[Elecraft] K3: Right paddle key not working?

[Gene Langendorff]

James,

 

Sorry I didn't get back to you sooner but I was out of the house to a
birthday dinner (mine).

 

I'm pleased that you were able to find the source of your problem.  But I'm
REALLY SORRY that your attempted repair apparently destroyed the RFC.  In my
case, the SOLDER CONNECTION between the RFC and the solder pad was open, and
by reflowing the joint with fresh solder - and a little pressure to make a
firm connection - the problem was resolved.

 

In re-reading your response, I think you thought the choke itself was open.
I'm sorry if I misled you.  Perhaps I should have been more careful in my
phrasing.  At any rate, Steve's suggestion of using a piece of wire to short
out the choke, should get you going for now.  Then when a new part comes
from Elecraft, you can install the new one.  Mind you, it's tedious work
working with those REALLY tiny surface mount parts.  But if you're careful,
it can be done.  Be sure to use a very small tip and a temperature
controlled solder station.  We don't want to damage anything else.

 

Start by cleaning all of the old solder from the pads.  Use a solder sucker,
solder wick and fresh solder on your iron to do that.  Once cleaned in that
manner, you'll have a nicely cleaned pad with easily flowed fresh solder.
Now prepare the new part by tinning its connecting surfaces.  You will then
have fresh solder on the part which will quickly and easily flow with the
fresh solder on the pad.  DO NOT use a lot of solder.  Just a thin film is
sufficient.  You don't want to have one end of the part attached to the pad
and the other end tilted up on a mound of solder.

 

To solder the part to the pads, place the part in its place and hold it down
with a toothpick or something similar.  (That requires the use of one hand.)
Don't let it move while soldering.  Then, using the other hand, wet the tip
of the iron with solder and apply the tip to the JUNCTION of one end of the
part and its associated pad, heating both the part and the pad
simultaneously.  When properly heated, the solder will flow into the joint
and when the iron is removed will cool to a nice firm connection.  Don't let
anything move while it's cooling!  To do so will result in a cold solder
joint and you will have to start over.

 

Now that you have one end of the part secured, the rest is easy because the
first end of the part is being held in place by solder.  Merely wet the tip
of your iron with solder again and applying pressure on the second end of
the part with your toothpick, solder the second end as you did the first.
Remember to apply the tip of the iron to the JOINT, so that you heat both
the end of the part and the solder pad at the same time.  The solder will
flow into the joint when properly heated.  Congratulations, YOU'RE DONE!  If
it would make you feel better, you can apply a small amount of additional
solder to the joint but it's really not necessary.

 

Hope this helps.

 

73,

Gene K6TTM

 

 

From: James Sarte [mailto:k2qi.nyc at gmail.com] 
Sent: Saturday, November 13, 2010 7:56 PM
To: Gene Langendorff
Cc: don at w3fpr.com; Elecraft
Subject: Re: [Elecraft] K3: Right paddle key not working?

 

Gene et all,

 

I reheated the contacts on RFC4 to the point that I think I even slightly
warped the casing of the choke on one side.  No good.  No continuity at all
from any of the trace points or direct contact with the chokes leads.

 

Looks like RFC4 is dead and K3 #2730 will have to go back to Aptos for
repair.

 

73 de James K2QI

On Sat, Nov 13, 2010 at 10:02 PM, James Sarte <k2qi.nyc at gmail.com> wrote:

 

On Sat, Nov 13, 2010 at 9:04 PM, Gene Langendorff <k6ttm at sbcglobal.net>
wrote:

I had the same symptom on my year old newly completed K3 kit a few months
ago (S/N 3172).  With Gary's guidance found the trouble to be one of the
surface mount chokes (RFC3 or RFC4) between the paddles jack (J12) and the
board needed resoldering.  Check for continuity with your ohmmeter and you
will probably find one of them not connected.  Carefully resolder each end
while applying downward pressure, one end at a time, and it should work.

Gene K6TTM


 




-- 

73 de James K2QI

President UNARC/4U1UN