[Elecraft] K3 - No speaker output

[Mel Farrer]

Sorry, but the only solution to keep the two outputs isolated is to provide two audio output jacks, one for left and one for right. AND have a appropriate limiting coupling cap or series limiting regulator for the amp.  IMHO.

Mel, K6KBE





On Tuesday, January 14, 2014 6:13 PM, Dave Hachadorian <k6ll.dave at gmail.com> wrote:
 
Putting a mono plug into the stereo jack is not the ONLY failure
mechanism for the speaker amplifier chip.  It was not the cause
of failure of my two K3's.

I'm not sure anyone fully understands the failure
mechanisms in the speaker amplifier.

The new $2.36 mod adds 1 ohm resistors in series with the audio
output channels.  Hopefully that will do some good.

Dave Hachadorian, K6LL
Yuma, AZ



-----Original Message----- 
From: Don Wilhelm
Sent: Tuesday, January 14, 2014 5:10 PM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3 - No speaker output

Dick,

If you have an early K3 *and* you plugged a mono connector into
the rear
speaker jack, one channel was shorted by the mono connector. That
will
cause failure of the audio amp for the speaker.
Later K3s (I don't know the serial number) have protection for
that
shorting condition.  The best protection is not to put a mono
plug into
the speaker jack.  If you want mono, cut off the mono plug and
connect
only the tip and shell to your speaker - the ring does not
connect to
anything.

73,
Don W3FPR

On 1/14/2014 6:55 PM, Richard Solomon wrote:
> Can someone explain to me exactly why the chip failed, and what
> the Audio
> Protection Assembly is for ?
>
> Tnx, Dick, W1KSZ
>

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