[Elecraft] K3 Hardware

[Ron D'Eau Claire]

SCREW BEHIND THE MIC CONNECTOR:

 

The screw in the D2 behind the microphone connector *should* be installed
according to the latest word I have from Wayne.  Leaving screws out can
cause noise/birdie problems through improper ground connections between case
parts and the boards as well as potentially compromise the mechanical
strength of the rig. 

 

TIGHTENING SCREWS

 

Wayne has always specified that power screwdrivers should *not* be used. 

 

How tight is "tight enough" for the screws is a long-standing issue hard to
qualify so everyone understands. Screws are springs. When they are tightened
they stretch slightly to squeeze the parts together. It's a very, very tiny
amount of "stretch" but quite effective and does not require a lot of torque
on the size hardware used in Elecraft rigs. When you feel the torque
suddenly increase as the screw hits "bottom", stop twisting the screwdriver.


 

Certainly one should never tighten a screw so much it's difficult to remove
later. Of course, that presumes you have a  screwdriver that fits the screws
snugly. "Camming out" a screw (in which the screwdriver slips over the slots
and rounds them) is caused by either a poor fitting screwdriver or
over-tightening the screws.  

 

When opening the K3, sometimes you will find that a  screw, particularly one
of the countersunk case screws, that seems to have gotten tighter on its
own. That is usually because tightening the other screws holding that panel
shifted it just enough to bind on one of the screws you already tightened.
When you encounter a screw that seems too tight, first try to loosen the
other screws holding the panel or assembly. Normally you'll find that the
"tight" screw has loosened up after you loosen some of the others. There are
notes about that in the current assembly manuals. 

 

Screws that must be protected from vibrating loose have lock washers.
Over-compressing lock washers does no good at all and can actually prevent
them from keeping the screw in place if they are flattened so much it
weakens the spring action of the washer. 

 

KPA3 FANS

 

Yes, the type of fan used on the KPA3 was changed a number of months ago,
removing the need for the bushings. Installation of the new fans is covered
in the current KPA3 Assembly manual.

 

Ron AC7AC

 

 

From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Roy Morris
Sent: Thursday, February 19, 2009 5:54 AM
To: elecraft at mailman.qth.net
Subject: [Elecraft] K3 Hardware

 

The fans are mounted differently on the new K3s.  The earlier method used
threaded bushing inserts at the corners of each fan.  Flat head screws were
screwed in on each side of the bushings to secure the fan to the plate and
finger screen.  Late model K3s do not use the bushings.  7/8" long flat head
screws are now used, and the fans are secured with acorn nuts.  I presume
these acorn nuts are self locking.  They give the K3 a dressed-up look.

 

I installed a KDVR3 in a factory built K3.  I noticed the rear screw on the
D2 block behind the microphone connector had not been installed, so Elecraft
apparently intends to leave it out to insure adequate clearance when
removing the front panel assembly.

 

The factory built K3 was not purchased directly from the factory.  The
chassis screws were extremely tight.  Either the previous owner had over
tightened them or Elecraft assemblers must be using electric screw drivers.

 

By now you must be asking if I don't have something better to do.  Roy
Morris  W4WFB

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