Issue with mounting KX3 RF board Rev D

[Marcus Busch [DL1EKC]-2]

Hi everybody,

I'm just putting together my KX3 kit. While mounting the RF board Rev D to the
bottom cover I zipped off one of the M-F standoffs using rather little force.
As I usually have a good feeling which force may be used on these standoffs I
started investigating things a bit.

After removing the RF board I callipered the remaining gap after fully
screwing in the M-F standoff into the round standoff at the bottom cover. The
gap is 1.9 mm / 0.075 in. The RF board PCB has a thickness of 1.7 mm / 0.066
in. The lock washer was in place when measuring the gap (see photo). The pan
head screw at the bottom cover has a length of 4.8 mm / 0.0177 in which
matches the numbers in the instruction manual.

Obviously it is not possible to securely mount the PCB to the bottom cover
with the above dimensions. In my understanding those screw points are being
used as grounding points so there should be a reliable electrical connection
as well.

Did anybody here also experience this issue? How did You solve this?

I could use two split lock washers between PCB an M-F standoff, but this would
change the distance between RF board and KXAT3 board and front panel.

Or do I just have bad luck with tolerances?

Any idea or hints are highly appreciated.

VY 73

Marcus, DL1EKC

PS: In case attachments are not allowed, go to
http://www.dl1ekc.de/FTP%20Download/P1080449_640.jpg

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[Phil Wheeler-2]

Marcus,

I had the same experience with a stripped
standoff. It was late on a Friday afternoon as
luck would have it. I called Elecraft and had a
replacement standoff the following Wed. I'm in the
Los Angeles area, reasonably close to Elecraft,
and with quite a few hardware stores nearby. I had
no luck finding a replacement locally. In your
case the wait for a replacement standoff is likely
to be longer than mine -- and that five days was
pretty frustrating, with the KX3 spread out in my
operating position.

I suggested at the time that a spare standoff or
two be included in the kit -- because it is not a
piece of hardware anyone is likely to find in a
local hardware store, and it is pretty easy to
strip, as you and have demonstrated. I guess my
recommendation fell on deaf ears :-)

Unfortunately the only way I could comment on your
measurements and following discussion would be to
disassemble my KX3 and do some measurements -- and
that would risk stripping another standoff with no
spare on hand. Perhaps someone from Elecraft can
comment.

73, Phil W7OX

On 12/6/14 9:39 AM, Marcus Busch [DL1EKC] wrote:

> Hi everybody,
>
> I'm just putting together my KX3 kit. While mounting the RF board Rev D to the
> bottom cover I zipped off one of the M-F standoffs using rather little force.
> As I usually have a good feeling which force may be used on these standoffs I
> started investigating things a bit.
>
> After removing the RF board I callipered the remaining gap after fully
> screwing in the M-F standoff into the round standoff at the bottom cover. The
> gap is 1.9 mm / 0.075 in. The RF board PCB has a thickness of 1.7 mm / 0.066
> in. The lock washer was in place when measuring the gap (see photo). The pan
> head screw at the bottom cover has a length of 4.8 mm / 0.0177 in which
> matches the numbers in the instruction manual.
>
> Obviously it is not possible to securely mount the PCB to the bottom cover
> with the above dimensions. In my understanding those screw points are being
> used as grounding points so there should be a reliable electrical connection
> as well.
>
> Did anybody here also experience this issue? How did You solve this?
>
> I could use two split lock washers between PCB an M-F standoff, but this would
> change the distance between RF board and KXAT3 board and front panel.
>
> Or do I just have bad luck with tolerances?
>
> Any idea or hints are highly appreciated.
>
> VY 73
>
> Marcus, DL1EKC

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