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Re: Solder Flux

 

It's useful for cleaning badly oxidized soldering iron tips, but don't use it on circuit bits, as Michael T. warned. It will digest your wiring over time.

Cheers,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070

On 10/17/2024 1:56 AM, Brad Latta wrote:
I have some old solder Flux here that I use for cleaning up oxidized & dirty connections when I replaced components in vintage HP equipment, this Flux has 27% Zinc Chloride, which really helps to wet the connection for soldering. I am wondering how bad is the Zinc Chloride, and what precautions should I take when using it?, maybe someone here has used a similar Flux before,
Re: Solder Flux

 

That is highly corrosive flux intended for plumbing, not electronics. Don't use it on anything electronic, .

On Thu, Oct 17, 2024 at 4:57?AM Brad Latta via <bradley.latta=gmail.com@groups.io> wrote:
I have some old solder Flux here that I use for cleaning up oxidized & dirty connections when I replaced components in vintage HP equipment, this Flux has 27% Zinc Chloride, which really helps to wet the connection for soldering. I am wondering how bad is the Zinc Chloride, and what precautions should I take when using it?, maybe someone here has used a similar Flux before,?
? ? ? ? ? ? ? ? ?Brad
Re: HP 3585A CRT Twitch

 

This looks very much like the effect of power supply noise. Try probing the supply lines with an AC-coupled scope.
And please let us know !
Joel
Solder Flux

 

I have some old solder Flux here that I use for cleaning up oxidized & dirty connections when I replaced components in vintage HP equipment, this Flux has 27% Zinc Chloride, which really helps to wet the connection for soldering. I am wondering how bad is the Zinc Chloride, and what precautions should I take when using it?, maybe someone here has used a similar Flux before,?
? ? ? ? ? ? ? ? ?Brad
Re: HP 182T Power Supply Troubleshooting

 

开云体育

Thank you Frank?

For the link and explanation I think ?a? short explanation and a link to get the Software in the new file might help and encourage members to start using LTSpice

?

Regards Paul

?

From: HP-Agilent-Keysight-equipment@groups.io [mailto:HP-Agilent-Keysight-equipment@groups.io] On Behalf Of Frank Mashockie
Sent: 17 October 2024 03:01
To: HP-Agilent-Keysight-equipment@groups.io
Subject: Re: [HP-Agilent-Keysight-equipment] HP 182T Power Supply Troubleshooting

?

Paul,

?

It is free to download from Analog Device's website here!

?

It is a circuit simulator software.? So you can build your own circuit in there and run it as a simulation.? You can check all kinds of parameters.? I still haven't realized all its functions, but so far it seems pretty easy to use!

?

My initial thought was by creating a 'LTSpice File' folder in the 'Files' section, is that I see people share snapshots from LTSpice on here alot to help people with troubleshooting.? If they've already built the circuit in LTSpice, then maybe they could share the whole file.? ?That way the person who is trying to troubleshoot could experiment with it themselves; they wouldn't have to ask someone else for specifics.? But I didn't realize there was already a directory for all the equipment.? It makes more sense to share it there.

?

-Frank
Re: HP 346A Noise Source Below 10 MHz #file-notice

 

I think at these low frequencies, a digital source would be much better? A linear feedback shift register with 100MHz clock with a lot of post attenuation would give a perfect spectrum at 10 MHz. A simple CPLD could be programmed, or maybe even 74AC logic would do. You can make the register arbitrarily long, to avoid periodicity.
Re: HP 182T Power Supply Troubleshooting

 

Paul,
?
It is free to download from Analog Device's website here!
?
It is a circuit simulator software.? So you can build your own circuit in there and run it as a simulation.? You can check all kinds of parameters.? I still haven't realized all its functions, but so far it seems pretty easy to use!
?
My initial thought was by creating a 'LTSpice File' folder in the 'Files' section, is that I see people share snapshots from LTSpice on here alot to help people with troubleshooting.? If they've already built the circuit in LTSpice, then maybe they could share the whole file.? ?That way the person who is trying to troubleshoot could experiment with it themselves; they wouldn't have to ask someone else for specifics.? But I didn't realize there was already a directory for all the equipment.? It makes more sense to share it there.
?
-Frank
Re: HP 182T Power Supply Troubleshooting

 

开云体育

Hi frank

All ok but how does one get the ?LTSpice? program? ?

Do we have to pay for it ?

?

I have spent? a lot of time with the 180 series of scopes in my younger days as lots of different units can plug into the 180 series

And still use them as my main scope on the bench why did you have to create a 100 Volt rail for the scope

I can’t quiet remember the CCT for the 100 v rail on the 182 but I assume it is much the same as a 180

?

Regards Paul

?

From: HP-Agilent-Keysight-equipment@groups.io [mailto:HP-Agilent-Keysight-equipment@groups.io] On Behalf Of Frank Mashockie
Sent: 17 October 2024 01:52
To: HP-Agilent-Keysight-equipment@groups.io
Subject: Re: [HP-Agilent-Keysight-equipment] HP 182T Power Supply Troubleshooting

?

Hi Paul,

?

Sorry for the numerous mistakes here.? 1) I fixed the spelling mistake in the file name.? 2) I did not realize there was a whole directory for all the HP equipment with their own folders cataloged within this group.? That is awesome.? I can add the file there.

?

So this is an LTSpice file.? I created the 100V rail for the HP 182T low voltage power supply.? I was under the impression that anyone with LTSpice could open this file from home if they have the software to use for troubleshooting.? But maybe I was mistaken.? I did this for two reasons: 1) I wanted to get acquainted with the software using a previous circuit I worked on.? 2) Since I already created the file, I figured I would share it with everyone here for future troubleshooting purposes.

?

-Frank

?

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Re: HP 182T Power Supply Troubleshooting

 

Hi Paul,
?
Sorry for the numerous mistakes here.? 1) I fixed the spelling mistake in the file name.? 2) I did not realize there was a whole directory for all the HP equipment with their own folders cataloged within this group.? That is awesome.? I can add the file there.
?
So this is an LTSpice file.? I created the 100V rail for the HP 182T low voltage power supply.? I was under the impression that anyone with LTSpice could open this file from home if they have the software to use for troubleshooting.? But maybe I was mistaken.? I did this for two reasons: 1) I wanted to get acquainted with the software using a previous circuit I worked on.? 2) Since I already created the file, I figured I would share it with everyone here for future troubleshooting purposes.
?
-Frank
?
?
Re: HP 346A Noise Source Below 10 MHz #file-notice

 

Don't pay too much attention to the 0.43dB value seen on the delta marker in the plots as this jumps around quite a bit even with lots of averaging.? However, there's about a 3.5dB difference (Y factor) between hot and cold so the ENR is going to be in the ballpark of 0.7dB lower at 2MHz?
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On my old notes I only saw about 0.2dB noise droop at 2MHz but I probably didn't take that much time or care over this. I may have used a different INGaP MMIC as well. I'll try and sort out the preamp over the weekend. The VSWR and frequency response is already quite good but I can make it even better.
Re: HP 346A Noise Source Below 10 MHz #file-notice

 

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I dug out and tried the original external preamp on the RTSA (Tek RSA3408A) and then fitted the 346A at the input. I then flipped between hot and cold states. See the screenshots below. You can see there is a flat response from 10MHz down to maybe 3MHz and then there is some obvious loss in noise level below 2MHz. This is essentially the same test I did a few years ago.
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This is about the same as I saw when I did this last time. I probably also (further) tweaked the ENR table in the noise figure analyser menu after I did all this. I can't remember now as I did it quite a few years ago when I first got the noise source and the associated analyser that can measure noise figure. I think this was back in late 2019.
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The first plot shows the cold state and the noise floor is really flat. The noise floor is just as flat for just the raw analyser (without the preamp) but obviously at a much lower level. The typical noise floor is about 20dB lower without the preamp.
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The second plot shows what happens when I turn on the HP 346A. It looks like the droop in noise level starts below about 3MHz and this gets worse by 1MHz.
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I just spotted that I should have calibrated the analyser just before running these plots as it's possible to reduce the dc spike with a calibration. However, this doesn't really affect the results.
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If anyone is interested, I can share the design of the BJT stage although it might be better to wait until I tweak it for (very) low port VSWR.
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The MMIC stage is just a Minicircuits eval board but I need to change the biasing choke and optimise the biasing for best performance.
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It may be the case that the result will change once I tweak the preamp for lower VSWR and a flatter response but I doubt it will change a lot.
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The input VSWR of the analyser is impressively low even when set to its most sensitive range because it is set to act as a baseband analyser in the plots below. So it is a bit like a 40MHz soundcard with a 50R input.
?
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Re: HP 346A Noise Source Below 10 MHz #file-notice

 

I'm probably going to do it the same way as last time using an old Tek RTSA as the noise measuring receiver.? This analyser has a low noise floor and a very flat response and a very flat noise floor right down to audio frequencies. The technique last time was to use a BJT based wideband 50R amplifier to drive an InGaP MMIC to act as a preamp.?
The assumption is that the noise figure of the BJT stage (BFR91 based) should be consistent from about 40MHz down to maybe 2MHz or even lower. So hopefully, the preamp will not contribute any slope to the noise response seen on the analyser at lower frequencies.
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The RTSA frequency response and noise floor is very flat when used below 40MHz because it acts as a baseband analyser below 40MHz. However, I am going to try and improve the BJT stage to improve the input and output return loss. I can also tweak the InGaP MMIC board to improve the frequency response below 10MHz to make it ultra flat. It's going to be quite difficulat to manage all the contributors to uncertainty, but this is realistically the only way I can do this here at home.
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If the ENR of the noise source was totally flat then the noise level seen on the analyser should rise but still be flat once the noise source was set to the hot state. The last time I did this I saw a slight droop down in noise level between 5MHz and 2MHz. Hopefully, I can modify the BJT amp and the MMIC to minimise mismatch uncertainty and also improve the frequency response. This should provide a more reliable result.? I probably won't be able to do all this until the weekend though.
?
It's important to use a preamp with low 1/f noise and so I used the BJT stage for the first stage of the preamp.?
Re: HP 182T Power Supply Troubleshooting

 

Hi could you please explain HT 182 LV 100V rail.asc as i cannot open the file?
also if it is for the 182? should it be in the 182 file?
regards Paul??
Re: HP 182T Power Supply Troubleshooting

 

Thanks Ozan!? I still have a lot to learn about how to use the program to is fullest, but I thought this was a good start!
?
?
-Frank
HP 3585A CRT Twitch

 

Afternoon all!
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I've had this HP 3585A for a few weeks now and it's been working great. Tonight I noticed that the CRT is, for lack of a better term, twitching. I took a video and you can see it more clearly once I turn down the CRT intensity later in the video. Also note the reference line is not as pure as it once was. It's almost striped looking now.?
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Any idea what could be causing this? I would assume a power supply issue.
Re: HP 346A Noise Source Below 10 MHz #file-notice

 

Thanks. Looking at your other plot, I think your spectrum analyser plot is a plot of noise output vs frequency. It looks like your noise source has a steeper noise reduction than mine as the frequency is reduced. It may be that your noise source has a different capacitance value for the dc blocking cap inside it?
?
I can try and come up with a better way of measuring mine to try and characterise it better. I didn't spend much time on this last time. I don't think it will reduce by 2dB by 2MHz and by 4dB at 1MHz though.?
?
I've also got a couple of homebrew noise sources here. One contains a decent Noisecom noise diode and the other uses a high frequency diode. I think it's a Schottky diode but I can't remember now. It works very well up to several GHz. The Noisecom source is only really good to about 1300MHz although it is supposed to work down to 200kHz according to the datasheet.
Re: HP 182T Power Supply Troubleshooting

 

Typo in R11B formula in the previous message, correct formula is below. It was missing a parenthesis although LTspice didn't mind it.
Ozan
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.param R11setting=0.5

R11A N014 N012 {1000*R11setting}

R11B N012 N017 {1000*(1-R11setting)}

?
?
On Wed, Oct 16, 2024 at 11:03 AM, Ozan wrote:

I usually parameterize trimpots like the example below. Then you can use e.g. (0,1) range to try 0%-100% trimpot settings or change the formula to R11setting/100.0 if you like (0,100) range better. LTspice doesn't like 0-ohm resistors, R11setting of exactly 0.0 and 1.0 won't work in the example below. ?
Ozan
?

.param R11setting=0.5

R11A N014 N012 {1000*R11setting}

R11B N012 N017 {1000*(1-R11setting}

?

?
?
On Wed, Oct 16, 2024 at 06:48 AM, Frank Mashockie wrote:
I'm looking to go back to school to get a degree in EE and I'm previewing some courses.? Needed to familarize myself with LTSpice.? So I created the 100V from the 182T just to mess around.? Of course I also put a few of the transistors in backwards just like I did in reality a few weeks ago! lol.? But after fixing that, it works!? Unfortunately I don't think you can add trimpots, so you have to adjust the value of R12 to adjust the voltage.? Right now it is dialed in at 100.3V.? I created a folder called 'LTSpice' so people can add files for any simulation related to HP equipment.? I added this file to that folder.? I figured it could come in handy for troubleshooting purposes.
Re: HP 182T Power Supply Troubleshooting

 

I usually parameterize trimpots like the example below. Then you can use e.g. (0,1) range to try 0%-100% trimpot settings or change the formula to R11setting/100.0 if you like (0,100) range better. LTspice doesn't like 0-ohm resistors, R11setting of exactly 0.0 and 1.0 won't work in the example below. ?
Ozan
?

.param R11setting=0.5

R11A N014 N012 {1000*R11setting}

R11B N012 N017 {1000*(1-R11setting}

?

?
?
On Wed, Oct 16, 2024 at 06:48 AM, Frank Mashockie wrote:

I'm looking to go back to school to get a degree in EE and I'm previewing some courses.? Needed to familarize myself with LTSpice.? So I created the 100V from the 182T just to mess around.? Of course I also put a few of the transistors in backwards just like I did in reality a few weeks ago! lol.? But after fixing that, it works!? Unfortunately I don't think you can add trimpots, so you have to adjust the value of R12 to adjust the voltage.? Right now it is dialed in at 100.3V.? I created a folder called 'LTSpice' so people can add files for any simulation related to HP equipment.? I added this file to that folder.? I figured it could come in handy for troubleshooting purposes.
Re: HP 346A Noise Source Below 10 MHz #file-notice

 

You are correct, JMR. The 346A is a lot better below 10 MHz than the 346B.
?
Vladan
Re: HP 346A Noise Source Below 10 MHz #file-notice

 

Just to clarify, the thread title does ask about the HP 346A and so I gave estimated VSWR data for the HP 346A. The 346A has much lower VSWR than the 346B. You can typically expect to see less than 1.02:1 VSWR at 10MHz with the 346A and this will degrade to about 1.05:1 by about 300kHz. It might degrade to 1.06:1 by 100kHz.
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I did also say I couldn't remember how much worse the 346B VSWR was. I would guess that the 346B has maybe 9dB less attenuation after the diode because it has a higher ENR at its output. So the VSWR will obviously be worse than the 346A in this respect.
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