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Date: Sun, 4 May 2003 13:31:50 -0500
Subject: Re: [Elecraft] K1 sidetone overpowers headphones
Cc: elecraft at mailman.qth.net
To: Robert J Greenwalt Jr <rgreen2 at pacbell.net>
From: Dave Gingrich K9DC <gingrich2 at dcg.org>


On Sunday, May 4, 2003, at 09:04 EST, Robert J Greenwalt Jr wrote:

> Don't know if this is an unusual situation or not -- My K1 works fine 
> on
> speaker but when I plug in a set of Bose noise cancelling phones the
> sidetone during keying becomes an overwhelmingly loud crashing tone in 
> the
> phones.  Its almost painfully loud.  When I set the K1 output to zero 
> the
> keyer sounds fine in the headphones.  When I turn the power back up to
> actually transmit, I get the crashing effect.  Reducing the StL level 
> has no
> effect.  The Bose phones have an audio amplifier in the line to 
> produce the
> noise cancelling effect -- could RF be causing this?

Probably yes. I also have the same Bose headphones. Totally useless 
anywhere near anything resembling RF.

===========================
Dave Gingrich, K9DC
Indianapolis, Indiana USA
===========================

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Reply-To: <la3za at qsl.net>
From: "Sverre Holm - LA3ZA" <la3za at qsl.net>
To: "'Dave Gingrich K9DC'" <gingrich2 at dcg.org>,
        "'Robert J Greenwalt Jr'" <rgreen2 at pacbell.net>
Cc: <elecraft at mailman.qth.net>
Subject: RE: [Elecraft] K1 sidetone overpowers headphones
Date: Sun, 4 May 2003 20:42:39 +0200

I also have noise cancelling phone which hum during transmission if the
noise cancelling is on. It almost disappears if I wind the cable many
times through a toroid core that I had lying around, it is about 25-30
mm outer diameter I would guess.

73, 
Sverre

------------------
Sverre Holm, LA3ZA
www.qsl.net/la3za

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Date: Sun, 4 May 2003 13:22:53 -0700 (PDT)
From: Daniel Reynolds <aa0ni at yahoo.com>
Subject: Re: [Elecraft] K1 sidetone overpowers headphones
To: elecraft at mailman.qth.net

I had a similar problem with my noise reduction Bose headphones and my K2 until
I did the following...

I bought an RF choke (two halves of a rectangular ferrite core and a pastic
case that holds the two halves together) from Radio Shack and wrapped up the 3'
accessory cord that came with the Bose headphones completely in the RF choke.

It seemed to help quite a bit!

I guess that the audio line into the noise reduction device was picking up
stray RF from the K1/K2.

- Daniel/AA0NI

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