Date   

Re: GPIB board for calibrating AM503B, or alternatives?

Jared Cabot
 

I've had a look through the document and it makes sense so far, but I just have to figure out all this firmware business and sending the right commands in the right format... I tend to program with solder rather than a keyboard, so it's definitely a learning curve for me. :)

My script will be rather large once it's done (It's sprouting a command line UI) but it can certainly be distributed with the document.
I might look at making a github repository for it soon once I'm not completely embarrassed by the code. hahaha.


Regards,
Jared


Re: Tektronix 2465B Square wave noise on active readout. #photo-notice

Jean-Paul
 

Hello: Bravo, what did it cost?

On turn on does it pass self test or indicate errors?

check the A5 control board on the side: Dallas 1227 NVRAM internal battery may be dead and loss of CAL constants.


SMD ELCO caps leak acid and corrode the PCB especially in the control area.

See many long threads on this forum and EEVBLOG, search 2465B A5, NVRMA, SMD caps.


Bon Chance,

Jon


Photo 577D1CRTFLASH.gif updated #photo-notice

TekScopes@groups.io Notification <noreply@...>
 

The following photos have been updated in the 577 D1 CRT flash album of the TekScopes@groups.io group.

By: DW <wilson2115@...>


547 Restoration conundrum #photo-notice

Jason A.
 

Hello fellow Tek fans,

I'm in the midst of what are hopefully some of the finishing touches to my 547 restoration and I've hit one thing that is perplexing me as I have found no mention of this specific issue - and hopefully I'm not just missing the correct search term. After some extremely helpful recommendations from Chuck on the HV section of my 547, I have eliminated all but one of my display oddities. Everything is leaning slightly up and to the left. See photos here:

https://groups.io/g/TekScopes/album?id=264243

A little history - until recently the geometry was seriously compromised on my 547. I replaced the HV diodes with solid state ones per this forum and TekWiki's mention of it being a recommendation from the late-great Jim Williams, finishing out that modification with replacing the 56K-ohm resistor R803 up to a 68K to keep the 12AU7's plate at the correct voltage. I just tonight finished replacing the last 2 resistors on the HV section of the 547 and that has made an amazing difference in both geometry and trace definition/focus/clarity. The final adjustment I would like to make is to get rid of the display-wide slant.

If anyone has any recommendations on what I am missing, I would love to hear from you.

Thanks everyone and especially Chuck for helping point me in the right direction on the resistors.

Jason


Re: Tek 577 Step Gen & Volt Div knobs skirt pictures needed

Stefan
 

Thanks, Andy. It may be best to let Roger scale the image when printing, but I can do it, too. I’m happy with either measure.

-Stefan


Re: GPIB board for calibrating AM503B, or alternatives?

 

Hi Jared,

Set the bus speed to 100kHz. That was the original definition by Philips Semiconductor for the I2C-Bus.
This value is also given in the datasheet of the PCF8570.

As I have already written, my "Bus Pirate" is on the way from China to Switzerland.
As soon as it arrives, I can send you the commands.

Have you been able to read through the document in the meantime?
I think after you've written a script, we should include it in the document as an example.

Best regards
Rico


Re: Favor

 

DONE

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Paul
Amaranth
Sent: Monday, May 17, 2021 12:44 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Favor

This is a troll to collect valid email ids.

Maybe put felix1063@comcast.net on moderation?

Paul

On Mon, May 17, 2021 at 03:31:04PM -0400, aldue wrote:
We need details of requested favor. thank you, gary dirkse

On Mon, May 17, 2021 at 12:50 PM J. chang <felix1063@comcast.net> wrote:

- This mail is in HTML. Some elements may be ommited in plain text. -

How are you doing? I need a personal favor.

Please email me back.


--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@AuroraGrp.Com | Unix/Linux - We don't do windows







--
Dennis Tillman W7pF
TekScopes Moderator


Tektronix 2465B Square wave noise on active readout. #photo-notice

@Antonio90
 

Greetings,

I'm new to the group, and a beginner electronics hobbyist. Coming here looking for help repairing a Tek scope. I see most people have problems related to the power supply but, as far as I've been able to tell, it is working kind of fine.
It might have been repaired or refurbished already: It had a missing screw on the top metal shielding, and the caps seem new. No surface mount electrolytic either.

So, I recently bought a Tek 2465B for a very low price, it was sold as "good condition" and as working. I had the opportunity to test it for a brief time, but not knowing almost anything about the operation of this scope, I just checked the probe compensation square wave and fed a couple of waveforms from my AD2. It seemed to work fine, and apart from a slightly bent pot under the screen and a somewhat noisy fan, the apparent condition was good.

Then, testing it more thoroughly at home, I found a problem with the readout data and cursors, it is shown in the following video:

https://youtu.be/rFkmVqaTmHY

The problems are as follows:

1 - Readout intensity potentiometer in the "off" state: It works fine. Trace is stable, and the readings are more or less accurate.

2 - Pot turned clockwise, "scale factors on": The trace depicts a waveform that looks like a digital signal, an irregular square wave.

3 - Pot turned counter-clockwise "scale factors off":
- Measurement lines on: The same waveform as in point 2.
- Measurement lines off: A normal squarewave.

4 - Auto button pressed: Trace disappears on the upper side of the screen, readout and cursors activate. It can be moved down without problems, but the readout intensity has to be turned to "off" again to display the input waveform.

Some notes:
- This happens only to channels 1 and 2. Channels 3 and 4 work well with auto set up and everything else.
- Measured voltages are within specs according to my cheap DMMs (2 anengs and one WHA5000 something).
- Photos added in linked album.

Album: https://groups.io/g/TekScopes/album?id=264175

Also, don't know if it's relevant, but there is a jumper resistor and a small wire on U975 that goes under the ribbon connectors on the side of the scope.
I tried to look for U2810 and U2900, but the board in the service manual shows an earlier version that looked like an addon card, don't really know where it is on my scope.

If someone could help pointing in any direction to troubleshoot, I would be really grateful. Maybe this is a documented fault, but I haven't been able to find this reproduced in any of the forum threads or videos I looked at.

Thank you very much,
Antonio.


Re: Looking for sensitive audio RMS meter

 

Gentlemen,
Please wrap up your discussion of audio RMS meters.
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of cheater cheater
Sent: Monday, May 17, 2021 8:51 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Looking for sensitive audio RMS meter

In this example, why isn't the +15 dBm signal nominal?

When defining the max singnal, why stop at 5% distortion? Why not 50% distortion?

On Mon, May 17, 2021 at 7:03 AM Jean-Paul <jonpaul@ix.netcom.com> wrote:

Bob and Cheater:

In audio, signal analysis, video, here are my definitions, of course open to your comments!


Noise floor is the measured RMS with no signal and the device terminated in desired Zo, eg place a 50 Ohm term on the BNC of a scope plugin, view the noise floor and measure RMS.

Signal to Noise Ratio: SNR:

Ratio of a standard or nominal signal level to the noise floor, eg a -10 dBm normal signal level and -90 dBm noise floor gives SNR 80 dB. Of course one must define the nominal signal level!

Dynamic range is the max signal level before a specified distortion eg 1% THD, or a certain 3rd order IM, to the noise floor.
In the same example above, for a -10 dBm nominal, the system has 5% distortion with a +15 dBm signal, thus the dynamic range is +15 (-) -90 = 105 dBm.

Enjoy,


Jon














--
Dennis Tillman W7pF
TekScopes Moderator


Re: Tek 577 Step Gen & Volt Div knobs skirt pictures needed

Andy Warner
 

Nice job, Stefan. Looks great.
I can take some critical diameter measurements to help scale it, do you
prefer metric or imperial ?

On Mon, May 17, 2021 at 11:29 Stefan <Sscandizzo@comcast.net> wrote:

Hi Roger,

I've added an image to the photo folder. Is this something you can use?

-Stefan





--
Andy


Re: Favor

Paul Amaranth
 

This is a troll to collect valid email ids.

Maybe put felix1063@comcast.net on moderation?

Paul

On Mon, May 17, 2021 at 03:31:04PM -0400, aldue wrote:
We need details of requested favor. thank you, gary dirkse

On Mon, May 17, 2021 at 12:50 PM J. chang <felix1063@comcast.net> wrote:

- This mail is in HTML. Some elements may be ommited in plain text. -

How are you doing? I need a personal favor.

Please email me back.

--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@AuroraGrp.Com | Unix/Linux - We don't do windows


Re: Favor

aldue
 

We need details of requested favor. thank you, gary dirkse

On Mon, May 17, 2021 at 12:50 PM J. chang <felix1063@comcast.net> wrote:

- This mail is in HTML. Some elements may be ommited in plain text. -

How are you doing? I need a personal favor.

Please email me back.






Re: Looking for sensitive audio RMS meter

Bob Albert
 

The amount of distortion is, of course, arbitrary.  However, for communications purposes, 5% is often considered the most acceptable.  Additionally, the level required for 10% or 15% distortion is very close to that for 5% so it's not a big deal.
For high fidelity audio, the acceptable distortion would be much less, say 1%.
How offensive a certain amount of distortion would be, depends on the sort of distortion.  Hum and noise and even or odd harmonics, etc.
Bob

On Monday, May 17, 2021, 09:35:40 AM PDT, Roy Thistle <roy.thistle@mail.utoronto.ca> wrote:

On Sat, May 15, 2021 at 12:54 PM, Jean-Paul wrote:


Batter my heart, three personed God
I think you mean the 17th century Metaphysical poet John Donne... as in "Any man’s death diminishes me, for I am involved in mankind."  ... and from which, and the same work quoted... Nobel Laureate Ernest Hemingway took the title of his novel... "For Whom the Bell Tolls."

--
Roy Thistle


Re: Looking for sensitive audio RMS meter

Roy Thistle
 

On Sat, May 15, 2021 at 12:54 PM, Jean-Paul wrote:


Batter my heart, three personed God
I think you mean the 17th century Metaphysical poet John Donne... as in "Any man’s death diminishes me, for I am involved in mankind." ... and from which, and the same work quoted... Nobel Laureate Ernest Hemingway took the title of his novel... "For Whom the Bell Tolls."

--
Roy Thistle


Re: Tek 577 Step Gen & Volt Div knobs skirt pictures needed

Stefan
 

Hi Roger,

I've added an image to the photo folder. Is this something you can use?

-Stefan


Re: Looking for sensitive audio RMS meter

 

In this example, why isn't the +15 dBm signal nominal?

When defining the max singnal, why stop at 5% distortion? Why not 50%
distortion?

On Mon, May 17, 2021 at 7:03 AM Jean-Paul <jonpaul@ix.netcom.com> wrote:

Bob and Cheater:

In audio, signal analysis, video, here are my definitions, of course open to your comments!


Noise floor is the measured RMS with no signal and the device terminated in desired Zo, eg place a 50 Ohm term on the BNC of a scope plugin, view the noise floor and measure RMS.

Signal to Noise Ratio: SNR:

Ratio of a standard or nominal signal level to the noise floor, eg a -10 dBm normal signal level and -90 dBm noise floor gives SNR 80 dB. Of course one must define the nominal signal level!

Dynamic range is the max signal level before a specified distortion eg 1% THD, or a certain 3rd order IM, to the noise floor.
In the same example above, for a -10 dBm nominal, the system has 5% distortion with a +15 dBm signal, thus the dynamic range is +15 (-) -90 = 105 dBm.

Enjoy,


Jon









Re: Need a CT-3 trigger pick-off for the lab.

Eric
 

Doesn’t look like it unfortunately. It appears that the VP-2 is a impedance matching coupler for the S-3 sampling unit which is 75 Ohms. The CT-3 is a 50 ohm pass through with a 10X of attenuation at the pickoff point. In reading the calibration document a little more closely it looks like all this is doing is using a CT-3 to make a small signal out of an sg-503 for use in the trigger adjustment of the 465. You need to make the trigger adjustments around 20 mv of signal at 10 Mhz. If this is truly the case and all that the CT-3 is used for then I have something in the lab already that will cover this signal. My HP 8657A can easily generate these clean and low level signals so I might be able to get this I think the process is adjust the trigger to fire at 25mV, no trigger at 20mV

Eric

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of snapdiode via groups.io
Sent: Sunday, May 16, 2021 9:31 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Need a CT-3 trigger pick-off for the lab.

Would a VP-2 work as well? The difference between a CT and VP seems not too clear to me even after reading the manuals.


Re: GPIB board for calibrating AM503B, or alternatives?

Jared Cabot
 

I've been playing with batch scripts over the weekend, and am successfully initialising the Bus Pirate into I2C mode and have a menu system working in command line.
I hope to be able to read and write values next, then I can add that to the script for easy reprogramming.

A few questions:
What speed should I set the I2C bus to?
What commands did you use on the Bus Pirate to successfully write to the AM503B?


Thanks!


Re: Looking for sensitive audio RMS meter

Jean-Paul
 

Bob and Cheater:

In audio, signal analysis, video, here are my definitions, of course open to your comments!


Noise floor is the measured RMS with no signal and the device terminated in desired Zo, eg place a 50 Ohm term on the BNC of a scope plugin, view the noise floor and measure RMS.

Signal to Noise Ratio: SNR:

Ratio of a standard or nominal signal level to the noise floor, eg a -10 dBm normal signal level and -90 dBm noise floor gives SNR 80 dB. Of course one must define the nominal signal level!

Dynamic range is the max signal level before a specified distortion eg 1% THD, or a certain 3rd order IM, to the noise floor.
In the same example above, for a -10 dBm nominal, the system has 5% distortion with a +15 dBm signal, thus the dynamic range is +15 (-) -90 = 105 dBm.

Enjoy,


Jon


Re: Tek 577 Step Gen & Volt Div knobs skirt pictures needed

Andy Warner
 

Typo in last post i said “yellow numbers”, they are of course, clear and
backlit when the lamp is on.

On Sun, May 16, 2021 at 22:03 Andy Warner <andyw@pobox.com> wrote:

I measure all three knob skirts at 1.482” outside diameter (doesn’t seem to
be around number in metric either.)
I suspect we could use 1.5” without serious problem, although the alignment
of the yellow numbers with the lamp lens will be tricky.
If I remove them again to try and take perfect photos, I will try and
figure out the inner and outer diameter of the alternate markings used when
the lamp is on.

On Sun, May 16, 2021 at 16:39 Stefan <Sscandizzo@comcast.net> wrote:

Hi Roger,

From the photos posted, new dial faces can be created. I would need to
know the true diameter of each dial (3 of them?) and the best example of
the gold color. I would recommend the files be .pdf (photoshop document
file) for its universal format.

These would not be touched up photos, but rather new illustrations with
no
distortions.

Best,
Stefan





--
Andy





--
Andy

4661 - 4680 of 187119