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

On 20/11/2018 8:01 am, wrote:
Hey all youse 'scope gurus,
I'm gonna be getting a new and a used tube amplifier. The new one
is on the way and the used one is in my neighbor's garage. He still
needs to dig it out so I don't know anything about it except that has
tubes in it.
If the new one doesn't come with a schematic then right off the bat
I want to draw one so I can learn more about vacuum tube audio amp
workings. If I have to draw a schematic then I will put in the actual
values of the passives as well as the marked values. And I want to
measure the voltages in the circuit as well and put them into the
schematic. If the old one needs a schematic as well then if I can't
find one online I'll need to give it the same treatment as the new
one. If I do have schematics then all I will need to do is the
measurements and write them down. So....
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.
I have been watching YouTube videos about vacuum tube equipmet and
have learned a lot so far. "Uncle Doug" has several videos that have
taught me a lot. Maybe it's because he used to be a teacher I am
learning so much.
Anyway, do I need a different 'scope to to measure accurately what
is going on inside vacuum tube equipment? Should I just look for
different probes with even more attenuation? I certainly don't need
the 100 MHz bandwidth that the 465B has for working with audio
equipment.
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.
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. Don't waste my time
telling me to put down my drink before I start working around high
voltages. I always use plastic cups for my drinks when working with
high voltages. Oh, and I don't put any salt on the rims of my Bloody
Marys either. And no cans of beer either, only glass bottles. Safety
first. As an expert I know alcoholic drinks are good. They keep my
hands from shaking too much in the morning. And I don't like smoking
pot. I figure I'm just as expert as some other self professed experts
here who don't need any extraneous advice.
I just watched a video about isolation transformers, how to build
one in a proper enclosure and how to use it properly. So even though I
have the isolated variac I think I'll make a 1:1 isolation xmfr too
with a little more ampacity. And if anybody here thinks I could use
some more advice about working around high voltages I welcome it and
will certainly take heed.
Thanks,
Eric


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

On Tuesday, 20 November 2018 16:34:52 UTC, 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