[Elecraft] Securing Q3 and Q4 on KPA100

[Mike Harris]

Hi,

<SNIP>
The correct part to mount this type of transistor is a dish rim lock washer
but they are hard to find. I used a flat washer and a split lock so the lock
washer is biting into the flat washer not the transistor case. The fibre
washer sounds like a good solution also. I have heard of several cracked
transistor cases because of the lock washer biting into the case of the
transistor.
<SNIP>
Gary Surrency has suggested that Q3 and Q4 be secured to the heat sink with
a
thick fiber washer (like the speaker washer) rather than the split washer
that can bite into the plastic transistor body and damage it.  Fiber washers
about the size of the speaker washers can be found at Home Depot.  The
washers to use are the #4 x .032".  The hole in these washers are slightly
larger than the screw diameter which should let the washer seat properly if
the transistor is not in perfect alignment with the PCB hole.  I am not
using
the split washer on top of the fiber washer, and I don't believe Gary uses
the split washer on top of the fiber washer either.  If these screws are
tightened with normal torque, they will stay put.
<SNIP>

Useful.  I used a couple of spare tooth lock washers from the
various K2 options.  Much less savage than the split washer.

Regards,

Mike VP8NO (IOTA SA-002)
GQRP 10148
K2 #1400