My Wellers are the models WP-40 and WP-25. My 'screwdriver tip' on the
WP-25 is probably 1/32 across the rounded tip.
I like Weller soldering irons too. There are so many kinds (of any
brand) that it is important to pay attention to details. It is not just
the power rating of the iron that matters, it is the temperature
control. For desoldering RF power transistors from the printed circuit
board you want the thermal mass and heater power rating of the larger
irons. Say around 25 watts or more. You do not want that heating power
uncontrolled though. Any iron with sufficient power rating for this job,
without temperature control, can get to much higher temperatures than
you want to subject your PCB to. If you use a lower power rated
non-temperature controlled iron, to keep the temperature from getting
too high, then it will not have enough heat capacity to do the job.
If you don't have the power, you'll have to mess with it longer and
damage stuff. If you have the power and too high temperature you'll
damage stuff quickly.
Weller (and others) make irons with magnetic thermal switches in the tip
assembly, that switch the heater on and off to maintain a fairly
constant temperature. That or some other temperature controlled iron is
what you want. You do not want an iron that is just always on. Yes you
could be successful with one of these, using a Variac or SCR control. I
don't recommend it. Temperatur controlled irons cost less than many RF
power transistors, and less than the trouble of replacing a damaged PCB.
Plus they have applications for many other jobs.
DE N6KB
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