[Elecraft] Securing Q3 and Q4 on KPA100

Fri Aug 16 16:27:00 2002

Hi

The correct part to mount this type of transistor is a dish rim lock wash=
er but they are hard to find. I used a flat washer and a split lock so th=
e lock washer is biting into the flat washer not the transistor case. The=
 fiber washer sounds like a good solution also. I have heard of several c=
racked transistor cases because of the lock washer biting into the case o=
f the transistor.

Don Brown
KD5NDB

----- Original Message -----
From: [email protected]
Sent: Friday, August 16, 2002 1:44 PM
To: [email protected]
Subject: [Elecraft] Securing Q3 and Q4 on KPA100

Gary Surrency has suggested that Q3 and Q4 be secured to the heat sink wi=
th a =20
thick fiber washer (like the speaker washer) rather than the split washer=
 =20
that can bite into the plastic transistor body and damage it.  Fiber wash=
ers =20
about the size of the speaker washers can be found at Home Depot.  The =20
washers to use are the #4 x .032".  The hole in these washers are slightl=
y =20
larger than the screw diameter which should let the washer seat properly =
if =20
the transistor is not in perfect alignment with the PCB hole.  I am not u=
sing =20
the split washer on top of the fiber washer, and I don't believe Gary use=
s =20
the split washer on top of the fiber washer either.  If these screws are =20
tightened with normal torque, they will stay put.  Roy Morris  W4WFB  K2/=
100 =20
#2225 =20
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