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Old 1st Dec 2022, 8:12 pm   #26
frsimen
Heptode
 
Join Date: Jan 2011
Location: Croydon, London, UK.
Posts: 773
Default Re: Cossor 524 rustling noise on FM

Could this be leakage from the HT on the valve holder? Such leakage will cause the loudest noises with the volume control near the mid setting. At higher and lower settings, the impedance seen by AC component of the noise at its lowest, so the noise will be reduced.

Try cleaning the EABC80's valve holder with a solvent to remove anything which may be causing leakage. If that doesn't help, try a different EABC80.

Paula
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