[Elecraft] K3 - KPAIO3 'Puller'

[Tom Hammond]

Recently, I had to open up my K3 in order to perform a bit of 
preventive maintenance, on the KPAIO3 PC board.  This is the small PC 
board which interfaces the KPA3 100W amp assembly to the RF board in 
the Elecraft K3 HF transceiver.

The job started off easy enough... remove the top cover, remove the 
rear cooling fan assembly, remove the KPA3 PC board... I mean, it was 
an easy thing to do... a small PC board... couldn't be all THAT 
difficult to pull it straight up and out of the case, 
right?  WRONG!  In order to ensure that the KPA3 doesn't accidentally 
come loose during transport and handling, Elecraft chose to use some 
REALLY husky dual-row multi-pin 'hi retention' headers to attach the 
KPAIO3 to the RF board, and the same headers to attach the KPA3 to 
the KPAIO3.  The only difference is that if you must remove the KPA3 
from the clutches of the KPAIO3, you have a bit more available 'real 
estate' to grasp (and pry) on than you do when it comes to removing 
the KAPIO3 board.  In fact, there was a point in time that I was 
absolutely certain that my KPAIO3 had been soldered directly to the 
RF board, it was that tightly held in place.

Before I went too far and found myself ripping the guts of the RF 
board out (because my KPAIO3 really WAS soldered to the RF board), I 
called Elecraft and spoke with one of their techs who was very 
familiar with the K3.  Let me digress just a bit here... I did build 
my K3 from a kit, but being serial #00008 (and one of the first K3's 
out of Aptos), it had been quite a while since the assembly, and I 
didn't recall whether I'd installed my KPAIO3 or whether it'd been 
pre-installed at the factory... so I called to confirm my 
suspicions... that it really DID plug in.

The tech assured me that it did plug into the RF board and he agreed 
that it was a 'bear' to remove.  He suggested 'wiggling' the PC board 
(front-to-back) as I lifted it up, ever so gradually allowing it to 
'work' itself out of the death grip of the two headers.  I considered 
that scenario, but didn't care for the 'wiggling' part, feeling that 
this only contributed to a possibly fractured PC board joint on one 
(or more) of the header pins...

The tech also suggested using some 'heavy wire' to make a loop to go 
through two (2) available  (and unused) holes in the KPAIO3 PC board, 
with the loop tied together so I could lift on it and pull the PC 
board straight out.

THIS IDEA I LIKED...!

I did a quick search of the shack and found little heavy wire, BUT I 
did manage to locate what turned out to be a length of 0.125" (1/8") 
O.D. aluminum welding rod.

I checked that the rod just barely passed through the (2) holes in 
the KPAIO3 PC board and was gratified to find that it did.

I then took a few measurements and bent the rod into the lift bracket 
shown below (note that the two vertical legs are different lengths), 
cutting off the excess rod length after the final bend had been 
made.  I then used a fine file to smooth out any 'dings' I might have 
created in the two short 'feet' of the lift bracket, to ensure that 
they would insert easily into the two PC board holes.

Now, all I have to do is to slip the two 'feet' of the lifting 
bracket into the holes of the KPAIO3 PC board, grip the lifting 
bracket AND the top bar of the K3 rear panel and squeeze my 
hand!  The PC board pops out cleanly and quite easily.  And much more 
safely than were I to have to 'wiggle' things back 'n forth.

While I don't expect everyone to have 1/8" O.D. aluminum welding rod 
on hand, I'm pretty certain that the same device could be made using 
a fairly heavy gauge metal clothes hangar.  The IMPORTANT thing is, 
when using this device, keep the main body of the lifting bracket up 
flush against the PC board,  thereby reducing the stress on the feet 
and keeping them from bending.

A PDF with this article and dimensional illustrations of the KPAIO3 
Puller is available on my web site at:

   http://www.n0ss.net/index_k3.html

more specifically:

   http://www.n0ss.net/kpaio3_pcb_puller_v1r1.pdf

73,

Tom Hammond   N0SS