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<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008>Hi..</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008>Yes the whiskers are a problem, as is already said,
that is why the military, airospace, medical and safety types are still
permitted to use the full fat 60/40 stuff. As is anyone for repairs
to existing equipment.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008>The silver loaded solder was originaly used at Tek
in among other products, the early 500 series 'scopes and accessories
(remember the little reel of the stuff in the 500 series?) so any field repairs
would not weaken the joint between the solder "tag" and the ceramic strip that
held it.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008></SPAN></FONT> </DIV><FONT><SPAN
class=690103514-14102008>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008>As an ex Tektronix type, I spent 3 years doing bench
service and cal's in the UK, at both Harpenden and Maidenhead, starting out
on 'scopes, ending up at one point as "The" person this side of the pond
for Spec' An' repairs and service. Not that I got any
recognition or exra pay when needed....</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2>I remember many
units coming in for rework after a "third party" had been inside with <SPAN
class=690103514-14102008>ordinary</SPAN> 60/40 solder, the joints were fine, but
they had come away from the ceramic, as a casting comes out of a
mold. Reworking them to replace the ceramic strips was a bit of a
chore, to say the least. (And replacing the missing spool of "Tek"
solder!)</FONT></SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008>It was also a "Eutectic" mix, so there was little to no
"plastic" region as it cooled, so making the joint much stronger mechanicaly,
and very "bright" to the eye, aiding quality control, any "Dull" joints were
imediately suspect..</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008>Funny how the "modern" lead free stuff looks like a bad
joint, even when it's suposedly a good one... And how we've tried to
use the stuff for hand assembly. But it's nigh on imposible to get a
reliable joint without a great deal of care and preperation.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008>Thankfully, here in the UK, you can still buy 60/40
Tin/Lead solder (and the silver loaded stuff) from industrial suppliers, so all
is not lost. Yet.....</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008>Happy days...</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008>73.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008>Dave G0WBX.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=690103514-14102008></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT><FONT face=Arial color=#0000ff
size=2></FONT><FONT face=Arial color=#0000ff size=2></FONT><FONT face=Arial
color=#0000ff size=2></FONT><BR></DIV>
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<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> Shanon KA8SPW
[mailto:ka8spw@sbcglobal.net] <BR><B>Sent:</B> 13 October 2008
17:39<BR><B>To:</B> TAPR APRS Mailing List<BR><B>Subject:</B> Re: [aprssig]
Kenwood TH-D7A(G) Retired<BR></FONT><BR></DIV>
<DIV></DIV><TT>Why do you think they came out with silver solder as used in
Tektronics scopes?<BR><BR></TT><!--[if gte mso 9]><xml>
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