Does it happen with the microphone disconnected? Bob Macklin K5MYJ Kent (Seattle), Wa, "Real Radios Glow in the Dark"
----- Original Message ----- From: "John King" <[email protected]> To: <[email protected]> Sent: Monday, February 02, 2009 6:56 PM Subject: [AMRadio] Ultrasonic feedback > Can anyone direct me to a source of information or a tutorial on Ultrasonic feedback in modulator circuits such as that in the Heathkit Apache. > > My Apache modulator squeals when the microphone gain is raised and the modulator tubes draw a lot of current. As long as the microphone gain is kept very LOW the current does not take off and there is no squeal coming from the modulator section. I am going to go through the section with a screwdriver and a nut driver to tighten up the grounds to the chassis and tube socket. > > Ultrasonic feedback is a NEW phenomenon to me. Someone mentioned ferrite beads some time back. Thanks for reading. 73, John, K5PGW > > > > > > > ______________________________________________________________ > 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
