KPA-500 Question

[Gary Mohrlant-2]

I'm assembling a KPA-500 that I received today and I'm at the step where
I mount the Rectifier bd to the Z-bracket. It looks like the 4 holes for
mounting the rectifiers should be threaded for 4-40 screws but mine has
about 1/8" holes. There is no mention of using a screw and nut to mount
them and there is none provided. I wonder if anyone else has run into
this problem


Gary  W0GHZ
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[Don Wilhelm-4]

Gary,

Try to put a 4-40 screw into the holes.  If it goes through, it is a 1/8
inch hole (clearance for 4-40 screws), but if it must be threaded in,
all is well.  A threaded hole for 4-40 will look almost like a 1/8 inch
hole.
Yes, the holes should be threaded for 4-40.

73,
Don W3FPR

On 3/14/2014 9:44 PM, Gary Mohrlant wrote:
> I'm assembling a KPA-500 that I received today and I'm at the step
> where I mount the Rectifier bd to the Z-bracket. It looks like the 4
> holes for mounting the rectifiers should be threaded for 4-40 screws
> but mine has about 1/8" holes. There is no mention of using a screw
> and nut to mount them and there is none provided. I wonder if anyone
> else has run into this problem
>

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[Doug VE3VS]

On page 23 of my KPA500 assembly manual, relating to the mounting of the rectifier board, it is clear that thermal insulators must isolate the rectifiers from the chassis, and also, that insulating "shoulder washers" must be installed in the four places that you mention as your concern.

The next step, using a DMMeter, checks to determine that there are no shorts between the metal tabs of each rectifier and the bare metal of the Z-bracket.

Undoubtedly, you have already discovered this information in the diagram associated with this part of the assmbly procedure.  ( See figure 29 )

Doug, VE3VS
.....................................................
I'm assembling a KPA-500 that I received today and I'm at the step where
I mount the Rectifier bd to the Z-bracket. It looks like the 4 holes for
mounting the rectifiers should be threaded for 4-40 screws but mine has
about 1/8" holes. There is no mention of using a screw and nut to mount
them and there is none provided. I wonder if anyone else has run into
this problem

Gary  W0GHZ