"Meat Plow" wrote in message
...
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

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.


The only way that I can see it generating any RFI, is if the joint is not
good enough to be corona-free. Based on what Jim says at the bottom of the
thread, removing the lead from the actual CRT does not seem to be the 'done
thing' - so I'm guessing that there must be a reason for that. Based on that
assumption, I would still think that it was better to at least try to do a
good job on a splice initially, rather than risk 'doing a job' on the new
CRT that left it useless. I would have thought that there is just as much
potential to do a joint at the CRT end that corona'd and generated RFI as
there is of having the same happen at a splice - yes ?

Arfa