[Elecraft] K3 Headphone jack/front panel gap

[Ron D'Eau Claire]

I've only received sporadic reports of this happening, and *nothing* after
suggesting checking the fit of the mic connector, which led me to believe
the problem was fixed as suggested. I appreciate those who are taking the
time to say otherwise! 

I did a little research today with people building K3s in Aptos and handling
some that were returned for various reasons. 

As Terry noted, it's possible there is a variation in the thickness of the
washers supplied that is getting past the folks doing receiving inspection.
So far, while building K3s, they have yet to encounter a single unit that
didn't fit correctly. However, they are seeing several things that might
cause the problem.

Among the returns they have noticed several that did not have the split ring
lock washer between the standoff and the pc board as shown in Figure 34 of
the assembly manual. Instead the builder put the washer under the head of
the screw because that’s where one might expect to put a lock washer, but
that is *not* where it goes. In this case it is part of the total spacer
provided by the standoff and must go between the standoff and the pc board.
That mistake actually helps the PHONES washer fit more tightly by moving
everything forward toward the sheet metal, but can result in a skewed VFO A
shaft since the connector 'bottoms out' in the jack on the front panel PC
board before it sits squarely behind the front panel. Adding the nut inside
the front panel will move the VFO A encoder back and solve that problem, but
it can cause fit issues in the future as you add options. 

Another problem that mistake causes are occasional broken LCD glass because
the display is moved forward with the front panel board where the screws
holding the LCD cover can strike it.

So far, they have found they can fix loose PHONES jack washers and crooked
VFO A encoders by tightening the nuts sufficiently. As one builder
mentioned, the knurled nut defies too much tightening with a tool unless one
risks scratching the front panel. What the folks in Aptos have done is to
squeeze the front panel sheet metal back against the PC boards in one hand,
pressing *between* the jack and the red and yellow LEDs just above it (but
not ON the LEDs) with a thumb while supporting the PC boards with their
fingers from behind. That flexes the sheet metal just slightly but enough to
allow them to tighten the PHONES knurled nut with the fingers of the other
hand to trap the washer securely. So far, that has cured all the loose
washers they have encountered assembling rigs. 

They also reported getting a few K3s back with complaints about a crooked
VFO A encoder that was fixed simply by tightening the nut against the front
panel. It was finger tight, but not tight enough. A little extra leverage on
the nut straightened up the shaft. 

Of course, both of those "fixes" can cause serious damage if the front panel
is not properly spaced from the front panel board using the 5/16" standoffs
and split lock washers as shown in the manual. 

An obvious question is "how tight is too tight" so that it might break
something. I have assembled two front panels, and both times nominal
pressure with pliers (or a socket wrench held in my hand - no handle
attached) was plenty. But two is a tiny sample. It would be good to hear
from those who have the "loose Phones washer" and "crooked VFO A encoder"
problems and whether any of the above helped, should you be inclined to take
another look.

Feel free to drop me a note if you're experiencing these problems and let me
know if the above help. 

Ron
ron at elecraft.com 



-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Terry Schieler
Sent: Tuesday, April 29, 2008 8:37 AM
To: elecraft at mailman.qth.net
Subject: [Elecraft] K3 Headphone jack/front panel gap


Chuck, AE4CW, posted:

" Ron, I too had the headphone jack problem.  After talking with tech
support I reveisited the assembly and am certain it's perfect, but there is
still a gap between the shoulder of the headphone jack and the front panel.
I measured it with a shim guage but, unfortunately have forgotten the
number. 
In any case I found a thin washer (from another 1/4" jack) that filled the
gap perfectly and intalled it over the jack threads behind the panel. 
Perhaps there was as parts variation from the vendor that could account for
the gap."


Chuck et al....

I had the exact same issue with the headphone jack and the "thick washer"
used to space it from the front panel.  Everything has been checked and
double checked and the thick spacing washer still rattles between the board
mounted headphone jack and the front panel.

I posted my concern here months ago and received responses like Chuck did
above.  On the other hand, I received half a dozen direct emails from other
K3 owners who experienced the loose spacing washer.  All seemed to feel that
their fitting of the front panel was correct in every other area.

I think it's an issue other than a poorly fitted front panel or binding mic
connector.

My 2 cents.

Terry, WØFM
K3/100 #474