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Mon, 7 Mar 2011 16:32:55 -0700 |
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I reflect the sentiment that, no, it isn't usually a good idea to splice
coax unless you absolutely have to do it to get back on the air.
If you do have to splice it, there are a few ways to do it so that it
reduces the bump which will cause the coax to be off the 50Ohm capacitance
rating at that point...when a coax doesn't have a consistance spacing
between the center conducter and the shield, the rating alters which leads
to standing waves at that point along the coax...heat, and other nasties.
You need to splice the coax in a way that makes it as close to the original
spacing and original diameter etc.
I've been known to use tin foil to make the shield continuous in a splice.
Of course the problem there is that you run into problems using different
metals...changing from copper to alluminum back to copper...it introduces
resistance into the coax that wasn't there before.
One of the ways i've done it is to feed the multi-strand center conducter
together so that it is the same size as the rest of the center conducter,
Solder that connection point, then use small heat shrink tubing to seal and
insulate the center conducter at the bear connection point...then slide the
shield back over the heat shrink tubing until it's touching...drip solder
over as much of that connection as possible, then wrap the beared portion of
the shield with alluminum foil...then use the appropriate sized heat shrink
tubing on the outside to seal and insulate the shield as well.
This takes some pre thought and you have to cut the ends of the two pieces
of coax so that you have enough of the shield to pull back over the center
splice and electrically connect them together...also you need to cut the
right lengths of heat shrink tubing to slip over the coax before you splice
it.
You can use electrical tape instead of heat shrink tubing as well...but it
won't last as long.
Though electrical tape has a better insulating factor, several KV per layer
I think...so it would work better as a dialectric than heat shrink tubing
might.
best to go and buy a new chunk of coax with or without the ends you need in
this situation.
Especially if you are trying to splice RG58 type coax...that stuff is allot
harder to splice than say RG8 style or 213, or 9913, or LMR 400 etc.
73
Colin, V A6BKX
----- Original Message -----
From: "Christopher Moore" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, March 07, 2011 2:27 PM
Subject: splicing coax
> Hello,
> Is it a good idea to splice coax? I wouldn't consider it for an outdoor
> run but what about indoors?
>
> Chris
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