Wrong PIM nuts in KPA500 kit

A 4-40 PEM nut typically requires a .166 diameter hole and a 6-32 requires a
.188 hole. So if a 4-40 nut was installed in a.188 hole it will not grip the
material properly and it will eventually fall out. You should not re-tap the
threads to correct the problem or use a smaller screw. You can install PEM
fasteners with a hammer and anvil however there are insertion machines
designed for this task.

John KK9A

Michael Blake <k9jri at mac.com> wrote:

I received a call back from Elecraft Technical Support yesterday.  It was
quite difficult to come together on exactly which screws and embedded PEM
nuts I was talking about in the bottom cover.  Once we were in agreement
on the screw positions I was talking about the technician looked at a
bottom cover but was unable to determine the exact thread sizes as he was
unwilling to remove the green protective tape which covered the holes.  He
was not really equipped to handle this mechanical sheet metal problem but
was going to refer it to another group which could more easily address the
problem.  I initially got the impression that he thought that I was
incorrect about the threaded nut (PEM nuts)  error but I think we got past
that.

For clarification, if you have a new kit and would check, these are the
steps where the problems arise:

These are the steps in the Kit Assembly Instructions

Page 15, figure 14 show six (6) 1/4" 6-32 BLACK FLAT HEAD SCREWS. The
right hand two (2) 6-32 screw locations were equipped with 4-40 threaded
nut inserts (PEM nuts) rather than the correct 6-32 threaded inserts (PEM
nuts).  The two (2) 4-40 BLACK FLAT HEAD SCREW shown in this figure were
correctly equipped with 4-40 threaded inserts (PEM nuts).

The same problem exists on the right hand side cover.

Page 24, figure 32 instructs you to install four (4) 6-32 BLACK FLAT HEAD
SCREWS.  In this case the two rear 6-32 screw locations were equipped with
the correct 6-32 threaded inserts (PEM  nuts) but the front two locations
were equipped with 4-40 threaded inserts (PEM nuts).

At this point I am waiting to see what they find when they check their
current supply of bottom covers and what their recommendation will be to
correct the problem.

I do have a photo but I do not believe I can attach it to the reflector.

Michael Blake
k9jri at mac.com

On Jan 27, 2018, at 11:06 AM, Michael Blake <k9jri at mac.com> wrote:

I am waiting on a response from Elecraft TS on this one but I thought I
would ask if anyone else has encountered this problem on the KPA500 kit.

On the bottom edge of both the right and left side panels there are places
for three 6-32 flat head screws. The countersunk holes are obviously
larger than those for the other 4-40 flat head screws.

In my kit one of the three PIM nuts, for each side, was the correct 6-32
thread PIM nut and the remaining two had 4-40 PIM nuts installed in the
bottom cover. When I had temporarily installed the left hand side panel in
the middle of construction I failed to notice this and just installed
screws that fit (one 6-32 and two 4-40) but during final assembly it
became obvious that the 6-32 screws would not fit in 4 of the 6 positions.

Thinking that they just had paint in them I tried tp run a 6-32 tap
through one and it naturally seized up and twisted the PIM nut out. Not
being the brightest bulb in the shop I tried that a second time and
twisted out the second PIM nut.

Fortunately these were both on the right hand side where there was room to
slip two 6-32 hex nuts in place and I just used two 4-40 flat head screws
on the left side.

Hopefully Elecraft will be able to send me the correct PIM nuts to replace
the four incorrect ones. That was my request in the email to Doug at tech
support.

I certainly would not want to replace the bottom coverl as that would
require a complete disassembly of the amplifier.

Has anyone else encountered this?

Michael Blake
k9jri at mac.com

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]