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EF86 36 watt start up buzz
Posted: Sun 03/10/13 1:12 pm
by POWDOG
Hi all. Just bringing up a new 36 watt build with EF86 preamp. At about 50 volts on the variac I've already developed a buzz. Sounds like 60 Hz, not filter hum. Ideas where to start looking? Thanks.
Re: EF86 36 watt start up buzz
Posted: Tue 03/18/14 6:48 am
by dotfret
Try grounding the EF86 screen via a 0.2 uF paper capacitor, and read the other hints in the application notes on this data sheet -
http://www.mif.pg.gda.pl/homepages/fran ... 29_GEC.pdf" onclick="window.open(this.href);return false;