|[AMRadio] Ultrasonic feedback|
KC8OPP Roger S.
kc8opp at yahoo.com
Tue Feb 3 07:32:38 EST 2009
Not sure about the Apache, but I do have a Viking II here and the manual tells you to reverse the modulator plate connections if you hear a squeal from the modulation circuit.
Sorry if I am off topic too far.
--- On Mon, 2/2/09, John King <k5pgw at yahoo.com> wrote:
> From: John King <k5pgw at yahoo.com>
> Subject: [AMRadio] Ultrasonic feedback
> To: AMradio at mailman.qth.net
> Date: Monday, February 2, 2009, 9:56 PM
> 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:
> List Rules (must read!): http://w5ami.net/amradiofaq.html
> List Home: http://mailman.qth.net/mailman/listinfo/amradio
> Post: AMRadio at mailman.qth.net
> To unsubscribe, send an email to
> amradio-request at mailman.qth.net with
> the word unsubscribe in the message body.
> This list hosted by: http://www.qsl.net
> Please help support this email list:
More information about the AMRadio mailing list
This page last updated 19 Oct 2017.