[Hallicrafters] SR-2000 post production change

[Carl]

Any high power amp will crystalize standard Tin-Lead solder over time; 
Hallicrafters is not unique. Solder has a finite amount of resistance to 
RF.  The simple cure is to remove all of the solder and flow in new and 
dont worry for another 10-20 years. Or use real silver solder.

Carl
KM1H


----- Original Message ----- 
From: "Jim Liles" <james.liles at comcast.net>
To: <hallicrafters at mailman.qth.net>
Sent: Thursday, January 29, 2009 11:12 AM
Subject: [Hallicrafters] SR-2000 post production change


> Good morning:
> We have discovered a design flaw in the final configuration of the 
> SR-2000.
> Capacitor C156A is the solo loading cap, bearing 100% of the unloaded
> current when using the 10 meter band and bears more than 1/2 the load 
> when
> using the 15 meter band.  Every SR-2000 that we have inspected has
> experienced over heating at that connection.  To check your SR-2000 
> simply
> use a mirror and flashlight to confirm that the connection has 
> actually
> melted the solder or worse.  This connection is used on all bands but 
> solo
> on 10 meters  The best description of the effect is the radio is 
> squirrely
> when loading and tune up as a result of the unreliable solder joint.
> The fix is to remove the capacitor by clipping the wires which can be
> spliced using #16 id copper tubing from a hobby shop, sliding the lock 
> ring
> back on the tuning shaft --- it is not in a groove, slide the coupler 
> to the
> front,  remove three mounting screws and tip the rear of the cap to 
> the left
> of the radio.  The existing wires in the final cage will not solder 
> with out
> sanding, too many years on the tin.  I would replace those on the cap 
> and
> sand the partners before inserting into the copper couplings when
> reinstalling.  To fix the connection, find a short, I believe 10/32 
> screw, a
> piece of copper strap, and some silver base solder.  Tin the strap 
> then
> gently screw the copper strap to the phenolic holding it to the stator
> phalange.  Reinsert the removed or new #16 wire into the original tab 
> and
> wrap the copper strap over the wire and silver solder all.  It will be 
> clear
> when you see the connection up close.  We made this change and after 
> several
> hours of operation on 10 meters the joint was cool.  If you need
> clarification or photo's  please email or call 847-571-8420   Kindest
> regards Jim K9AXN
>
>
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