David,
I am using a 3.5 mm jack / switch made by Schuter www.schuter.com , their
part number 4302 - 2310 which is the insulated version. I happened to have a
spare new one which I had purchased in Luxembourg, but I believe that
Digikey carry many of Schuter's items.
Apart from being more robust than the existing headphone jack, the internal
switches are more versatile there being one switch on each of the ring, tip
and sleeve 'connections'. Schuter sells a plug designed to mate with this
connector, but as yet I have had no problems when I have had to use a
'standard' 3.5mm stereo plug.
Sorry no pics, but I mounted the jack on the rear panel of the K2 as high as
possible above relay K1 (on RF Board). Although this is perhaps not the best
place for the new jack I did not want to get too close to the Tx driver and
PA to avoid possible RF problems of various types. Having said that my
KPA100 just above has not caused any visible problems. I dispensed with R35,
R36, C105 and C106 and used a length of small diameter 2 conductor sreened
pair to bring the audio 'Hi' and 'Lo' to the new jack. This 'cable' lives
high up on and fixed to the inside of the K2's left hand side panel. To use
the internal speaker you would want at least one extra wire in the
connecting 'cable' to go back from the new jack to the speaker circuit trace
near the existing headphone jack. I would not use the screen for the audio
'Lo'.
If I was going to do it again I just might put the new jack near the K2's
antenna jack and bring the audio from the area of P5 on the right hand side
of the K2. Since putting in the new jack I have found that any additional
objects 'seen' by the Reference oscillator, VCO and BFO on the left can
result in additional problems with receiver birdies and Tx spurs, including
the notorious 7183 kHz flutter. To do this would require a permanent short
between the junction of R35 / R36 and the speaker track going off to P5,
cutting this track close to P5 for connection to the new headphone jack,
with the returning speaker circuit connected to P5.
I hope that this is useful.
73,
Geoff
GM4ESD
----- Original Message -----
From: "David Wilburn" <[EMAIL PROTECTED]>
To: "Geoffrey Mackenzie-Kennedy" <[EMAIL PROTECTED]>
Cc: "Kirk Brown" <[EMAIL PROTECTED]>; "Elecraft Discussion List"
<elecraft@mailman.qth.net>
Sent: Saturday, January 13, 2007 1:39 PM
Subject: Re: [Elecraft] No speaker audio
Any pics of how you mounted and wired it or the part number and vendor of
the part you got to replace it? I'm planning a K2 build soon as I sell
some radios. So I was trying to get the pieces in place from the start.
David Wilburn
[EMAIL PROTECTED]
K4DGW
Geoffrey Mackenzie-Kennedy wrote:
Kirk,
Sounds as though the internal switch in your headphone jack has failed,
and the only practical fix I believe is to replace it. Since 2003 the
switch in the original headphone jack and its replacement in my K2 have
failed, and I now use a robust headphone jack mounted on the rear panel.
73,
Geoff
GM4ESD
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