On 5/2/2012 1:40 PM, Charles Harpole wrote:
> Has anyone on Planet Earth ever heard of copper or tined copper "becoming
> brittle" due to heat?
If you overheat copper you are getting it way too hot. and probably
damaging the dielectric as well.
Overheated copper becomes soft.
Today's popular cables uses braid plus foil and that braid is extremely
fine wire that is quite fragile.
That's how they keep them at a reasonable price.
>
>
>
> And what about the report of not soldering the center conductor because of
> the use of high power and 70 ohm coax?
The only problem I can see about soldering and high power would be if
the solder job were sloppy, or the connectors did not mate well and
would overheat from the high resistance connection. All connectors I
use on 70 ohm coax have a soldered center pin. Of course if they are
talking about CATV line or flexible CATV line that uses an Aluminum
shield that has to be either clamp or crimp. I use 1/2 tube couplings,
or 3/4" modified couplings to grip a conventional coax fitting barrel.
On LMR-400 I use, both Clamp and crimp connectors. In both UHF and N
connectors I solder the center connector. LMR-400UF fits most UHF
connectors although it may be a very tight fit in some. If necessary I
tighten the twist of the wires in the center conductor and *carefully*
twist the connector on.
For those who have problems with them, you can tin the center conductor,
bonding those wires together. You may need to use a file or emery board
to carefully trim the size after tinning but it's normally a lot of
unnecessary work. Many of the UHF connectors have the center pin swedged
down to a smaller diameter at the tip for crimping. I still solder the
center pin after crimping.
With N connectors they appear to have less clearance and I have blown a
number of them out when operating the legal limit on 75 and 160 well
away from resonance.
An important thing to remember about N connectors is the center pin is
not captive on most of them. If the coax is vertical, say running from a
connector at the to to one at the bottom the weight will *often* cause
the center to migrate down, causing the top connector's center pin to
either lose connection, or become a relatively high resistance. On 100
foot plus vertical runs it is critical that the bottom connector's
center pin extend out tot he point when the shoulder rests on the next
connector's shoulder to minimize the capability for the center conductor
to migrate. OTOH on long runs that may not be enough to prevent enough
migration to cause problems. They really should make the N connector
with a captive center pin that can be disassembled for soldering the
center pin Yes I have had type N crimp connectors come apart on LMR-400
where there was a bend close to the connector. I have never had one
come apart on LMR-600.
I have a bulkhead (1 1/2" Aluminum angle with bulkhead connectors. I
come off the connector with a single coil loop that also forms a drip
loop and it reaches the tower leg *above* the bulkhead. At that point
the coax is tapped to the tower leg. I don't like the extra length and
loop in the grounding system, but I've not had any center conductor
migration in those instances. I prefer to use compression, or clamp
type UHF connectors in these cases.
With LMR-600 I use both crimp type N or clamp type UHF with soldered
center pins.
73
Roger (K8RI)
>
>
> Was I naping when some passed the ham test? 73,
>
>
>
> Charles Harpole
> k4vud@hotmail.com
>
>
> ----------------------------------------
>> Date: Wed, 2 May 2012 10:12:37 -0700
>> From: k2vco.vic@gmail.com
>> To: amps@contesting.com
>> Subject: Re: [Amps] soldering vs crimping
>>
>> It's not tricky if you have three things:
>>
>> 1) The right soldering iron. I have a Weller W100P that I use for this. It's
>> also handy
>> for copper tubing and strap in tank circuits, etc. It has a large thermal
>> mass so that the
>> heat is transferred to the connector quickly, and is also temperature
>> controlled.
>>
>> 2) Decent connectors. You need these anyway! I have some that I inherited
>> that solder
>> doesn't stick to.
>>
>> 3) Decent coax, with good braid coverage. Again, you need this anyway.
>>
>> On 5/2/2012 9:51 AM, Dick Green WC1M wrote:
>>> I'm with Carl on this one. Actually, the crimp N-connectors I use have
>>> center pins designed to be crimped *and* soldered -- there's a little hole
>>> in the side for soldering. I've found that there's so much variation in
>>> center conductor size that crimping *and* soldering makes for the most
>>> secure connection. The UHF crimp connectors I use all require soldering for
>>> the center conductor -- you can't crimp it. As for the shield, there's no
>>> question in my mind that crimping is superior to soldering. It's very
>>> difficult to properly solder shield braid without overheating it and melting
>>> the dielectric. I'm not saying it can't be done -- only that it's tricky.
>>> I've only had a few solder connector failures over the years, but they've
>>> all involved either deformation of the dielectric due to overheating, or
>>> breaking of the shield because it became brittle after soldering.
>>>
>>> 73, Dick WC1M
>>
>> --
>> Vic, K2VCO
>> Fresno CA
>> http://www.qsl.net/k2vco/
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