Author Topic: HP/Keysight 66311B magnetic field leakage  (Read 4982 times)

0 Members and 1 Guest are viewing this topic.

Offline electronomicon

  • Contributor
  • Posts: 34
  • Country: de
Re: HP/Keysight 66311B magnetic field leakage
« Reply #25 on: December 02, 2023, 01:27:10 pm »
Does the 34401A not also have a 240V line voltage setting? Or was that not enough to fix the issue? Glad the suggestion helped with the other unit.
It does, but other than my 33120A it was already set to 240 V. So for both devices, setting them to 240 V line voltage helped but didn’t fully resolve the issue.
 

Offline GulftownTopic starter

  • Contributor
  • Posts: 42
  • Country: de
Re: HP/Keysight 66311B magnetic field leakage
« Reply #26 on: December 02, 2023, 05:07:19 pm »
Okay I found a solution I think.
I will use a 230V/24V transformer and use it as an bucking transformer to reduce the input voltage on the primary of the original transformer.
That should work without introducing side effects.
I will keep you updated.
Bucking transformer is indeed the right way to go if you need to drop mains voltage a little. If you do it in the configuration shown in Fig. 4 here then you also avoid saturation issues on the bucking transformer: https://sound-au.com/articles/buck-xfmr.htm

I would test by dropping the voltage a bit with a variac first though to be sure it's actually going to solve the issue before spending the time and money wiring up the bucking transformer.

Thanks for the suggestion, i already hacked together a classic bucking transformer using tranformer from an old ac/ac wall plug, but i think that i dont have any saturation effects in the bucking transformer itself.

The output of the bucking transformer is now 206V RMS.
When i bould a proper 3d printed housing for the transformer i will change the circuit to the one you suggested.

The effect on the TDS 460A is now barely noticable and ob my Tek 2230 the screen is completely stable.
I will add some mu-metal anyway, because i already ordered it.
But i think the bucking transformer is the best solution.
 

Offline electronomicon

  • Contributor
  • Posts: 34
  • Country: de
Re: HP/Keysight 66311B magnetic field leakage
« Reply #27 on: December 02, 2023, 05:19:32 pm »
Can someone give me a hint where to get something like that ready to use? Or what to look for?

I read through the link @Hydron provided and I’m definitely not knowledgeable enough about AC stuff to start fiddling around with something here myself (like, if someone would point me to a transformer that’s safe to use and does the job, I could safely put it to use, but I don’t know enough to find the right transformer myself).

I tried to search the web, but didn’t really find anything useful.
 

Offline coppercone2

  • Super Contributor
  • ***
  • Posts: 11336
  • Country: us
  • $
Re: HP/Keysight 66311B magnetic field leakage
« Reply #28 on: December 02, 2023, 05:39:19 pm »
a good UPS might do it too if you want a integrated solution. they have taps to reduce voltage.
 

Offline GulftownTopic starter

  • Contributor
  • Posts: 42
  • Country: de
Re: HP/Keysight 66311B magnetic field leakage
« Reply #29 on: December 02, 2023, 05:44:04 pm »
Can someone give me a hint where to get something like that ready to use? Or what to look for?

I read through the link @Hydron provided and I’m definitely not knowledgeable enough about AC stuff to start fiddling around with something here myself (like, if someone would point me to a transformer that’s safe to use and does the job, I could safely put it to use, but I don’t know enough to find the right transformer myself).

I tried to search the web, but didn’t really find anything useful.

A Variac is a proper solution, while a litte bit more expensive, it is the safest and easiest option i think.

Europe:
https://www.ebay.de/itm/134252519871?mkevt=1&mkcid=1&mkrid=707-53477-19255-0&campid=5338748320&toolid=20006&customid=atk-lfgaAAAAjAnwk3FSYi32B_0cAAAAAA
USA:
https://www.ebay.com/itm/221484094745?hash=item33917b1519:g:EZMAAOSwj0NUf1NI&amdata=enc%3AAQAIAAAA0AN6wNHZ%2BLD7yqCDPrjrkp8k3lqkc0pzIdCSD%2BtzRFX0lyGcvZTtj1EP1ADM5W5kZGdRa4swMHiLJYEG9VQa0YOFOCsGmYVeg83m0BOBcJagI5NOzvZqMwyhj5zvjko0SeHAMkOou%2FobqQTw2b9E9fVD9ME4QFzpVBtPmJlvIJi3T5omVE4xMUySBzdj74k33ALKdUJBtxHwWKXWWcYdhlMoXJakurblLUMcZash4xiV0Xtbtd6RNV5sV2E%2FoQOstbajjqQ78BRwxjIUTHuPM28%3D%7Ctkp%3ABFBMxOuBuoVj

this is essentialy a variable version of my hacked bucking transformer.
 

Offline electronomicon

  • Contributor
  • Posts: 34
  • Country: de
Re: HP/Keysight 66311B magnetic field leakage
« Reply #30 on: December 02, 2023, 06:17:52 pm »
Thanks for the suggestions!
Ideally, I’d like something that I can fit into my cupboard together with the devices, because this is all in my living space and I don’t really have room for a large separate solution. This restricts the size to maximum about the same as the devices.

But if that doesn’t exist and/or is too complicated to set up myself, I’m also fine with the current state of the noise problem.
 

Offline AVGresponding

  • Super Contributor
  • ***
  • Posts: 4931
  • Country: england
  • Exploring Rabbit Holes Since The 1970s
Re: HP/Keysight 66311B magnetic field leakage
« Reply #31 on: December 02, 2023, 08:51:23 pm »
Thanks for the suggestions!
Ideally, I’d like something that I can fit into my cupboard together with the devices, because this is all in my living space and I don’t really have room for a large separate solution. This restricts the size to maximum about the same as the devices.

But if that doesn’t exist and/or is too complicated to set up myself, I’m also fine with the current state of the noise problem.

Have a watch of this: https://odysee.com/@bigclivedotcom:0d/adjust-your-mains-voltage-with-a:8
nuqDaq yuch Dapol?
Addiction count: Agilent-AVO-BlackStar-Brymen-Chauvin Arnoux-Fluke-GenRad-Hameg-HP-Keithley-IsoTech-Mastech-Megger-Metrix-Micronta-Racal-RFL-Siglent-Solartron-Tektronix-Thurlby-Time Electronics-TTi-UniT
 
The following users thanked this post: electronomicon

Offline electronomicon

  • Contributor
  • Posts: 34
  • Country: de
Re: HP/Keysight 66311B magnetic field leakage
« Reply #32 on: December 03, 2023, 03:15:06 pm »
Have a watch of this: https://odysee.com/@bigclivedotcom:0d/adjust-your-mains-voltage-with-a:8

Thanks, this was really helpful!

To apply this to my use case:
- I have two devices, fused to 250 mA and 500 mA on the line input.
- I measured my line voltage to about 235 Vrms.

So I should look for a transformer rated for 230 V on the primary, 15 V on the secondary and at least 11,25 VA. Or is there any reason I should not hook up both devices to the same transformer?

Edit:
This then seems to be a viable option?

I also looked specifically for halogen transformers like the one used in the video. But I find a lot of them are labelled as “electronic transformers”. What does that mean? Will these work or are these electronic replacement circuits for a traditional transformer and will behave differently for this specific use case?
« Last Edit: December 03, 2023, 03:21:00 pm by electronomicon »
 

Offline GulftownTopic starter

  • Contributor
  • Posts: 42
  • Country: de
Re: HP/Keysight 66311B magnetic field leakage
« Reply #33 on: December 03, 2023, 04:29:32 pm »
Have a watch of this: https://odysee.com/@bigclivedotcom:0d/adjust-your-mains-voltage-with-a:8

Thanks, this was really helpful!

To apply this to my use case:
- I have two devices, fused to 250 mA and 500 mA on the line input.
- I measured my line voltage to about 235 Vrms.

So I should look for a transformer rated for 230 V on the primary, 15 V on the secondary and at least 11,25 VA. Or is there any reason I should not hook up both devices to the same transformer?

Edit:
This then seems to be a viable option?

I also looked specifically for halogen transformers like the one used in the video. But I find a lot of them are labelled as “electronic transformers”. What does that mean? Will these work or are these electronic replacement circuits for a traditional transformer and will behave differently for this specific use case?

If the transformer is rated for atleast 11.25VA i dont see a problem hooking up two devices.

It must be a real transformer, Switching (electronic) power supplys would not work.
The NT 12VA 2X15 should work perfectly, you can use both secondary in parallel if you want.
 
The following users thanked this post: electronomicon

Offline Hydron

  • Super Contributor
  • ***
  • Posts: 1085
  • Country: gb
Re: HP/Keysight 66311B magnetic field leakage
« Reply #34 on: December 04, 2023, 12:41:53 am »
It's worth noting that the bucking transformer is only useful if the field leakage is made worse by a transformer starting to saturate. Don't assume that it's a guaranteed fix unless you've tested with reduced voltage first (hence my Variac suggestion - it's not a permanent solution but a very good way to test before mucking about with other transformers).
 

Offline Jay_Diddy_B

  • Super Contributor
  • ***
  • Posts: 2766
  • Country: ca
Re: HP/Keysight 66311B magnetic field leakage
« Reply #35 on: December 04, 2023, 05:13:13 am »
Hi,

If you have a current probe capture the current waveform with the secondary winding open. This is probably a 50/60Hz thing.

A 50Hz transformer requires more turns than a 60Hz transformer for the same magnetic flux density.

The transformer was probably designed in a 60Hz country.

Jay_Diddy_B
 

Offline electronomicon

  • Contributor
  • Posts: 34
  • Country: de
Re: HP/Keysight 66311B magnetic field leakage
« Reply #36 on: December 05, 2023, 05:48:00 pm »
It's worth noting that the bucking transformer is only useful if the field leakage is made worse by a transformer starting to saturate. Don't assume that it's a guaranteed fix unless you've tested with reduced voltage first (hence my Variac suggestion - it's not a permanent solution but a very good way to test before mucking about with other transformers).

As I don’t have a Variac, I decided to go for a regular transformer and test it out that way.
The result is quite interesting. It’s hard to tell if it makes a difference for only one of the devices turned on. But if I turn both of them on, this now actually reduces the wobble instead of increasing, as it did before. With both running, it’s basically gone now. So I guess I will keep the transformer and put it into a more permanent form.
Any ideas why running both devices might reduce the wobble compared to just one?

If you have a current probe capture the current waveform with the secondary winding open. This is probably a 50/60Hz thing.

A 50Hz transformer requires more turns than a 60Hz transformer for the same magnetic flux density.

The transformer was probably designed in a 60Hz country.

Unfortunately, I don’t have one. But from my reading (of the previously linked article and some more afterwards) I understood that in this case reducing the voltage should still help. Is that correct?
 

Offline AVGresponding

  • Super Contributor
  • ***
  • Posts: 4931
  • Country: england
  • Exploring Rabbit Holes Since The 1970s
Re: HP/Keysight 66311B magnetic field leakage
« Reply #37 on: December 06, 2023, 06:13:03 am »
Presumably some additional voltage drop due to current loading?   :-//
nuqDaq yuch Dapol?
Addiction count: Agilent-AVO-BlackStar-Brymen-Chauvin Arnoux-Fluke-GenRad-Hameg-HP-Keithley-IsoTech-Mastech-Megger-Metrix-Micronta-Racal-RFL-Siglent-Solartron-Tektronix-Thurlby-Time Electronics-TTi-UniT
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf