| Products > Test Equipment |
| HP/Keysight 66311B magnetic field leakage |
| (1/8) > >> |
| Gulftown:
Hello, i've recently bought a used HP 66311B Mobile Communications DC Source from around 2003, which is working pretty well. But when i power it on, the case of the supply is making a relatively loud hum and when i place it near my crt oscilloscope the whole picture is shaking wildly. The Souce needs to be at least 40 cm away from the scope to not distort the screen. Thats why i suspect excessive magnetix flux leakage from the transformer. Has anyone else the same problem? Any tips on how to improve the situation? It's very annoying, because i want to use the scope and the supply on the same eqipment stack. I already removed all the secondary connections from the transformer, but its still happening. Greetings from germany |
| beatman:
one solution is to separate the trans from enclosure to another metal box under your work desk and do the connections with thick cables to the main unit.one other try is to cover carefully the transformer with copper or iron foil to isolate the flux that escape.i am not sure that works.may you get some more options from other guys here. |
| BlownUpCapacitor:
What beatman said is correct. Adding an EMI shield will definitely help. Use copper tape to make a strap around the switching transformer as shown in the image. Then ground it. If that doesn't work you can try using mu-metal shielding to stop EMI. https://en.wikipedia.org/wiki/Mu-metal Though I'm not too sure of its effectiveness at high frequencies... maybe someone can answer that for me. Edit: Shouldn't the analog scope have mu-metal shielding already though? |
| AVGresponding:
WTH! This is definitely not normal, mine does not do this. The only noise it makes is the fan, which only gets annoying when you load it up a bit. |
| Gulftown:
--- Quote from: BlownUpCapacitor on November 16, 2023, 06:51:02 pm ---What beatman said is correct. Adding an EMI shield will definitely help. Use copper tape to make a strap around the switching transformer as shown in the image. Then ground it. If that doesn't work you can try using mu-metal shielding to stop EMI. https://en.wikipedia.org/wiki/Mu-metal Though I'm not too sure of its effectiveness at high frequencies... maybe someone can answer that for me. Edit: Shouldn't the analog scope have mu-metal shielding already though? --- End quote --- I will try it, thanks. I found some mu metal foil on ebay. Its a Tektronix TDS460A, so not even a bad scope. But still... --- Quote from: AVGresponding on November 16, 2023, 06:53:50 pm ---WTH! This is definitely not normal, mine does not do this. The only noise it makes is the fan, which only gets annoying when you load it up a bit. --- End quote --- I thought so, but what can be the issue, when the supply is working normally, the voltages are matching and the transformer is leaking, even under no load. It must either be some kind of production issue, or the core of the transformer is broken internally and the flux needs to jump an air-gap or whatever. |
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