### Author Topic: Can anybody explain me really how do works the time base of HP scopes 1740A and  (Read 10845 times)

0 Members and 1 Guest are viewing this topic.

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #25 on: February 29, 2016, 03:58:18 am »
New photo that I think has 12 cycles:
« Last Edit: February 29, 2016, 04:00:34 am by SAUL BRITTO »
Thank You, for all earth.

#### rf+tech

• Frequent Contributor
• Posts: 274
• Country:
• Miracle repairs performed daily
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #26 on: February 29, 2016, 04:10:51 am »
Saul,

The photo actually shows 12.5 cycles across 10 divisions.

Look at the time marks at the arrows added to your photo.

RF+ Tech

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #27 on: February 29, 2016, 04:11:41 am »
P= 24000000 x 0.00005= 1200 is it right? IF IT IS NOT RIGHT I see at least a 12 ratio,then on the anterior image there is an error of 5 cycles to more. Right?
« Last Edit: February 29, 2016, 04:48:12 am by SAUL BRITTO »
Thank You, for all earth.

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #28 on: February 29, 2016, 04:15:15 am »
Saul,

The photo actually shows 12.5 cycles across 10 divisions.

Look at the time marks at the arrows added to your photo.

RF+ Tech

Then I have to count that half cycle on the begin and on the end,how can I fix this rf+tech?
Thank You, for all earth.

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #29 on: February 29, 2016, 04:18:08 am »
Looks like after the sweep vernier fix it is a bit better.
« Last Edit: February 29, 2016, 04:20:30 am by SAUL BRITTO »
Thank You, for all earth.

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #30 on: February 29, 2016, 05:35:10 am »
I  am reading about this calibration but I still don't have a time marker,can I fix this problem with frequency counter and a good function generator?
Thank You, for all earth.

#### rf+tech

• Frequent Contributor
• Posts: 274
• Country:
• Miracle repairs performed daily
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #31 on: March 01, 2016, 03:31:43 pm »
Saul,

Before jumping into sweep calibration, it is best to know some details about the accuracy of available signals.

What is the source of the 24 MHz signal? How accurate is this signal? Is it crystal controlled?

And the same about your function generator - how accurate is this? Is it synthesized or free running? Do you have a frequency counter?

Also, I see from your posts that you are having difficulty measuring time with an oscilloscope. What is to the left of the first vertical line is not counted.

Go back to the 24 MHz signal as shown in the photo with red arrows.
Position the bottom peak of the first cycle exactly on the first vertical display line.
Move the vertical position up so the bottom peaks are on the center line.
Count 12 bottom peaks and read the scale.
From the photo, this looks like 9.5 or 9.6 divisions.
How many divisions do you measure?
Now turn the sweep vernier from right to left.
Do you see many more cycles?
Turn the sweep vernier to the right (CAL position).

RF+ Tech

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #32 on: March 01, 2016, 10:47:55 pm »
Ok I will do it.
Thank You, for all earth.

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #33 on: March 02, 2016, 12:24:54 am »
Saul,

Before jumping into sweep calibration, it is best to know some details about the accuracy of available signals.

What is the source of the 24 MHz signal? How accurate is this signal? Is it crystal controlled?

And the same about your function generator - how accurate is this? Is it synthesized or free running? Do you have a frequency counter?

Also, I see from your posts that you are having difficulty measuring time with an oscilloscope. What is to the left of the first vertical line is not counted.

Go back to the 24 MHz signal as shown in the photo with red arrows.
Position the bottom peak of the first cycle exactly on the first vertical display line.
Move the vertical position up so the bottom peaks are on the center line.
Count 12 bottom peaks and read the scale.
From the photo, this looks like 9.5 or 9.6 divisions.
How many divisions do you measure?
Now turn the sweep vernier from right to left.
Do you see many more cycles?
Turn the sweep vernier to the right (CAL position).

RF+ Tech

Yes it is a crystal controlled oscillator.
Thank You, for all earth.

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #34 on: March 02, 2016, 12:30:01 am »
I have done these adjustments and got it better,but when a change the sweep time see small differences:
http://i65.tinypic.com/2z80vp3.jpg
« Last Edit: March 02, 2016, 05:42:58 am by SAUL BRITTO »
Thank You, for all earth.

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #35 on: March 02, 2016, 12:36:37 am »
1uSEC  I use 1mhz, 10uSEC 100KHZ and so on but,when I change the time to a near time I see that it does not keep completely stable there is a small difference
Thank You, for all earth.

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #36 on: March 02, 2016, 01:13:08 am »
I'm dabbing ice with this FG.
Thank You, for all earth.

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #37 on: March 02, 2016, 03:15:54 am »
I figure out my FG is deffective,seems a PS problem.
Thank You, for all earth.

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #38 on: March 02, 2016, 03:45:11 am »
Bingo! A cap in leackage and that a leakage wow!!!
Thank You, for all earth.

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #39 on: March 02, 2016, 03:55:14 am »
rf+tech what is the nomenclature for trigger offset on the HP scopes?
Thank You, for all earth.

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #40 on: March 02, 2016, 09:13:27 am »
rf+tech I have new photos and show you later.
« Last Edit: March 02, 2016, 09:15:40 am by SAUL BRITTO »
Thank You, for all earth.

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #41 on: March 02, 2016, 09:17:59 am »
I have done some comparisons with a tek 2220 that I have on the bench and they are very very near.
Thank You, for all earth.

#### tggzzz

• Super Contributor
• Posts: 10499
• Country:
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #42 on: March 02, 2016, 09:23:18 am »
Saul, you might find https://entertaininghacks.wordpress.com/library-2/good-questions-pique-our-interest-and-dont-waste-our-time-2/ helps you in the long term. Not all of the points apply to you, of course!

There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #43 on: March 02, 2016, 10:36:44 am »
I apologize if I made a mistake or bothered in any way but, I'm new in the forum and really need some warnings. But, how to discuss an issue?
Thank You, for all earth.

#### tggzzz

• Super Contributor
• Posts: 10499
• Country:
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #44 on: March 02, 2016, 11:04:53 am »
I apologize if I made a mistake or bothered in any way but, I'm new in the forum and really need some warnings. But, how to discuss an issue?
No problem at all; no apologies necessary. You are honestly trying to learn, and that is good. The reason for pointing to that link is to help you get better answers.

Minor point: learn how to use the "quote" button, so people can understand what you are replying to.

More important point: think before posting, and where appropriate follow some of the guidelines noted on that page. Note that I don't always follow them!
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #45 on: March 02, 2016, 11:25:06 am »
I apologize if I made a mistake or bothered in any way but, I'm new in the forum and really need some warnings. But, how to discuss an issue?
No problem at all; no apologies necessary. You are honestly trying to learn, and that is good. The reason for pointing to that link is to help you get better answers.

Minor point: learn how to use the "quote" button, so people can understand what you are replying to.

More important point: think before posting, and where appropriate follow some of the guidelines noted on that page. Note that I don't always follow them!

Thank you for your advice, was not my intention to cause this kind of event. I will be ever grateful when you advice me about my fails. I confess that I am still a little confused about the right way to act in the forum, will try to improve every day.
Thank You, for all earth.

#### tggzzz

• Super Contributor
• Posts: 10499
• Country:
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #46 on: March 02, 2016, 03:54:31 pm »
I apologize if I made a mistake or bothered in any way but, I'm new in the forum and really need some warnings. But, how to discuss an issue?
No problem at all; no apologies necessary. You are honestly trying to learn, and that is good. The reason for pointing to that link is to help you get better answers.

Minor point: learn how to use the "quote" button, so people can understand what you are replying to.

More important point: think before posting, and where appropriate follow some of the guidelines noted on that page. Note that I don't always follow them!

Thank you for your advice, was not my intention to cause this kind of event. I will be ever grateful when you advice me about my fails. I confess that I am still a little confused about the right way to act in the forum, will try to improve every day.

As I told my daughter, "let's make new mistakes".

Do continue posting and asking questions!
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less

#### SAUL BRITTO

• Frequent Contributor
• Posts: 446
• Country:
• Don't Make a Mistake
##### Re: Can anybody explain me really how do works the time base of HP scopes 1740A and
« Reply #47 on: March 02, 2016, 11:36:30 pm »
I apologize if I made a mistake or bothered in any way but, I'm new in the forum and really need some warnings. But, how to discuss an issue?
No problem at all; no apologies necessary. You are honestly trying to learn, and that is good. The reason for pointing to that link is to help you get better answers.

Minor point: learn how to use the "quote" button, so people can understand what you are replying to.

More important point: think before posting, and where appropriate follow some of the guidelines noted on that page. Note that I don't always follow them!

Thank you for your advice, was not my intention to cause this kind of event. I will be ever grateful when you advice me about my fails. I confess that I am still a little confused about the right way to act in the forum, will try to improve every day.

As I told my daughter, "let's make new mistakes".

Do continue posting and asking questions!

Ok thx.
« Last Edit: March 03, 2016, 04:31:12 am by SAUL BRITTO »
Thank You, for all earth.

Smf