Hi guys,

Could you tell me what sort of wattage a soldering iron needs to have
to cope with soldering co-ax into PL509s?

The PL509 is a vacuum tube... I assume you mean a PL-259 "UHF" connector?

They need a good deal of heat delivered, due to the large metal mass.
A small iron will heat the connector slowly... by the time you manage
to make a solder bond, the cable itself will have been heated up a lot
and there can be problems with the dielectric melting. An iron with
higher wattage (and/or lots of mass, well heated) can make a quicker
job of it and let you make the solder joint more quickly.

I've had the best luck with a full-sized Weller soldering iron (the
140/200 watt variety). I think I recall doing one or two with a
Weller WTCP iron using a large tip, but it wasn't easy. Butane-fired
portable soldering irons are another possibility... some of these can
deliver a lot of heat.

Another possibility is to hold the connector and cable in place with a
clamping arrangement somehow, pre-heat the connector with a hot-air
gun (a hair dryer will do) and then finish the job with a
smaller-wattage soldering iron. By preheating the connector you
reduce its tendency to sink heat away from area that you're trying to
solder.

There are some alternative PL-259 connectors, which use a crimper and
a proper die set rather than soldering. See the discussion at
http://www.eham.net/articles/19257 for a look-see. A properly-done
crimp can be just as permanent as a solder junction... sometimes
better.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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