Maybe I need another 'scope?

On Tue, 20 Nov 2018 10:02:40 -0500, Ralph Mowery
<rmowery28146@earthlink.net> wrote:

In article <45a5d682-139d-4aaa-9ca2-b4d9243ea05e@googlegroups.com>,
tabbypurr@gmail.com says...

Maybe it's time to make some new tube testers.

While we're here, an iso won't help if you connect an earthed scope to the thing. It will bite you if you touch, and that's how HT is.




It is usually easier to just pop in a good tube instead of testing
unless looking for a matched set.

I have bought a $ 300 Hantek scope. It is suppose to be good to 200 MHz
and rated for 600 volts peak. Good thing about it, you can set the
screen up for waveform and digital volt meter. YOu see the waveform and
good resolution of voltage at the same time.

Sometimes it may be better or easier to just isolate the test equipment
from the ground and not the unit under test. I don't know how much the
solid scope draws without going to check, but it could probalby be
powered by 2 transformers of 24 volts at 2 amps or so placed back to
back.

I think I need to take a look at one of those.
Thanks,
Eric

 

On Tue, 20 Nov 2018 02:03:08 -0800 (PST), tabbypurr@gmail.com wrote:

On Tuesday, 20 November 2018 06:18:38 UTC, Phil Hobbs wrote:
On 11/19/18 7:01 PM, etpm@whidbey.com wrote:
Hey all youse 'scope gurus,

Anyway, do I need a different 'scope to to measure accurately what
is going on inside vacuum tube equipment?

no

If you all think another 'scope should be in my future I would love
some advice. Since this is a hobby I don't wanna spend a lot of money
on yet another toy, er tool. So a used 'scope is fine with me. I love
my used TEK 465B.

Everybody should have another scope now and again. I have 11 at the
moment, which is none too many.

(On average I pay about 3 cents on the dollar, which makes new scopes an
easier sell.)

Cheers

Phil Hobbs

If you're going to get one you don't need, consider making it a pocket scope. Quite handy, even with modest specs.


NT

I have been looking at some on eBay. Do you have any suggestions?
Thanks,
Eric

 

On Tue, 20 Nov 2018 08:08:50 -0500, Tim Schwartz <tim@bristolnj.com>
wrote:

Eric,

I'd suggest using a voltmeter (analog or digital, whatever you
prefer)for the DC voltage measurements. I like my old Heathkit VTVM for
troubleshooting, as you are unlikely to cause any serious damage to the
meter, as could happen with a digital.

The scope you have is all you need, as what you need it for is the AC
part of the waveform. Set the scope to AC coupling at the input and
you'll be looking at the ripple on the supply. If the ripple exceeds
400 volts (8 divisions at 5 volts each is 40Vp-p and with a 10x probe
that gets you to 400Vp-p) then something is seriously wrong with your
power supply or measurement technique, or you don't have a good ground
between the amp and the scope.

Regards,
Tim

<SNIP>
Thanks Tim. That was just the sort of advice I was looking for. I
don't have a lot of experience with oscilloscopes and every time I use
mine I need to make sure I'm very careful to get everything set
correctly.
Eric

 

[Tim R]

I'm sure you intended humor but I am appalled you buy beer in bottles.

Light is the enemy of beer, and the better beers are the more fragile.

If you like that nasty skunky taste, okay; but we real beer drinkers buy in cans.

https://munchies.vice.com/en_us/article/xy7vn4/this-is-why-your-beer-tastes-skunky

 

[Ralph Mowery]

In article <soe8vdt7b4ud67b6q6pkn11ct68krrf1i7@4ax.com>,
etpm@whidbey.com says...

I have bought a $ 300 Hantek scope. It is suppose to be good to 200 MHz
and rated for 600 volts peak. Good thing about it, you can set the
screen up for waveform and digital volt meter. YOu see the waveform and
good resolution of voltage at the same time.

Sometimes it may be better or easier to just isolate the test equipment
from the ground and not the unit under test. I don't know how much the
solid scope draws without going to check, but it could probalby be
powered by 2 transformers of 24 volts at 2 amps or so placed back to
back.

I think I need to take a look at one of those.
Thanks,
Eric

Look into it at this company. They often put it on sale and with free
shipping. I bought one there and a friend did also. They seem to be
fine scopes for the price, especilally if you have an analog scope to
use. They sell several other scopes of the same brand along with many
other items at a good price.

 

On Tuesday, 20 November 2018 16:34:52 UTC, et...@whidbey.com wrote:

On Tue, 20 Nov 2018 08:21:51 +0800, Rheilly Phoull

An expert who has no knowledge of voltage dividers

I know what a voltage divider is and have used them for some DC stuff,
but I don't know enough about AC signals to know if one would affect
the way the signal looks on a scope.
TYhjanks,
Eric

it won't change the signal, except for very high frequencies far above audio


NT

 

On Tuesday, 20 November 2018 16:46:14 UTC, et...@whidbey.com wrote:

On Tue, 20 Nov 2018 02:03:08 -0800 (PST), tabbypurr wrote:
On Tuesday, 20 November 2018 06:18:38 UTC, Phil Hobbs wrote:
On 11/19/18 7:01 PM, etpm@whidbey.com wrote:
Hey all youse 'scope gurus,

Anyway, do I need a different 'scope to to measure accurately what
is going on inside vacuum tube equipment?

no

If you all think another 'scope should be in my future I would love
some advice. Since this is a hobby I don't wanna spend a lot of money
on yet another toy, er tool. So a used 'scope is fine with me. I love
my used TEK 465B.

Everybody should have another scope now and again. I have 11 at the
moment, which is none too many.

(On average I pay about 3 cents on the dollar, which makes new scopes an
easier sell.)

Cheers

Phil Hobbs

If you're going to get one you don't need, consider making it a pocket scope. Quite handy, even with modest specs.


NT
I have been looking at some on eBay. Do you have any suggestions?
Thanks,
Eric

Not really, totally depends what you want


NT

 

[Phil Hobbs]

On 11/20/18 10:02 AM, Ralph Mowery wrote:

In article <45a5d682-139d-4aaa-9ca2-b4d9243ea05e@googlegroups.com>,
tabbypurr@gmail.com says...

Maybe it's time to make some new tube testers.

While we're here, an iso won't help if you connect an earthed scope to the thing. It will bite you if you touch, and that's how HT is.




It is usually easier to just pop in a good tube instead of testing
unless looking for a matched set.

I have bought a $ 300 Hantek scope. It is suppose to be good to 200 MHz
and rated for 600 volts peak. Good thing about it, you can set the
screen up for waveform and digital volt meter. YOu see the waveform and
good resolution of voltage at the same time.

Sometimes it may be better or easier to just isolate the test equipment
from the ground and not the unit under test. I don't know how much the
solid scope draws without going to check, but it could probalby be
powered by 2 transformers of 24 volts at 2 amps or so placed back to
back.

Does it have a separate A/D for the voltmeter, or is it stuck with 8-bit
resolution?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

On 11/20/18 11:52 AM, etpm@whidbey.com wrote:

On Tue, 20 Nov 2018 02:03:08 -0800 (PST), tabbypurr@gmail.com wrote:

On Tuesday, 20 November 2018 06:18:38 UTC, Phil Hobbs wrote:
On 11/19/18 7:01 PM, etpm@whidbey.com wrote:
Hey all youse 'scope gurus,

Anyway, do I need a different 'scope to to measure accurately what
is going on inside vacuum tube equipment?

no

If you all think another 'scope should be in my future I would love
some advice. Since this is a hobby I don't wanna spend a lot of money
on yet another toy, er tool. So a used 'scope is fine with me. I love
my used TEK 465B.

Everybody should have another scope now and again. I have 11 at the
moment, which is none too many.

(On average I pay about 3 cents on the dollar, which makes new scopes an
easier sell.)

Cheers

Phil Hobbs

If you're going to get one you don't need, consider making it a pocket scope. Quite handy, even with modest specs.


NT
I have been looking at some on eBay. Do you have any suggestions?
Thanks,
Eric

My next one might be something with serial decode.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

On Tue, 20 Nov 2018 08:52:58 -0800 (PST), Tim R <timothy42b@aol.com>
wrote:

I'm sure you intended humor but I am appalled you buy beer in bottles.

Light is the enemy of beer, and the better beers are the more fragile.

If you like that nasty skunky taste, okay; but we real beer drinkers buy in cans.

https://munchies.vice.com/en_us/article/xy7vn4/this-is-why-your-beer-tastes-skunky

Yeah, I usually buy beer in cans. More often now good beer is
available in cans. It used to be good local beer was only available in
brown bottles. It is truly amazing how much good beer there is today.
Eric

 

On Tue, 20 Nov 2018 14:25:38 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 11/20/18 11:52 AM, etpm@whidbey.com wrote:
On Tue, 20 Nov 2018 02:03:08 -0800 (PST), tabbypurr@gmail.com wrote:

On Tuesday, 20 November 2018 06:18:38 UTC, Phil Hobbs wrote:
On 11/19/18 7:01 PM, etpm@whidbey.com wrote:
Hey all youse 'scope gurus,

Anyway, do I need a different 'scope to to measure accurately what
is going on inside vacuum tube equipment?

no

If you all think another 'scope should be in my future I would love
some advice. Since this is a hobby I don't wanna spend a lot of money
on yet another toy, er tool. So a used 'scope is fine with me. I love
my used TEK 465B.

Everybody should have another scope now and again. I have 11 at the
moment, which is none too many.

(On average I pay about 3 cents on the dollar, which makes new scopes an
easier sell.)

Cheers

Phil Hobbs

If you're going to get one you don't need, consider making it a pocket scope. Quite handy, even with modest specs.


NT
I have been looking at some on eBay. Do you have any suggestions?
Thanks,
Eric


My next one might be something with serial decode.

Cheers

Phil Hobbs

What does serial decode do?
Thanks,
Eric

 

On Tue, 20 Nov 2018 12:30:07 -0500, Ralph Mowery
<rmowery28146@earthlink.net> wrote:

In article <soe8vdt7b4ud67b6q6pkn11ct68krrf1i7@4ax.com>,
etpm@whidbey.com says...

I have bought a $ 300 Hantek scope. It is suppose to be good to 200 MHz
and rated for 600 volts peak. Good thing about it, you can set the
screen up for waveform and digital volt meter. YOu see the waveform and
good resolution of voltage at the same time.

Sometimes it may be better or easier to just isolate the test equipment
from the ground and not the unit under test. I don't know how much the
solid scope draws without going to check, but it could probalby be
powered by 2 transformers of 24 volts at 2 amps or so placed back to
back.

I think I need to take a look at one of those.
Thanks,
Eric



Look into it at this company. They often put it on sale and with free
shipping. I bought one there and a friend did also. They seem to be
fine scopes for the price, especilally if you have an analog scope to
use. They sell several other scopes of the same brand along with many
other items at a good price.

I think you forgot to include a link.
Eric

 

[Phil Hobbs]

On 11/20/18 6:05 PM, etpm@whidbey.com wrote:

On Tue, 20 Nov 2018 14:25:38 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 11/20/18 11:52 AM, etpm@whidbey.com wrote:
On Tue, 20 Nov 2018 02:03:08 -0800 (PST), tabbypurr@gmail.com wrote:

On Tuesday, 20 November 2018 06:18:38 UTC, Phil Hobbs wrote:
On 11/19/18 7:01 PM, etpm@whidbey.com wrote:
Hey all youse 'scope gurus,

Anyway, do I need a different 'scope to to measure accurately what
is going on inside vacuum tube equipment?

no

If you all think another 'scope should be in my future I would love
some advice. Since this is a hobby I don't wanna spend a lot of money
on yet another toy, er tool. So a used 'scope is fine with me. I love
my used TEK 465B.

Everybody should have another scope now and again. I have 11 at the
moment, which is none too many.

(On average I pay about 3 cents on the dollar, which makes new scopes an
easier sell.)

Cheers

Phil Hobbs

If you're going to get one you don't need, consider making it a pocket scope. Quite handy, even with modest specs.


NT
I have been looking at some on eBay. Do you have any suggestions?
Thanks,
Eric


My next one might be something with serial decode.

What does serial decode do?

It reads out the hex data on a serial bus such as SPI or I2C. Sort of a
poor man's logic analyzer.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Terry Schwartz]

I use a serial decode scope all the time -- to debug vehicle CAN bus transactions. It's more of a rich man's logic analyzer. It can do so much more than a logic analyzer.

Terry

It reads out the hex data on a serial bus such as SPI or I2C. Sort of a
poor man's logic analyzer.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Ralph Mowery]

In article <ts49vd1oo1d69vlef7q1m8hchl4tq7vvvb@4ax.com>,
etpm@whidbey.com says...

Look into it at this company. They often put it on sale and with free
shipping. I bought one there and a friend did also. They seem to be
fine scopes for the price, especilally if you have an analog scope to
use. They sell several other scopes of the same brand along with many
other items at a good price.

I think you forgot to include a link.
Eric

https://www.circuitspecialists.com/digital-storage-oscilloscopes

Yes I did.

 

[Ralph Mowery]

In article <pt1msq$722$1@dont-email.me>,
pcdhSpamMeSenseless@electrooptical.net says...

Does it have a separate A/D for the voltmeter, or is it stuck with 8-bit
resolution?

I don't know how it determins the voltage. It does give the frequency
and time period. Not too sure how accurate it is, but did read a 9 volt
battery to 2 decimal places, but I did not check it with my digital
voltmeter to see how close it was. For all I know it could have been
off half a volt. I don't use it when I want a ver accurate volt
measurment,but as I am just using it for hobby work, good enough for me
most of the time. This is not a high dollar test instrument.

 

[Phil Allison]

Tim Schwartz wrote:

Eric,

I'd suggest using a voltmeter (analog or digital, whatever you
prefer)for the DC voltage measurements. I like my old Heathkit VTVM for
troubleshooting, as you are unlikely to cause any serious damage to the
meter, as could happen with a digital.

** Yes - plus VTVMs have wide frequency response on the AC ranges unlike the vast majority of hand held DMMs.

The scope you have is all you need, as what you need it for is the AC
part of the waveform. Set the scope to AC coupling at the input and
you'll be looking at the ripple on the supply.

** Ripple voltage on the first filter cap ( after the rectifier) in a PSU looks *sawtooth* shaped - not sine wave. The voltage rises sharply during charging and falls slowly when discharging.

If the ripple exceeds 400 volts (8 divisions at 5 volts each is 40Vp-p
and with a 10x probe that gets you to 400Vp-p) then something is seriously
wrong with your power supply or measurement technique,

** That is a massive understatement !!.

Ripple voltage during normal operation should not be greater than 10% of the DC supply voltage. So, for a 400VDC supply, the p-p ripple seen on a scope should not exceed 40Volts. An AC voltmeter will show about 14V instead, long as there is a cap ( say 0.1uF) in series to block the DC voltage.



.... Phil

 

"I have a TEK 465B oscilloscope and it has served me well until now
diagnosing my CNC equipment. All the voltages I have needed to measure have been below 50 volts. But looking at the 'scope it seems like at the 10x setting on the probes the highest voltage I can measure is 200 volts. That's 4 divisions at 50 volts per division. And that's peak to peak, not RMS. I do have one 20x TEK probe, a P5120, that I used for measuring the mains power, but the voltages inside tube equipment go much higher. "

Get a 100:1 probe. They have them on eBay for less than $20. If you don't like eBay there are alternatives. that will igve you 500V/div. at the highest setting. Don't use it on AC coupling though it takes 10 times as long to settle. Well you can buti t takes 10 times as long to settle.

>"If you all think another 'scope should be in my future I would love some advice. "

The only way a scope would help is if you get an older one that goes up to 20V/div. which would be 200V/div. at 10:1. I keep at least one around just for that. A probe is cheaper unless you want to trade me that 465B for an older Tenma or B&K or something with the higher voltage ranges, but only 15 or 20 MHz bandwidth.

>"Now before everybody starts giving me advice about high voltages
and all that I need everybody to know that I am expert and know all
there is to know about working with high voltages."

Famous last words, right up there with "y'all watch this" but I am not your Mommy. I can tell you this, you ain't been shocked until you been shocked by tube equipment. If you really want some thrills try the cathode of a damper tube in a color TV from the 1960s.

>"Don't waste my time telling me to put down my drink before I start working around high voltages."

That is a very foolhardy attitude, you could spill it !

"I always use plastic cups for my drinks when working with
high voltages."

Pussy.

"Oh, and I don't put any salt on the rims of my Bloody
Marys either."

That's a tokillya sunrise you sot.

>"They keep my hands from shaking too much in the morning."

The shakes is not from alcohol withdrawal, it is from mineral deficiencies. Get a comprehensive colloidal supplement and take a shot of that before your eye opener every morning.

"I just watched a video about isolation transformers, how to build
one in a proper enclosure and how to use it properly."

Don't bother with tube equipment unless it is blowing the line fuse. It doesn't like variacs much especially if it has a tube rectifier. Actually if you have selenium rectifiers use a DBT with all the tubes pulled. Also -

https://www.youtube.com/watch?v=P9UjxG8sN1c

>"And if anybody here thinks I could use some more advice about working around high voltages..."

If we don't hear from you anymore we'll figure yes. Update your will.

 

[pfjw@aol.com]

A proper Bloody Mary has a salted rim.

Low potassium will cause cramps and shakes. Oranges, orange Juice, a banana, and so forth will address that issue nicely. V8 juice as well, tomato juice, more so.

Peter Wieck
Melrose Park, PA

 

[Phil Hobbs]

On 11/26/18 9:42 AM, pfjw@aol.com wrote:

A proper Bloody Mary has a salted rim.

Low potassium will cause cramps and shakes. Oranges, orange Juice, a banana, and so forth will address that issue nicely. V8 juice as well, tomato juice, more so.

Peter Wieck
Melrose Park, PA

Yah, all that trace mineral nutritional data is super dodgy. Some grad
student in the '50s measured three bananas from a plot fertilized with
potash, and surprise surprise all bananas became "a good source of
potassium" forever, no matter what soil conditions they're grown in.

Nutrition 'science' is largely a cargo cult.

Cheers

Phil Hobbs