[Elecraft] K3 - Speaker/headphone problem

[Tom Hammond]

Older K3's were susceptible to damage if a MONO plug was inserted into
the STEREO jack on the back panel.  Subsequent to that, there was both
a hardware and a software mod to new(er) K3s to eliminate the threat of
damage from that happening.

UNfortunately, I cannot quote book, verse, and phrase of exactly when
this 'factory' change occurred.  I believe it's spoken to in the K3
Mods section of the Elecraft web site... QRX... lemme check... OK...
here's the info from http://www.elecraft.com/K3/k3_app_notes.htm and down
at "K3 AF Output Mod Kit. Rev C":

   This modification is needed for all K3s shipped approximately
   before 01/12/09 containing either a Revision "XB" or Revision
   "A" KIO3 board. You must inspect the KIO3 board to see whether
   the modification has been made. Modified boards will include
   the leaded resistors. You can see one of the resistors by
   removing the top cover and inspecting the side of the KIO3
   board facing away from the rear panel. Photos of what the added
   resistors look like are in the document.

Hope this helps.

73,

Tom Hammond   N0SS


At 15:12 01/03/2010, Keith Hamilton wrote:
>Doesn't the manual state that a mono plug is ok? I better unplug my speaker.
>I must have read wrong. Thanks a lot for the post!
>
>Keith W8GX
>
>
>On Jan 3, 2010, at 3:57 PM, Dave Perry N4QS wrote:
>
> > Tony,
> >
> > Same thing happened to me when I plugged my Kenwood mono speaker into the
> > stereo speaker jack on the back of the K3.  I did this without 
> thinking from
> > the front of the radio when I was rearranging equipment in the shack.  The
> > speaker worked for a couple of days until the audio output transistor
> > failed.  I could then only hear audio from the headphones.  I had 
> to send my
> > K3 back to Elecraft in order to replace the audio output 
> transistor.  It was
> > under warranty so they repaired it for free.  While the rig was 
> in the shop,
> > I had them add the sub RX, digital voice recorder, and the IF Out 
> interface.
> > So they came out okay on the deal.
> >
> > But I learned my lesson -- do not plug a mono speaker into the stereo
> > receptacle.  It is clearly labeled as Stereo on the back, but you 
> have to be
> > looking at it from that direction!  Even the manual shows it as stereo.
> >
> > Dave, N4QS
> >
> > ----- Original Message -----
> > From: "N2TK, Tony" <tony.kaz at verizon.net>
> > To: "'Elecraft Reflector'" <elecraft at mailman.qth.net>
> > Sent: Saturday, January 02, 2010 11:25 AM
> > Subject: [Elecraft] K3 - Speaker/headphone problem
> >
> >
> >> Maybe someone has had this problem before and can save me time
> >> troubleshooting?
> >>
> >>
> >>
> >> Everything was fine yesterday. This morning (rig is always ON) headphones
> >> work fine. But nothing out of either internal or external speaker when I
> >> unplugged the headphones. I now have to turn Config: SPKR + PH to YES to
> >> listen out of either an external or internal speaker. But now I can't turn
> >> off the speakers when plugging in the headphones.
> >>
> >>
> >>
> >> Any ideas what could have happened?
> >>
> >>
> >>
> >> Tnx for any feedback.
> >>
> >> N2TK, Tony
> >>
> >>
> >>
> >> ______________________________________________________________
> >> Elecraft mailing list
> >> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >> Help: http://mailman.qth.net/mmfaq.htm
> >> Post: mailto:Elecraft at mailman.qth.net
> >>
> >> This list hosted by: http://www.qsl.net
> >> Please help support this email list: http://www.qsl.net/donate.html
> >
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:Elecraft at mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> >
>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:Elecraft at mailman.qth.net
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html