects. While "undervolting" doesn't.

In fact I'm not even original. Quote from another CDE document:

"Higher rated voltage capacitors may be substituted for lower rated voltage capacitors as long as case size, DF, and ESR ratings are also compatible."

(full document here: http://www.cde.com/resources/catalogs/AEappGUIDE.pdf http://www.cde.com/resources/catalogs/AEappGUIDE.pdf )


---In TekScopes@yahoogroups.com, <david_wise@...> wrote :

I didn't. I remembered it wrong.

You're saying that with a 100V part, 1V is as good as 100V, are you?

Dave Wise

-----Original Message-----
From: TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 3:44 PM
To: TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com
Subject: RE: [TekScopes] Re: 2465B power supply - Sprague 290uF/200V big blue caps

Where did you see the mention "near rated voltage"? It plainly says:

"In electrolytic capacitors, applying DC voltage actually drives a beneficial, on-going electrochemical reaction that heals defects in the anode dielectric."

Followed shortly by a description of the negative effects of simultaneously maxing out on both voltage and current/temperature.

---In TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com, <david_wise@...> wrote :

I read CDE_Multipliers.pdf, and they do claim that operating near rated voltage has the beneficial effect of repairing weak spots in the dielectric. Their graph of voltage life multipliers also stops at half of rated voltage.

I don't know how strongly this correlates with the useful life of a cap operated below rating. I suppose a graph would show a sweet spot with maximum life, with less at each end. I can't begin to guess at the shape of the tails.

The Shelf Life rating is based on storage at rated temperature. We don't know the degree to which thinning is accelerated by heat, although Arrhenius would be a reasonable first guess. A cap stored at comfortable room temperature will last much longer than the rating.

The Shelf Life test also applies rated voltage after storage. If the circuit applies only low voltage, this test will reject caps that operate just fine.

I just can't get righteous over this, but certainly there is *some* effect. We just don't know how much, and the people who research this for a living don't care about this operating point. I'm determined not to lose sleep over it.

Dave Wise

-----Original Message-----
From: TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 12:29 PM
To: vdonisa@... mailto:vdonisa@... [TekScopes]
Subject: Re: [TekScopes] Re: 2465B power supply - Sprague 290uF/200V big blue caps

On Tue, 20 Oct 2015, vdonisa@... mailto:vdonisa@... [TekScopes] wrote:

*PLONK*

>
> Thanks.
>
> I suggest in the future you also take it with Cornell Dubillier:
>
> https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1
>
> EPCOS/TDK:
>
> http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf
>
> and Illinois Capacitor:
>
> http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx
>
> to name just a few.
>
>







------------------------------------
Posted by: vdonisa@... mailto:vdonisa@...
------------------------------------


------------------------------------

Yahoo Groups Links



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



------------------------------------
Posted by: vdonisa@yahoo.com
------------------------------------


------------------------------------

Yahoo Groups Links


Re: 2465B power supply - Sprague 290uF/200V big blue caps

vdonisa
 

Not exactly. I'm saying that when trying to find a substitute cap, ESR, ripple current and thermal/size characteristics have priority over exactly matching voltage. Messing those has proven, well documented, dramatic effects. While "undervolting" doesn't.

In fact I'm not even original. Quote from another CDE document:

"Higher rated voltage capacitors may be substituted for lower rated voltage capacitors as long as case size, DF, and ESR ratings are also compatible."

(full document here: http://www.cde.com/resources/catalogs/AEappGUIDE.pdf http://www.cde.com/resources/catalogs/AEappGUIDE.pdf )


---In TekScopes@yahoogroups.com, <david_wise@...> wrote :

I didn't. I remembered it wrong.

You're saying that with a 100V part, 1V is as good as 100V, are you?

Dave Wise

-----Original Message-----
From: TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 3:44 PM
To: TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com
Subject: RE: [TekScopes] Re: 2465B power supply - Sprague 290uF/200V big blue caps

Where did you see the mention "near rated voltage"? It plainly says:

"In electrolytic capacitors, applying DC voltage actually drives a beneficial, on-going electrochemical reaction that heals defects in the anode dielectric."

Followed shortly by a description of the negative effects of simultaneously maxing out on both voltage and current/temperature.

---In TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com, <david_wise@...> wrote :

I read CDE_Multipliers.pdf, and they do claim that operating near rated voltage has the beneficial effect of repairing weak spots in the dielectric. Their graph of voltage life multipliers also stops at half of rated voltage.

I don't know how strongly this correlates with the useful life of a cap operated below rating. I suppose a graph would show a sweet spot with maximum life, with less at each end. I can't begin to guess at the shape of the tails.

The Shelf Life rating is based on storage at rated temperature. We don't know the degree to which thinning is accelerated by heat, although Arrhenius would be a reasonable first guess. A cap stored at comfortable room temperature will last much longer than the rating.

The Shelf Life test also applies rated voltage after storage. If the circuit applies only low voltage, this test will reject caps that operate just fine.

I just can't get righteous over this, but certainly there is *some* effect. We just don't know how much, and the people who research this for a living don't care about this operating point. I'm determined not to lose sleep over it.

Dave Wise

-----Original Message-----
From: TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 12:29 PM
To: vdonisa@... mailto:vdonisa@... [TekScopes]
Subject: Re: [TekScopes] Re: 2465B power supply - Sprague 290uF/200V big blue caps

On Tue, 20 Oct 2015, vdonisa@... mailto:vdonisa@... [TekScopes] wrote:

*PLONK*

>
> Thanks.
>
> I suggest in the future you also take it with Cornell Dubillier:
>
> https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1
>
> EPCOS/TDK:
>
> http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf
>
> and Illinois Capacitor:
>
> http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx
>
> to name just a few.
>
>







------------------------------------
Posted by: vdonisa@... mailto:vdonisa@...
------------------------------------


------------------------------------

Yahoo Groups Links


Re: 067-0513-00 Pulse Generator

 

What is needed to get rise times faster than 100 picoseconds with an
avalanche pulse generator?

Is all surface mount construction sufficient? I suspect the lead
inductance is the major limitation. A transistor with dual leads on
the collector and emitter would be handy for this.

I am not impressed with the aberrations of the avalanche pulse
generator design at the silionvalleygarage link. If I went this
route, I would try adding a diode disconnect circuit which is common
in flat level pulse generators.

On Wed, 21 Oct 2015 13:31:18 -0700, you wrote:

Hi Roger,
As you point out avalanche transistor pulsers are incredibly simple to
build. Almost any transistor will work, and a short piece of coax is all you
need to stretch the pulse. Plus they generate a lot of voltage (unlike TDs)
which in some cases is a plus. Early in my career I built one and was really
impressed at the results.

If you are very careful you can get rise times under 30pSec. But generally
speaking it takes a good sampler to be able to measure those kinds of edge
speeds. Somewhere about a year ago on the internet I came across somebody
that published the test results of the avalanche speeds he measured of about
15 0r 20 transistors. They were all pretty fast but some were incredible. I
wish I could remember where I saw that list.

Dennis Tillman W7PF


Re: 2465B power supply - Sprague 290uF/200V big blue caps

Dave Wise
 

I didn't. I remembered it wrong.

You're saying that with a 100V part, 1V is as good as 100V, are you?

Dave Wise

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 3:44 PM
To: TekScopes@yahoogroups.com
Subject: RE: [TekScopes] Re: 2465B power supply - Sprague 290uF/200V big blue caps

Where did you see the mention "near rated voltage"? It plainly says:

"In electrolytic capacitors, applying DC voltage actually drives a beneficial, on-going electrochemical reaction that heals defects in the anode dielectric."

Followed shortly by a description of the negative effects of simultaneously maxing out on both voltage and current/temperature.

---In TekScopes@yahoogroups.com, <david_wise@...> wrote :

I read CDE_Multipliers.pdf, and they do claim that operating near rated voltage has the beneficial effect of repairing weak spots in the dielectric. Their graph of voltage life multipliers also stops at half of rated voltage.

I don't know how strongly this correlates with the useful life of a cap operated below rating. I suppose a graph would show a sweet spot with maximum life, with less at each end. I can't begin to guess at the shape of the tails.

The Shelf Life rating is based on storage at rated temperature. We don't know the degree to which thinning is accelerated by heat, although Arrhenius would be a reasonable first guess. A cap stored at comfortable room temperature will last much longer than the rating.

The Shelf Life test also applies rated voltage after storage. If the circuit applies only low voltage, this test will reject caps that operate just fine.

I just can't get righteous over this, but certainly there is *some* effect. We just don't know how much, and the people who research this for a living don't care about this operating point. I'm determined not to lose sleep over it.

Dave Wise

-----Original Message-----
From: TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 12:29 PM
To: vdonisa@... mailto:vdonisa@... [TekScopes]
Subject: Re: [TekScopes] Re: 2465B power supply - Sprague 290uF/200V big blue caps

On Tue, 20 Oct 2015, vdonisa@... mailto:vdonisa@... [TekScopes] wrote:

*PLONK*

>
> Thanks.
>
> I suggest in the future you also take it with Cornell Dubillier:
>
> https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1 https://www.digikey.com/Web%20Export/Supplier%20Content/CDE_338/PDF/CDE_Multipliers.pdf?redirected=1
>
> EPCOS/TDK:
>
> http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf http://en.tdk.eu/designtools/alu_useful_life/Useful_life.swf
>
> and Illinois Capacitor:
>
> http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx
>
> to name just a few.
>
>







------------------------------------
Posted by: vdonisa@yahoo.com
------------------------------------


------------------------------------

Yahoo Groups Links


Re: 067-0513-00 Pulse Generator

mosaicmerc
 

Well with some spec sheet reading:
This looks useful:
http://www.farnell.com/datasheets/1903291.pdf
@$16 ea.

Feed it a logic signal and it will sharpen up the rise/fall to the sub 40 ps category with 50ohm termination built in. 400mV p-p
80ps min PW.

Questions I have:
1) Would this be a viable alt to the tunnel diode Tr bandwidth checking?
2) With an OXCO driven clk, would this be an alt to a time mark gen for cal purposes?


Re: 2465B power supply - Sprague 290uF/200V big blue caps

vdonisa
 

Where did you see the mention "near rated voltage"? It plainly says:

"In electrolytic capacitors, applying DC voltage actually drives a beneficial, on-going electrochemical reaction that heals defects in the anode dielectric."

Followed shortly by a description of the negative effects of simultaneously maxing out on both voltage and current/temperature.

---In TekScopes@yahoogroups.com, <david_wise@...> wrote :

I read CDE_Multipliers.pdf, and they do claim that operating near rated voltage has the beneficial effect of repairing weak spots in the dielectric. Their graph of voltage life multipliers also stops at half of rated voltage.

I don't know how strongly this correlates with the useful life of a cap operated below rating. I suppose a graph would show a sweet spot with maximum life, with less at each end. I can't begin to guess at the shape of the tails.

The Shelf Life rating is based on storage at rated temperature. We don't know the degree to which thinning is accelerated by heat, although Arrhenius would be a reasonable first guess. A cap stored at comfortable room temperature will last much longer than the rating.

The Shelf Life test also applies rated voltage after storage. If the circuit applies only low voltage, this test will reject caps that operate just fine.

I just can't get righteous over this, but certainly there is *some* effect. We just don't know how much, and the people who research this for a living don't care about this operating point. I'm determined not to lose sleep over it.

Dave Wise


Sold ( FS: assorted Tektronix PC boards)

Brad Thompson <brad.thompson@...>
 

Hello--

My thanks go to everyone who inquired.

73--

Brad AA1IP


Re: 067-0513-00 Pulse Generator

Brad Thompson <brad.thompson@...>
 

On 10/21/2015 4:31 PM, 'Dennis Tillman' dennis@ridesoft.com [TekScopes] wrote:

<snip> Somewhere about a year ago on the internet I came across somebody
that published the test results of the avalanche speeds he measured of about
15 0r 20 transistors. They were all pretty fast but some were incredible. I
wish I could remember where I saw that list.
Hello--

I couldn't locate that list either, but I stumbled across this paper...

"Nanosecond switching of power MOSFET" in which the authors use a 2N3904 in avalanche mode
to charge a MOSFET's gate capacitance really quickly:

cmosedu.com/jbaker/papers/1990/RSI81990.pdf

...Which was intriguing enough to call to the group's attention.
73--

Brad AA1IP


Re: New to the group with a few questions

James
 

The display button is just fine for me as while I've been learning the equipment its been helpful to have a no questions asked simple OFF button on a module. My 7613 doesn't have em but everything I find says the 7000's are the bigger badder brother of the 5000's so they probably need the space for more important things.

I'm in the US though my default measurement system is metric from my IT background. My first problem was assuming metric till I was reminded that this equipment was made during in the US during the cold war so "standard" was the way to go.


I'll dig up a 3/32 hex wrench and see how that goes though I've had a bad feeling that the two setscrews are stripped as all the rest of the modules I am rebuilding have had the right feel when I was removing the setscrews. I work with Apple products from time to time so I am well versed in unreasonably tight tolerances and these two setscrews haven't been right since day one.


If they are indeed stripped any advice on further removal methods? I've never found a proper bit small enough for removing stripped laptop screws which are usually bigger than one of these.


Re: 067-0513-00 Pulse Generator

 

Hi David,
I looked at that same picture and decided it was a strange way the scope calculated the risetime. First, I think the scope picked the lowest point of the pulse (just prior to the rise the pulse baseline was nice and flat so that was easy) and it picked the highest point of the pules which was right before the pulse ended.

Then it looks like it chose the 20% and 80% points to determine the risetime. Tek normally uses the 10% and 90% points and they only look at the height of the rising edge.

Finally, this scope is supposed to be ultra-ultra-fast (according to him) so why didn't he take a screen shot of the rising edge alone at a faster sweep speed so we could see what the edge rise time was and what the rising edge actually looked like.

I'm still left with the impression he is trying to play down the negative aspects of his little pulser.

Over the years several other people have attempted to make and sell pocket size pulsers based on avalanche mode transistors but none has met with any commercial success. They are a tough sell. Maybe he will be the first.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 1:41 PM
Cc: TekScopes <TekScopes@yahoogroups.com>
Subject: Re: [TekScopes] Re: 067-0513-00 Pulse Generator

On Wed, Oct 21, 2015 at 2:24 PM, Dennis Tillman <dennis@ridesoft.com> wrote:

It is a cute little packaging job. But the most important information of all, the risetime, seems to be suspiciously missing from his writeup. He talks up this incredibly fast scope but the scope photo he includes makes it hard to tell the risetime of the pulse. It is as if he seems to have intentionally obfuscated the actual results. I agree with David that the rising edge doesn't look all that fast.
The screen shot at the end says 200ps:
http://www.siliconvalleygarage.com/_Media/screen-shot-2013-11-24-at_med.png

------------------------------------
Posted by: David DiGiacomo <telists@davmar.org>
------------------------------------


Re: New to the group with a few questions

 

Hi Lee,
Yes, that is the way the entire 5000 series works. Personally I have always
thought that the DISPLAY button at the top of 5000 series plugins is weird.
But since I did not have to deal with the design problems the engineers were
confronted with when they created these products it is a cheap shot on my
part when I call their choices weird.

Since on the internet it is impossible to know where you are I am going to
guess you are in one of those intelligent countries that has adopted the
metric system. The set screws Tek used are designed for the "other" system
(the English system) that uses inches. The nice thing about changing set
screws in Tek knobs is that there are only two sizes of hex wrench you need.
Buy a set of non-metric hex wrenches and you will be able to remove the set
screws. Don't try removing them with a metric hex wrench or you will strip
the head and then you are in real trouble.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 1:08 PM
To: TekScopes@yahoogroups.com
Subject: [TekScopes] Re: New to the group with a few questions

I did know that it can only go in the vertical slot. It looks like they just
re-purposed that button to turn off the output from the module. That seems
to be the sole functional difference between the 5CT1N and the 7.

An additional problem I forgot to bring up in my first post.

I picked up a 7D01 recently and am stripping it down to make some repairs.
I have two set screws that I can't find the correct size hex wrench to
remove. The manual states they are "SETSCREW :3-48 X 0 .095 INCH,HEX SOC
STL"

3-48 is the set-screw size and thread spacing but I haven't been able to
find a hex wrench of size .095 inch. Has anyone come across the right tool
for these and if so where do I get one?

------------------------------------
Posted by: leetmaster4004@yahoo.com
------------------------------------


Re: 067-0513-00 Pulse Generator

David DiGiacomo
 

On Wed, Oct 21, 2015 at 2:24 PM, Dennis Tillman <dennis@ridesoft.com> wrote:

It is a cute little packaging job. But the most important information of all, the risetime, seems to be suspiciously missing from his writeup. He talks up this incredibly fast scope but the scope photo he includes makes it hard to tell the risetime of the pulse. It is as if he seems to have intentionally obfuscated the actual results. I agree with David that the rising edge doesn't look all that fast.


The screen shot at the end says 200ps:

http://www.siliconvalleygarage.com/_Media/screen-shot-2013-11-24-at_med.png


Re: 2465B power supply - Sprague 290uF/200V big blue caps

Tothwolf
 

On Wed, 21 Oct 2015, Stefan Trethan stefan_trethan@gmx.at [TekScopes] wrote:

This one point below I find interesting amid all the mud slinging.

For any given section of foil the the voltage differential, and consequently the required dielectric thickness, should it not be the same?
Surely one spot on the foil does not know how large an area it is connected to, and would form (or rather thin down to) the thickness of dielectric prescribed by the voltage applied regardless of overall foil size?

Please discuss.
I'm done with this one I think. Until capacitor manufacturers begin mentioning minimum working voltages in their datasheets, some (not you, but you know who) will likely never be satisfied and will seek any means to justify their purchases ("audio grade" capacitors, anyone?). I've already spent far too many hours on this subject as it is and I still have a sizable stack of boards awaiting replacement of their single wipe DIP sockets that I really should have been working on instead. (Anyone want to argue that single wipe DIP sockets are reliable? :)

For those who find this this thread later on, I would personally recommend sticking with low-ESR parts, as the original PSU designers did, and not general purpose parts such as the Nichicon CS, which as I pointed out elsewhere in the thread, have a rather novel way of presenting their estimated service life in their datasheet (super long life...until you apply all the correction factors).

The real challenge I see with this PSU though, is choosing low-ESR components which have a similar ripple current rating to the original parts (for example, a modern 100uF 25V 6.3mm low-ESR part may well have a lower ripple current rating than the original 10mm diameter part). This is made even more difficult by the fact that some of these capacitors are of a critical value (at least one of the 100uF 25V parts /must/ be 100uF for the PSU to function correctly).

As an aside, this model of thinning dielectric leads me to question if capacitance rises in storage - which I am not aware of. It should, in view of the reduced dielectric thickness. Easily tried I guess.
That's an interesting question too. I'm not sure if any increase during storage would be easily measure given the already wide tolerance of these sort of components (just warming one with a hair dryer will tend to show a measurable change in capacitance). A larger value capacitor (larger foil surface area) might work better for such experiments than smaller values.

One that does tend to be easy to measure is the increase in capacitance as the capacitor ages in service. Some of this would be due to the dielectric thinning but a lot of it is also be due to erosion/pitting of the surface of the foils (however I imagine someone will argue against this, too).

...and since we are already on a contentious subject...the above is also why "reforming" of heavily used capacitors tends to be futile at best. Sometimes you can get enough dielectric growth during the reforming process to decrease the leakage current, but if the foil is already eroded from a long service life, it will be temporary as the dielectric thins when the capacitor is used at working voltage and/or stored (unused equipment sitting on the shelf). Better results might be obtained from NOS or barely used capacitors (assuming that the capacitor doesn't have other age-related problems, such as loss of electrolyte or corrosion of the foil to lead connections).


Re: 7854 Display problem

 

Hi Charlie,
Get a can of FreezIt or a can of compressed air upside down will give you
the same thing.
Warm up the scope so the readout is in the right place on the CRT, then very
carefully place a drop of FreezIt on each of the readout ICs inside the
scope one at a time and wait a minute for the FreezIt to do its thing before
moving to the next IC. That should locate the bad one that is causing the
problem. It could also be a resistor in the circuit that has a crack in it.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 12:48 PM
To: TekScopes@yahoogroups.com
Subject: [TekScopes] 7854 Display problem

I have a 7854 that works fine and is accurate. Some mornings when I power it
up the read outs are compressed towards the left about half way. The
readouts appear near normal size but are just shifted to the left. After
about 1-5 minutes the read outs move to their normal position and stay there
until the frame cools down. The cycle repeats at each power up once cooled.
The trace is never affected, only the readouts. The power supply has never
been serviced on this unit to the best of my knowledge.
Everything else works normally.
Any ideas about what might be causing this?

------------------------------------
Posted by: ctconger@gmail.com
------------------------------------


Re: 067-0513-00 Pulse Generator

 

Hi Roger,
As you point out avalanche transistor pulsers are incredibly simple to
build. Almost any transistor will work, and a short piece of coax is all you
need to stretch the pulse. Plus they generate a lot of voltage (unlike TDs)
which in some cases is a plus. Early in my career I built one and was really
impressed at the results.

If you are very careful you can get rise times under 30pSec. But generally
speaking it takes a good sampler to be able to measure those kinds of edge
speeds. Somewhere about a year ago on the internet I came across somebody
that published the test results of the avalanche speeds he measured of about
15 0r 20 transistors. They were all pretty fast but some were incredible. I
wish I could remember where I saw that list.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 11:56 AM
To: TekScopes@yahoogroups.com
Subject: [TekScopes] Re: 067-0513-00 Pulse Generator

I built a couple of avalanche circuits several months ago just hand wiring
as small as I could and only got risetimes around 400psec. I think that to
get really fast edges you need either a decent PCB layout or better eyesight
and soldering skills than I possess! They also need quite a bit of
attenuation before a sampling diode input. It might be worth mounting two
SMA sockets back-to-back with a SMD transistor bridging the centre pins and
using an external SMA attenuator?

I have used the NC7SZ14 CMOS Schmitt trigger to get 200psec fall times (the
rise is slower) using all SMD components directly on an SMA socket. I don't
know the SY100EP32 but will investigate.

I think the best thing for me to do with the 067-0513-00 is to make up
either a planar transmission line or an etched PCB line, test it with the
Russian TDs that I have and maybe find a faster TD later on. This way I
preserve something of the intention of the original design even if not its
performance and elegance.

Thanks again,

Roger





------------------------------------
Posted by: very_fuzzy_logic@yahoo.com
------------------------------------


------------------------------------

Yahoo Groups Links


Re: 067-0513-00 Pulse Generator

 

It is a cute little packaging job. But the most important information of all, the risetime, seems to be suspiciously missing from his writeup. He talks up this incredibly fast scope but the scope photo he includes makes it hard to tell the risetime of the pulse. It is as if he seems to have intentionally obfuscated the actual results. I agree with David that the rising edge doesn't look all that fast.

Dennis Tillman W7PF.

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com]
Sent: Wednesday, October 21, 2015 11:01 AM
Cc: TekScopes <TekScopes@yahoogroups.com>
Subject: Re: [TekScopes] Re: 067-0513-00 Pulse Generator

On Wed, Oct 21, 2015 at 11:05 AM, Ancel <mosaicmerc@yahoo.com> wrote:

This is quite interesting:
http://www.siliconvalleygarage.com/projects/picosecond-pulser.html
I don't know, it's a fair amount of trouble to go to for a paltry 200ps rise time. You can do better with a simple IC like an SY100EP32, or of course with a tunnel diode as we've been discussing.

------------------------------------
Posted by: David DiGiacomo <telists@davmar.org>
------------------------------------

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