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Date
Re: How can I measure the bandwidth of an audio transformer with the HP8903B ?

 

You will need to match the source and load impedances to get an accurate result. Ideally you should also pass the same DC current through the core as the quiescent current of the amplifier as a DC current will tend to shift the B-H curve of the core, reducing inductance and therefore changing the frequency response. I've done similar with HF transformers in the past.

Thanks
Gavin
Re: How can I measure the bandwidth of an audio transformer with the HP8903B ?

 

Do you have any specs on the transformer?? Like input and output impedances?? What tubes will it be used with?? Output impedance 4/8/16 ohms?
Re: How can I measure the bandwidth of an audio transformer with the HP8903B ?

Gary Johnson
 

To obtain a good measurement of BW in an impedance matching transformer like this, it does indeed need to be tested with correct terminations on both sides. Since the output of your generator is an accurate wideband 600 ohms, you can pad that up with a series resistance to match the transformer's primary. Then terminate the secondary with 8 ohms or whatever load you want. The measurement side of the instrument is hi-Z so it won't load that. If you don't know the impedance of the primary, you can determine that by measuring the open-circuit voltage gain of the transformer at 1 kHz, then take the square of that to get the impedance ratio. Of course, the real world is nothing like this test! Effective impedance at the plates of the tubes is neither flat nor purely resistive, and loudspeaker impedance varies all over the place. I've always considered such a test as a validation of the transformer specs, and it's also useful when making comparisons.

DC bias is of no concern since the push-pull topology applies B+ via a center tap, so the dc fields cancel.?

-Gary NA6O
Re: HP 1727A CRO: Problem with the vertical output amplifier.

 

On Wed, Feb 23, 2022 at 06:05 PM, Alex_03 wrote:
pins 7 and 5 same as U1 pins 12 and 13.

U2 pin 6: 20V
U2 pins 2 and 3: 42V?

Should pin 6 be that high? obviously it is outputting current to the 15V rail, about 155mA, but I don't know.?
--------
These voltages look pretty much on target. Take a look at the voltages on 1725A schematic that uses the same ICs. I agree it is an interesting choice to back feed +15V supply. It saves some power by re-using the current but it is unusual.?

Nothing looks off in DC sense. Your scope waveforms were with AC coupling, it is possible that there is was a large DC signal during the scope capture. What are you using as the input signal (if calibrator output why is it triangle shaped)??

I recommend looking at U1 pins 3/6, 4/5, 12/13 with DC coupling on your scope.?

Ozan
Re: massive attachments

 

These days, with the huge pixel counts on "modern" smartphones, pics do often carry very few information compared to the size of the file.

A great tool is "ImageOptim". Its free. Just drop a pic on it, and its size can be reduced up to a factor of 10 or more, often without visible degradation to the pic.

cheers
Martin
Re: How can I measure the bandwidth of an audio transformer with the HP8903B ?

 

I agree with Pete. You can make some estimates with small signal conditions, but the real answer lies in what it does in an actual circuit. I think it's safe to assume it will work according to its specs (if you have them), and it's probably not worth worrying about measuring and guessing based on it viewed as a lone component. If you actually build a PA with it, in a real circuit, then you can use all sorts of instrumentation to see how well it works, and tweak the design as required.

Ed
Re: How can I measure the bandwidth of an audio transformer with the HP8903B ?

 

I don't know the real answer, but wouldn't it be necessary to drive the transformer from an impedance that matches the push-pull tube setup, including the source impedance *and* the DC current and such? And maybe the BW varies at different power levels also?
I could be wrong...

Pete
Re: HP 1727A CRO: Problem with the vertical output amplifier.

 

pins 7 and 5 same as U1 pins 12 and 13.

U2 pin 6: 20V
U2 pins 2 and 3: 42V?

Should pin 6 be that high? obviously it is outputting current to the 15V rail, about 155mA, but I don't know.?
Re: massive attachments

 

On Wed, 23 Feb 2022 at 17:34, Roy J. Tellason, Sr. <roy@...> wrote:
This is a mailing list,? not some web thingy.? At least that's the way *I* access it,? my mail program hits the servers and downloads this stuff...

But it is a "web thingy" - it is not just a mailing list.? How you choose it is up to you, but as has been pointed out, you can restrict the size of attachments, including setting the size to 0, so you never see any.


While DSL was at one time considered "broadband",? it's a poor performer compared to what some folks do with cable,? etc.? Unfortunately this rural location doesn't provide a whole lot of choices.
I am in the same boat - ADSL from a rural location in the UK.?

The point here is that when one of you guys attaches a multi-megabyte file to one of these emails,? I get to download it whether I want it or not.? Which ties up my connectivity until the download is done.
?
It does not need to.?

I don't mind the occasional pictures and such,? but those big files are something else!
I can't be bothered to check, but I think you can get images downloaded, but at a resolution you set. So you see the image. If you want higher quality, go to the web server.?

I'd appreciate it if you guys could simply put such large files where somebody can get at them,? and provide a link,? for those that want it,? rather than forcing those of us who get things this way to download for no immediate benefit.

Dave (group owner)
Re: massive attachments

 

Hi Kuba

I think you misunderstood what I was saying put the picture in the pictures file and then put a link to the pictures file
This should stop multiple copies appearing on the site also
Then they can be deleted later by the person that put them there

Regards Paul

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Kuba Ober via groups.io
Sent: 24 February 2022 00:21
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] massive attachments

Groups.io already converts attachments to links. You just have to reject all attachments in your settings on groups.io.

Cheers, Kuba

23 feb. 2022 kl. 6:23 em skrev Paul Bicknell <admin@...>:

?Hi all
I believe in your personal settings you can set an attachment limit to
the size of attachment that you reweave Personally I would prefer all
attachments to stop and pictures put into a file with a link to them
from the posting

This would also stop multiple attachments each time a mail is replied
to that has an attachment Also in most cases 1 meg is big enough to
display the problem

Regards Paul

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Bruce
Sent: 23 February 2022 23:04
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] massive attachments

Can you configure your e-mail application to leave attachments on the server and only down load them if requested. Most clients have tis setting.

Cheers!

Bruce

Quoting Dave Daniel <kc0wjn@...>:

This is exactly the reason why many groups do not allow attachments.

DaveD

On Feb 23, 2022, at 14:02, Larry McElhiney via groups.io
<lmcelhiney@...> wrote:

?On Wed, Feb 23, 2022 at 12:33 PM, Roy J. Tellason, Sr. wrote:
I'd appreciate it if you guys could simply put such large files
where somebody can get at them, and provide a link, for those that
want it, rather than forcing those of us who get things this way to
download for no immediate benefit.
Hi Roy,

In your subscription to this group, go to Advanced and you will see
the maximum attachment size option, below:


…
Max Attachment Size


Maximum size of attachments sent to you in emails. For attachments
larger than this size, links to retrieve them will be provided
instead.
…

You can control the attachments which are sent to you.

Also, you can change Digest or Summary rather than All Messages,
which allows you to choose individual messages.



Take care,

Larry
Re: massive attachments

 

On Wed, 23 Feb 2022 at 23:22, Paul Bicknell <admin@...> wrote:
Hi all
I believe in your personal settings you can set an attachment limit to the size of attachment that you reweave
?
Yes, one can set any limit on attachments, even including a size of zero so you don't get any. i believe that will compress images to a size you set too, although I am unsure of that.?

Personally I would prefer all attachments to stop and pictures put into a file with a link to them from the posting
?
But most people could not be bothered with that hassle. It is far easier to attach something.?

This would also stop multiple attachments each time a mail is replied to that has an attachment
?
Yes, that is annoying, but still better than expecting people to? upload to a file area.

?
Also in most cases 1 meg is big enough to display the problem
Agreed.?

Regards Paul
?
Dave (group owner)
Re: massive attachments

 

Groups.io already converts attachments to links. You just have to reject all attachments in your settings on groups.io.

Cheers, Kuba

23 feb. 2022 kl. 6:23 em skrev Paul Bicknell <admin@...>:

?Hi all
I believe in your personal settings you can set an attachment limit to the size of attachment that you reweave
Personally I would prefer all attachments to stop and pictures put into a file with a link to them from the posting

This would also stop multiple attachments each time a mail is replied to that has an attachment
Also in most cases 1 meg is big enough to display the problem

Regards Paul

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Bruce
Sent: 23 February 2022 23:04
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] massive attachments

Can you configure your e-mail application to leave attachments on the server and only down load them if requested. Most clients have tis setting.

Cheers!

Bruce

Quoting Dave Daniel <kc0wjn@...>:

This is exactly the reason why many groups do not allow attachments.

DaveD

On Feb 23, 2022, at 14:02, Larry McElhiney via groups.io
<lmcelhiney@...> wrote:

?On Wed, Feb 23, 2022 at 12:33 PM, Roy J. Tellason, Sr. wrote:
I'd appreciate it if you guys could simply put such large files where
somebody can get at them, and provide a link, for those that want it,
rather than forcing those of us who get things this way to download
for no immediate benefit.
Hi Roy,

In your subscription to this group, go to Advanced and you will see
the maximum attachment size option, below:


…
Max Attachment Size


Maximum size of attachments sent to you in emails. For attachments
larger than this size, links to retrieve them will be provided
instead.
…

You can control the attachments which are sent to you.

Also, you can change Digest or Summary rather than All Messages,
which allows you to choose individual messages.



Take care,

Larry
Re: HP 8594E upgrade CRT to LCD

 

There is a lot of room left over after removing the old monitor. It could be a good place to install a Rubidium frequency reference with room left over. There is also a port not used on the front for the output.? Too bad my Rubidium is in another case already.?

Dwight
Re: massive attachments

 

Hi all
I believe in your personal settings you can set an attachment limit to the size of attachment that you reweave
Personally I would prefer all attachments to stop and pictures put into a file with a link to them from the posting

This would also stop multiple attachments each time a mail is replied to that has an attachment
Also in most cases 1 meg is big enough to display the problem

Regards Paul

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Bruce
Sent: 23 February 2022 23:04
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] massive attachments

Can you configure your e-mail application to leave attachments on the server and only down load them if requested. Most clients have tis setting.

Cheers!

Bruce

Quoting Dave Daniel <kc0wjn@...>:

This is exactly the reason why many groups do not allow attachments.

DaveD

On Feb 23, 2022, at 14:02, Larry McElhiney via groups.io
<lmcelhiney@...> wrote:

?On Wed, Feb 23, 2022 at 12:33 PM, Roy J. Tellason, Sr. wrote:
I'd appreciate it if you guys could simply put such large files where
somebody can get at them, and provide a link, for those that want it,
rather than forcing those of us who get things this way to download
for no immediate benefit.
Hi Roy,

In your subscription to this group, go to Advanced and you will see
the maximum attachment size option, below:


…
Max Attachment Size


Maximum size of attachments sent to you in emails. For attachments
larger than this size, links to retrieve them will be provided
instead.
…

You can control the attachments which are sent to you.

Also, you can change Digest or Summary rather than All Messages,
which allows you to choose individual messages.



Take care,

Larry
Re: massive attachments

 

Can you configure your e-mail application to leave attachments on the server and only down load them if requested. Most clients have tis setting.

Cheers!

Bruce

Quoting Dave Daniel <kc0wjn@...>:

This is exactly the reason why many groups do not allow attachments.

DaveD

On Feb 23, 2022, at 14:02, Larry McElhiney via groups.io <lmcelhiney@...> wrote:

?On Wed, Feb 23, 2022 at 12:33 PM, Roy J. Tellason, Sr. wrote:
I'd appreciate it if you guys could simply put such large files where somebody can get at them, and provide a link, for those that want it, rather than forcing those of us who get things this way to download for no immediate benefit.
Hi Roy,

In your subscription to this group, go to Advanced and you will see the maximum attachment size option, below:


…
Max Attachment Size


Maximum size of attachments sent to you in emails. For attachments larger than this size, links to retrieve them will be provided instead.
…

You can control the attachments which are sent to you.

Also, you can change Digest or Summary rather than All Messages, which allows you to choose individual messages.



Take care,

Larry
Re: massive attachments

 

On 2022-02-23, at 23:55, Dave Daniel <kc0wjn@...> wrote:

This is exactly the reason why
The fact that this entire issue is already neatly solved in groups.io?
No, that is a reason to let the attachments flow.
(Reasonable restraint is good, administratively prohibiting is bad.)

many groups do not allow attachments.
Let’s not be *that* uncle.

Grü?e, Carsten
Re: massive attachments

 

开云体育

This is exactly the reason why many groups do not allow attachments.

DaveD

On Feb 23, 2022, at 14:02, Larry McElhiney via groups.io <lmcelhiney@...> wrote:

?On Wed, Feb 23, 2022 at 12:33 PM, Roy J. Tellason, Sr. wrote:
I'd appreciate it if you guys could simply put such large files where somebody can get at them, and provide a link, for those that want it, rather than forcing those of us who get things this way to download for no immediate benefit.

Hi Roy,

In your subscription to this group, go to Advanced and you will see the maximum attachment size option, below:

…
Max Attachment Size

?? ?? ?? ?? ? Unlimited ?? ?? ?? ?? ? 0 (no attachments) ?? ?? ?? ?? ? 100KB ?? ?? ?? ?? ? 500KB ?? ?? ?? ?? ? 5MB ? ? ?? ?? ?

Maximum size of attachments sent to you in emails. For attachments larger than this size, links to retrieve them will be provided instead.
…

You can control the attachments which are sent to you.

Also, you can change Digest or Summary rather than All Messages, which allows you to choose individual messages.


Take care,

Larry
How can I measure the bandwidth of an audio transformer with the HP8903B ?

 

Good day everyone,
 I would like to measure the bandwidth of an audio output transformer for a push-pull tube amplifier, using the HP8903B audio analyzer, but I have some doubts about how to connect the transformer to the input and output of the HP8903B.
 The primary of the transformer (anode - anode):? do I connect them to the HP8903B output (set to 50 ohm or 600 ohm)?
 Do I connect an 8 ohm resistor and the input of the HP8903B to the 8 ohm secondary of the transformer?
What voltage should I set for the HP8903B output?

 Thanks for the attention
--.Cheers
??? Attilio
? ?
Re: HP 8594E upgrade CRT to LCD

 

开云体育

Yes, and no.

The EL panel is quite thin and should be relatively easy to physically replace on some of the displays I've seen.? Now you have to find the replacement.

It's possible that the plastic diffuser panel from an LED backlit display might fit, but that may be a difficult thing to do, both to find the panel and to replace it.

You may be able to find a replacement by googling for EL replacement for that display.

I had a tektronix TM5000 function generator with a bad EL panel, and ended up finding an equivalent LED backlit panel.? I actually think that the reverse background looks better.

It might be possible to find a later LCD display with the same mechanical size that uses LEDS or a CCFL.? Bear in mind that the inverter for the CCFL is 900 to 1.5 KV, and the EL is 100 or so.? Be very careful with the CCFL inverter.? I'd personally avoid them and their displays wherever possible.? It is possible to replace a CCFL lamp with an LED array, though.? Some of the replacements are commercially made.

Harvey


On 2/23/2022 4:28 PM, Dave Brown wrote:

Is it possible to give the EL display backlights any new lease of life?? HP used them in a number of instruments and most ‘fixes’ I’ve seen so far mean a replacement.

DaveB, ?NZ

?

From: [email protected] [mailto:[email protected]] On Bethalf Of Harvey White
Sent: Thursday, February 24, 2022 09:46
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 8594E upgrade CRT to LCD

?

From what I've seen, the displays are from a different era, and that could make a significant difference.? Modern TFT displays seem to be a lot more durable.

On the old displays, the EL backlight gives out quickly.

Also not sure about the temperature tolerance, either, although LCD displays do not really like getting too hot.

Harvey

On 2/23/2022 3:09 PM, paulswed wrote:

Stuart not to throw stones. But I have seen a fair number of tek lcd displays that have gone to heck. Normally something like crystal leakage. (I just made that up). I can think of things like the tek TDR 1503 non crt versions yet the crt versions still work.

Just saying we hobbiest users use the gear far past any expectation that it should work.

Regards

Paul

WB8TSL
Re: HP 8594E upgrade CRT to LCD

 

开云体育

Is it possible to give the EL display backlights any new lease of life?? HP used them in a number of instruments and most ‘fixes’ I’ve seen so far mean a replacement.

DaveB, ?NZ

?

From: [email protected] [mailto:[email protected]] On Behalf Of Harvey White
Sent: Thursday, February 24, 2022 09:46
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 8594E upgrade CRT to LCD

?

From what I've seen, the displays are from a different era, and that could make a significant difference.? Modern TFT displays seem to be a lot more durable.

On the old displays, the EL backlight gives out quickly.

Also not sure about the temperature tolerance, either, although LCD displays do not really like getting too hot.

Harvey

On 2/23/2022 3:09 PM, paulswed wrote:

Stuart not to throw stones. But I have seen a fair number of tek lcd displays that have gone to heck. Normally something like crystal leakage. (I just made that up). I can think of things like the tek TDR 1503 non crt versions yet the crt versions still work.

Just saying we hobbiest users use the gear far past any expectation that it should work.

Regards

Paul

WB8TSL
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