Thanks Charlie. Good input. 73, John, K5PGW
--- On Mon, 2/2/09, [email protected] <[email protected]> wrote: > From: [email protected] <[email protected]> > Subject: Re: [AMRadio] Ultrasonic feedback > To: [email protected] > Date: Monday, February 2, 2009, 6:16 PM > John: If you can hear the squeal, it is not ultrasonic. That > would be rare > I think. > > Some tubes and their wiring have been known to oscillate at > RF frequencies > which may have several "carriers". The difference > between these carriers may > land in the audio frequency spectrum and be amplified by > the modulator > circuitry. Putting ferrite beads or parasitic chokes in the > grids and plates > of the tubes will not harm anything and may cure the > problem. I have > experienced > this before. > > Loose nuts and bolts on the audio transformers or loose > laminations are a more > likely cause of accoustical feedback. > > Bad inter-stage bypass capacitors allowing electrical > feedback between stages > is the first place I would check. (B+ by-pass caps near the > preamps/drivers). > > Good Luck. Charlie, K0NG > > ______________________________________________________________ > Our Main Website: http://www.amfone.net > AMRadio mailing list > Searchable Archives: > http://www.mail-archive.com/[email protected]/ > List Rules (must read!): http://w5ami.net/amradiofaq.html > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Post: [email protected] > To unsubscribe, send an email to > [email protected] with > the word unsubscribe in the message body. > > This list hosted by: http://www.qsl.net > Please help support this email list: > http://www.qsl.net/donate.html ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
