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Old 3rd Feb 2021, 3:32 pm   #1
vinrads
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Default Mains filter .

I have just got round to trying this filter I purchased a while back, the KB FB10 was on the bench connected via an isolating TX. On LW there was the usual racket, the filter reduced it to almost nothing.

for the filter.

Mick.
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Old 3rd Feb 2021, 3:48 pm   #2
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Default Re: Mains filter .

They look nice in those cans, don't they? But be aware that inside there are some of those X type paper capacitors famous for going up in foul smelling smoke.

I replaced a filter in a sig gen a while ago and the capacitor conflagration had burned through the tinned steel can.

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Old 3rd Feb 2021, 3:54 pm   #3
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Default Re: Mains filter .

Those are good when new but after about 10 years old or more they start to get a bit aggressive and will eventually hit you on the nose with a bit of a whiff
I can't see an obvious date code on the one in the photo.

Edit.
David is right. I have seen a photo of a RIFA that had been dug out of the ashes of one.
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Old 9th Apr 2021, 1:18 pm   #4
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Default Re: Mains filter .

In the past I have fairly successfully dealt with mains borne interference with a simple class x cap across the mains. Recently I have been getting all sorts of weird warbles and noises from mains powered AM radios. I suspect next door's TV set but I have no evidence of that!

Anyway I have been considering getting a couple of mains filters for the sets that get the most use. There are several on the market going up to ones costing well over £300 which will improve the musicality of your hi-fi - apparently!!

Are these Schaffner ones still regarded as unreliable and if so would a different type be better? Any recommendations?

Thank you
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Old 9th Apr 2021, 4:16 pm   #5
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Default Re: Mains filter .

That filter has two different winding arrangements for the chokes.

I don't often see that in mains filters.
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Old 9th Apr 2021, 5:26 pm   #6
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Default Re: Mains filter .

We have been using these Schaffner filters for 30 years or so failure rate is tiny.

Failure is usually after "an event" and usually results in the filter going open circuit on one of the poles.

As far as I know they haven't used paper capacitors for 4 or more decades.

I cut one open in 2014 and the Caps were Metallized Polyester Film Capacitors and they were held in place but not totally encapsulated in a resin.

https://www.radios-tv.co.uk/communit...lots-of-smoke/

Cheers

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Old 9th Apr 2021, 6:23 pm   #7
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Default Re: Mains filter .

Schaffner have a very good reputation. Certainly the older ones now suffer from paper capacitor problems, but Schaffner are the sort of firm that once they found out about it, would do something about it. THey also make surge and transient generators for the sort of tests which would eventually find these problems.

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Old 9th Apr 2021, 6:57 pm   #8
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Default Re: Mains filter .

Thank you for the replies. I will buy one to see whether it improves the interference problem.
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Old 13th Apr 2021, 6:13 pm   #9
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Default Re: Mains filter .

Well, it arrived today and I connected it up but unfortunately it makes no difference at all to the warbling interference!
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