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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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25th Apr 2017, 4:11 pm | #1 |
Octode
Join Date: Jul 2014
Location: Petersfield, Hampshire, UK.
Posts: 1,043
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Murphy A100 microphony
Hi All,
I have a problem when any valve is slightly tapped except v1 there is microphony. This can be heard even with v/c at zero It gets worse when in its cabinet ! Anyone had this with this radio please ? Cheers Pete |
25th Apr 2017, 4:44 pm | #2 |
Octode
Join Date: Nov 2010
Location: Cullompton, Devon, UK.
Posts: 1,434
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Re: Murphy a100 microfony
So the problem would seem around 10LD11 & 10P13, firstly have you changed any capacitors such as C19 decoupling or C20 coupling capacitors ?.other than that you could short grid one to chassis on the 10P13, if it is still there probably a noisey 10P13 if not then 10LD11 could be the culprit .
John |
25th Apr 2017, 6:41 pm | #3 |
Octode
Join Date: Jul 2014
Location: Petersfield, Hampshire, UK.
Posts: 1,043
|
Re: Murphy A100 microphony
Hi John,
I have re cap the whole radio so I don't think it's decoupling I'll try shorting the grids The performance is not good at all but looking at threads I think it was this way unless it has a decent aerial .Def not one in the mains lead ! Cheers Pete |
26th Apr 2017, 8:01 pm | #4 |
Octode
Join Date: Jul 2014
Location: Petersfield, Hampshire, UK.
Posts: 1,043
|
Re: Murphy A100 microphony
Hi John,
It was v3 the det/amp valve causing the problem. Cheers Pete |