Meat Plow wrote in
:

On Sat, 19 Jan 2008 10:35:41 +0000, Arfa Daily wrote:


"robb" wrote in message
...

"James Sweet" wrote in message
news:wZ8kj.2039$5h6.1213@trndny09...

"robb" wrote in message
...

What kind of CRT is this that the wire is soldered on? I've
never seen on
that didn't have a metal cup that the wire just clips into, not
saying they
don't exist, but I've yet to ever come across one.

out of a Tek o-scope

ever since TEK began making their own CRTs with the ceramic bell,they have
affixed the anode lead to the CRT bell.
I've seen maybe one failure of that joint in my 21.5 years
there.Usually,it's because some customer tried to measure the anode V by
digging under the silicone rubber seal.




robb


Personally, I think that at last initially, I would feel inclined to
leave the factory connection to the good CRT alone, and go down the
splicing route. If you do a really nice job of soldering the two wire
tails side by side with a generous 'blob' of solder to make sure that
there are no spikes, you shouldn't have an intitial problem with
corona discharge. When you are happy with the solder joint, use a
piece of insulation sleeve, slit lengthwise, to cover the join.
Before making the soldered joint, slide a couple of lengths of
hetshrink tubing over the lead. When you have your slit tubing in
place over the joint, work a bit of silicon rubber into the slit,
around the joint, then shrink the first piece of tubing over the
whole joint. When that has cooled down, slide the second (slightly
longer) piece over the whole lot.

I have spliced several high voltage wires of various types over the
years, using basically this method, and have never had a problem. And
at least if it doesn't work for you, you've then still got the
damage-riskier option of trying to get a good bond at the actual CRT
connection.


The OP wants to be careful with splicing in a scope. I reckon that any
point in the HV lead that is not contiguous might have the possibility
of generating some RFI which could have consequences when measuring
delicate signals. I'll assume this is also the reason the anode cap is
taped over with copper.



While at TEK,I had to splice a few 634 monitor anode leads,and we used a
silicone rubber tubing to go over the soldered splice,then heatshrink over
that to keep it in place. 10KV or more has a way of finding any pinhole or
leakage path and making arcs,carbonizing a better path,etc.

But I missed the reason WHY the OP wants to splice the CRT anode lead.

--
Jim Yanik
jyanik
at
kua.net