[TowerTalk] Slobering Irons

[Richard (Rick) Karlquist]

On 7/28/2015 2:24 AM, Bryan Fields wrote:
> On 7/26/15 8:55 PM, Roger (K8RI) on TT wrote:
>> I use a soldering station.  I think it's a Weller, but it's in the shop
>> and I'm in the house.  It's a rarger simple affair, with a coil holder
>> for the iron and adjustable heat.  It has a small tray to hold a sponge
>> with water for wiping the tip.  The tips screw in.  I don't like the
>> cheap ones that use a set screw to hold the tips.
>
> TBQH the weller stations are crap.  I had one and loved it, until I was
> introduced to a Metcal soldering station.

Exactly my opinion too.

>
> The metcal uses a 13.65 MHz RF source to heat the tip of the iron up, and once
> it hits the set point, the tuned circuit changes in the tip and it stops
> heating. As soon as it cools, it begins heating back to the set point.  This
> makes a 40w iron act like a much larger conventional heating element iron.

Not quite, it's even better than that.  There is no tuned circuit, but
instead the tip metal reaches its Curie temperature and becomes
non-magnetic.  Non-magnetic metals have much lower RF losses and
therefore the tip heating is greatly reduced above the set point.
The regulation of temperature is on an atom by atom basis.

Interestingly, the Weller also uses the Curie effect, but only to
switch the electric current on and off.  Much less effective.

> What's interesting with the metcal is there is no adjustment for the
> temperature, the tip has a set temperature and will stay at it.

There is no adjustment per se, but the tips come in various set point
temperatures, just like Weller.

> I have a magnetic holder that the iron rests in, the magnetic field de-tunes
> the tip so it cools down to 300f from 700f, prolonging the tip life.  When
> it's removed, the tip heats up in under a second.  Even from power off the tip
> is up to working temp in under 2 seconds.

That's very interesting.  I have never heard of it in 30 years of using
Metcal's.  Can you tell us where to buy it?  Thanks.

Rick N6RK