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Hi Chris and anyone else,

As noted by Roger I wrote ps in stead of ns. I saw now that I made this
mistake more often. Hence for easier reference and to avoid further confusion
I repeat my corrected messages here.

Now I confirmed my remarks quoted below, using the 7T11A/7S11 combo in my
7854. Real time range .5 ms/div, speed 200 ns/div. In 7854 analog mode of
course again I only see sparsely scattered dots. But after ACQ (acquire) I get
a nice stored waveform, with correct edge and rise time, exactly as in the
7T11 equivalent time ranges. This works because ACQ continues acquiring until
(almost) all horizontal positions in the stored waveform are filled. With 1024
points per waveform this took many seconds!
BTW I used the square wave output of an FG504. One feature of this function
generator is that rise and fall times can be selected. I chose 200 ns and 150
kHz repetition rate (quite arbitrarily, higher might be better to reduce
jitter). The 200 ns transitions are still nearly linear with sharp corners at
top and bottom, in stead of S-shaped. Very nice.

Albert

On Tue, Dec 18, 2018 at 04:36 PM, Albert Otten wrote:

Hi Chris,
Without quoting here all the previous stuff I like to visit these findings
once more:

The risetime thing is interesting. If I use the 7T11 in real-time mode

with

my S-1 head, the risetime is about 100us.
However, in equivalent-time mode, I can quite easily see the 350ps

risetime

of the head and the waveform looks accurate.

With my least-broken S-2 head, the risetime in real-time mode is

definitely

faster than with the S-1. But the waveform
as seem through the S-2 is definitely not accurate, though in
equivalent-time mode the its risetime is fast (definitely better than

100ps).

In my opinion it's impossible to study these fast rise times in real time
mode. The 7S11 sampling moments are quite random compared to the 7T11 sweep
start moments. Suppose you have the "true" rising edge located somewhere on
the sweep. The fraction of sweeps which show a sample dot on the rising edge
is very small. So you see dots mostly at the bottom and the top line, and
seldom an intermediate dot. Also the last dot in a sweep before the start of
the edge is sampled most often quite some time before the start of the edge.
Similarly the first dot after the edge is mostly much farther to the right

on

the screen. So was my observation at 500 ns/div at the 3rd RT range and 200

ns

rise time. If you look at "some distance" then you might have the impression
that the rise time is rather long. If you look at how far the bottom line

dots

appear to the right and the top line dots to the left, then you notice just

a

small time gap between those two, more realistic for the true rise time.

Albert

Hi Chris,
Without quoting here all the previous stuff I like to visit these findings
once more:

The risetime thing is interesting. If I use the 7T11 in real-time mode with
my S-1 head, the risetime is about 100us.
However, in equivalent-time mode, I can quite easily see the 350ps risetime
of the head and the waveform looks accurate.

With my least-broken S-2 head, the risetime in real-time mode is definitely
faster than with the S-1. But the waveform
as seem through the S-2 is definitely not accurate, though in
equivalent-time mode the its risetime is fast (definitely better than 100ps).

In my opinion it's impossible to study these fast rise times in real time
mode. The 7S11 sampling moments are quite random compared to the 7T11 sweep
start moments. Suppose you have the "true" rising edge located somewhere on
the sweep. The fraction of sweeps which show a sample dot on the rising edge
is very small. So you see dots mostly at the bottom and the top line, and
seldom an intermediate dot. Also the last dot in a sweep before the start of
the edge is sampled most often quite some time before the start of the edge.
Similarly the first dot after the edge is mostly much farther to the right on
the screen. So was my observation at 500 ns/div at the 3rd RT range and 200 ns
rise time. If you look at "some distance" then you might have the impression
that the rise time is rather long. If you look at how far the bottom line dots
appear to the right and the top line dots to the left, then you notice just a
small time gap between those two, more realistic for the true rise time.

Albert

Hi Chris,
Without quoting here all the previous stuff I like to visit these findings
once more:

The risetime thing is interesting. If I use the 7T11 in real-time mode with
my S-1 head, the risetime is about 100us.
However, in equivalent-time mode, I can quite easily see the 350ps risetime
of the head and the waveform looks accurate.

With my least-broken S-2 head, the risetime in real-time mode is definitely
faster than with the S-1. But the waveform
as seem through the S-2 is definitely not accurate, though in
equivalent-time mode the its risetime is fast (definitely better than 100ps).

In my opinion it's impossible to study these fast rise times in real time
mode. The 7S11 sampling moments are quite random compared to the 7T11 sweep
start moments. Suppose you have the "true" rising edge located somewhere on
the sweep. The fraction of sweeps which show a sample dot on the rising edge
is very small. So you see dots mostly at the bottom and the top line, and
seldom an intermediate dot. Also the last dot in a sweep before the start of
the edge is sampled most often quite some time before the start of the edge.
Similarly the first dot after the edge is mostly much farther to the right on
the screen. So was my observation at 500 ps/div at the 3rd RT range and 200 ps
rise time. If you look at "some distance" then you might have the impression
that the rise time is rather long. If you look at how far the bottom line dots
appear to the right and the top line dots to the left, then you notice just a
small time gap between those two, more realistic for the true rise time.

Albert

Dear List,

could you please help me, which probes fit the 7A14 current amplifier ?

Thank you

Jan


-- Mit freundlichen Gruessen---best regards----cordialement

Dipl.-Ing. Jan Philipp Wuesten (Telefon direkt: 04882-6054551)

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It's fairly common on CL too- if you want the high end/useful goodies in
a freebie pile, you have to take the whole pile.
-Dave
On Tuesday, December 18, 2018, 5:49:14 PM PST, EricJ via Groups.Io
<wyzkydd2358@...> wrote:

It's pretty easy to understand really. If they want to capitalize on
getting some free stuff then they have to do the work of clearing out the
rest. If nobody is willing to do that then you don't have a whole lot more
work to do than you already did.
--Eric
Sent from my Samsung Galaxy smartphone.

My plan is simple.? Anybody can have anything they want.? But you have to
take it all.

-Bob

On Sat, Dec 8, 2018 at 5:36 PM <toby@...> wrote:

On 2018-12-08 2:38 PM, oliver johnson via Groups.Io wrote:

Hi all I for one have more scopes than i can or will ever use , but for

some strange reason i keep getting them . For me it just fixing them that i
enjoy and once fixed it goes in the pile that i have , speaking of pile i
am looking for one last tek to complete my dual beam collection,? 7844 is
the last tek needed for dual beam collection,? if anyone has one reasonable
please let me know,? thanks and keep the hobby going .


This thread really makes me wonder how many collectors have a succession
plan for when we can't take care of them all any more.

How many have lined up a Will, or executor who will successfully be able
to rehome your collection to a museum or suitably responsible individual?

The "wife seeks to get rid of 97 of husband's instruments by Sunday,
local pickup only", that we see semi-regularly now, is far from the
worst case scenario.

--Toby


Disclaimer: I haven't

? ? On Sat, Dec 8, 2018 at 1:39 PM, TomC<tomc@...> wrote:? On

12/7/2018 3:15 PM, Craig Sawyers wrote:

Now just what do I do if I have to display more than 12 waveforms at

once ?

Ah - you can do that with a single 7844

How?

My plan is simple.? Anybody can have anything they want.? But you have to
take it all.

-Bob

On Sat, Dec 8, 2018 at 5:36 PM <toby@...> wrote:

On 2018-12-08 2:38 PM, oliver johnson via Groups.Io wrote:

Hi all I for one have more scopes than i can or will ever use , but for

some strange reason i keep getting them . For me it just fixing them that i
enjoy and once fixed it goes in the pile that i have , speaking of pile i
am looking for one last tek to complete my dual beam collection,? 7844 is
the last tek needed for dual beam collection,? if anyone has one reasonable
please let me know,? thanks and keep the hobby going .


This thread really makes me wonder how many collectors have a succession
plan for when we can't take care of them all any more.

How many have lined up a Will, or executor who will successfully be able
to rehome your collection to a museum or suitably responsible individual?

The "wife seeks to get rid of 97 of husband's instruments by Sunday,
local pickup only", that we see semi-regularly now, is far from the
worst case scenario.

--Toby


Disclaimer: I haven't

? ? On Sat, Dec 8, 2018 at 1:39 PM, TomC<tomc@...> wrote:? On

12/7/2018 3:15 PM, Craig Sawyers wrote:

Now just what do I do if I have to display more than 12 waveforms at

once ?

Ah - you can do that with a single 7844

How?

My plan is simple. Anybody can have anything they want. But you have to
take it all.

-Bob

On Sat, Dec 8, 2018 at 5:36 PM <toby@...> wrote:

On 2018-12-08 2:38 PM, oliver johnson via Groups.Io wrote:

Hi all I for one have more scopes than i can or will ever use , but for

some strange reason i keep getting them . For me it just fixing them that i
enjoy and once fixed it goes in the pile that i have , speaking of pile i
am looking for one last tek to complete my dual beam collection, 7844 is
the last tek needed for dual beam collection, if anyone has one reasonable
please let me know, thanks and keep the hobby going .


This thread really makes me wonder how many collectors have a succession
plan for when we can't take care of them all any more.

How many have lined up a Will, or executor who will successfully be able
to rehome your collection to a museum or suitably responsible individual?

The "wife seeks to get rid of 97 of husband's instruments by Sunday,
local pickup only", that we see semi-regularly now, is far from the
worst case scenario.

--Toby


Disclaimer: I haven't

On Sat, Dec 8, 2018 at 1:39 PM, TomC<tomc@...> wrote: On

12/7/2018 3:15 PM, Craig Sawyers wrote:

Now just what do I do if I have to display more than 12 waveforms at

once ?

Ah - you can do that with a single 7844

How?

On 2018-12-08 2:38 PM, oliver johnson via Groups.Io wrote:

Hi all I for one have more scopes than i can or will ever use , but for

some strange reason i keep getting them . For me it just fixing them that i
enjoy and once fixed it goes in the pile that i have , speaking of pile i
am looking for one last tek to complete my dual beam collection, 7844 is
the last tek needed for dual beam collection, if anyone has one reasonable
please let me know, thanks and keep the hobby going .


This thread really makes me wonder how many collectors have a succession
plan for when we can't take care of them all any more.

How many have lined up a Will, or executor who will successfully be able
to rehome your collection to a museum or suitably responsible individual?

The "wife seeks to get rid of 97 of husband's instruments by Sunday,
local pickup only", that we see semi-regularly now, is far from the
worst case scenario.

--Toby


Disclaimer: I haven't

On Sat, Dec 8, 2018 at 1:39 PM, TomC<tomc@...> wrote: On

12/7/2018 3:15 PM, Craig Sawyers wrote:

Now just what do I do if I have to display more than 12 waveforms at

once ?

Ah - you can do that with a single 7844

How?

+13volts

You need to get a better manual copy ...I know just the place
Dave
manuals@...

On 12/17/2018 9:14 PM, lop pol via Groups.Io wrote:

Im still troubleshooting my 468. My schematic is blurry and I was wondering

if anyone could tell me the proper voltage at the base of Q958 and Q987A on
the A15 board. I have 15V on one side of R971 but he other side is wildly
fluctuating between 9V and 12V I don't think thats right. Thanks guys.

--
Dave
Manuals@...
www.ArtekManuals.com