Author Topic: Replacing the infamous Schaffner mains filter on an HP 8561A Spectrum Analyzer  (Read 799 times)

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Offline SMB784

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Howdy everyone, I am looking to replace the Schaffner FN 365-4/01 mains filter on my HP 8561A 6.5 GHz Spectrum Analyzer, as these are prone to spectacular failures.

I need some help identifying which modern mains filter I should replace it with.  I have attached an image of the offending mains filter.  I have found this replacement filter, the Schaffner FN9260A-4-06, and I am hoping that it has the correct specifications, but I was hoping for a bit of help trying to ascertain whether or not it has the same specs.

Anyone have any ideas?
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Offline floobydust

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The old filter shows one-stage with values of 0.8mH, 15nF X-cap, 2.2nF Y-caps, 4A.

The Y-caps are much smaller in your pick, and the X-caps much larger:
FN9260-4-06 is 1mH, 100nF X-cap, 0.47nF Y-caps, 4A and two fuses?
FN261-4-06  is 1mH, 100nF X-cap, 2.2nF Y-caps, 4A and only one fuse.

 

Online NiHaoMike

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It has been a long time since I last opened one, but I recall that by desoldering the ground terminal, the cover slides off and then you can just replace the caps.
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Offline EHT

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I used the following one to replace the filter on my 3457A. It needed a bit of research to find one small enough. I also looked for ones that had some kind of credible fire protection rating. Note that there is a snap-in model and a screw-in model. I accidentally ordered the snap-in as Farnell have the picture of the screw-in on this one. However, it fitted in anyway.

5110-0343-1 - IEC Filter, 47 nF, 250 V, IEC, Mains, 3 A, Quick Connect, 2.5 mH
Manufacturer:   SCHURTER
Manufacturer Part No:   5110-0343-1

http://uk.farnell.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&langId=44&urlRequestType=Base&partNumber=1125792&storeId=10151

http://www.farnell.com/datasheets/1910888.pdf?_ga=2.65374699.438245235.1518512638-2018945104.1508796824
« Last Edit: February 13, 2018, 09:16:11 am by EHT »
 

Offline SMB784

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The old filter shows one-stage with values of 0.8mH, 15nF X-cap, 2.2nF Y-caps, 4A.

The Y-caps are much smaller in your pick, and the X-caps much larger:
FN9260-4-06 is 1mH, 100nF X-cap, 0.47nF Y-caps, 4A and two fuses?
FN261-4-06  is 1mH, 100nF X-cap, 2.2nF Y-caps, 4A and only one fuse.

Thank you for the advice, it is very helpful.  Will the near order of magnitude difference in the x capacitor capacitance between the old model and the new one make any substantive difference in the performance of the power supply, in your estimation?
« Last Edit: February 14, 2018, 12:34:35 am by SMB784 »
"Anything will lase if you hit it hard enough."

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Offline floobydust

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I don't see any penalty having a larger value X-capacitor.
I would not use a smaller 0.47nF Y-caps, I would stay with 2.2nF as I find that is effective.

Down the rabbit hole, the FN332 has the same component values (small 15nF X-cap) as the FN365; comparing (differential) curves to the FN9260, I like the FN261 but not a huge difference.
 


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