[Elecraft] K2 headphone jack

[drewko1 at verizon.net]

On Sun, 23 Sep 2007 10:05:29 -0700, Leigh/WA5ZNU wrote:

>
>While some say the jack fails due to downward pressure and others say it 
>fails due to repetitn, lately some think that the switch in the jack is 
>damaged by excessive heat during soldering, so I tried to solder it as 
>quickly as I could this last time, and also I installed a fixed-level 
>audio out board for digital modes, so that I wasn't tempted to plug in 
>the headphone jack when I didn't really need to.
>

There is a contact that slides across the three rear pins of the jack.
If soldering is the problem, it is those three pins to watch out for.
This contact is definitely the weak point of the switch.

See my earlier post to this forum ("Lost speaker audio in K2")
regarding installation of a headphone/speaker switch; then you can
leave the headphones plugged in all the time and just use the switch.
In any case, the switch is a lot more convenient. (Seems like I was
forever hitting the NB button when trying to get the plug out...)

If you want to add a switch the time to do it is while replacing the
jack becuase you have to bend one of the jack pins out of the way
before installing it.

Here are comments I sent to someone who asked me about it:

> The switch I used was p/n: 8011 from Web-tronics. It is a DPDT
> (on-x-on) miniature size. I bought it along with their budget
> soldering station-- a nice unit.
>
> http://www.web-tronics.com/index.html
>
> I'm sure you can find similiar switches at Mouser:
>
> The mini-size switch mounts securely with the supplied hardware in the
> rig's Transverter hole, below the speaker jack. I figured that if I
> ever get a transverter I'll worry about moving it then. If you're
> going to drill your own hole for the switch you might consider getting
> a sub-mini switch. As it is, mine doesn't interfere with my K2 options
> (antenna tuner & noise blanker).
>
> One pole of the switch is wired to the ground pin (center, forward) of
> the jack (bent flat, as mentioned), and to its mating pad on the
> circuit trace.
>
> The other pole (and opposite throw) is wired across two of the three
> rear pins on the jack body-- I can't remember which two at the moment.
> Actually, it is not wired directly to the pins but tack soldered to
> their circuit pads.
>
> I used a round 4-cond cable, routed as mentioned. But you might want
> to try flat ribbon cable instead. Maybe that will be able to sqeeze
> past the board to the rear compartment; you better check first to make
> sure there is enough clearance.
>
> Now, I think all of that is correct, but If any questions, please ask.


As for which of the three rear jack pins are wired to one of the
switch poles (mentioned above): With the jack flat on the table, hole
facing you, pins pointing up, it's the rear-right pair of pins.

73,
Drew
AF2Z