About new RT tips

A project log for RT Soldering pen

Soldering pen for Weller RT tips with OLED display

vlkvlk 12/08/2019 at 18:550 Comments

RTM, RTP and RTU tips

Weller this year introduced new series of RT tips with nice slogan "No compromise".

There are three types:

All the tips have same pinout and in general are compatible,

RTM and RTP (also previous RT) have resistance of heating element 2 Ohm and they are designed for 12 V (current is 6 A) but maximum average heating power is 40 Watts - this power is controlled and limited by PWM.

RTU has resistance of heating element 3.5 Ohm, this mean, to reach 150Watts is necessary to use higher voltage - at least 24V, but the current will be still similar - what is good for the JACK connector.

But actual design of RT soldering pen has limitation for power at 18 V and current to RT, RTM and RTP will be at 18 V: 9 Amps - the pen it should withstand it, because average pulse power is limited by SW to 40 W) question is what can withstand the JACK connector.

The main question is how to use this with RTU tips they need 24 V. so, absolute maximum rating of HW 1.0* is 25V for supply voltage (limiting element is input capacitor) after replacing input cap next limit will be 30V (maximum voltage of MOSFET switches)

*Absolute maximum rating for previous HW v0.3 is 20V - this is limited by 20V MOSFET switch.

For RTU if the supply will be 24V then output power can be near to 150 Watts, but this need also modifications in SW to allow higher output power. Yes, this is planed and new release will available be soon.

Another problem with new tips is that each kind RT/RTM, RTP and RTU has different dimensions of the cylinder on JACK side and is necessary to count with this for case design. (old RT and new RTM have same dimensions of the cylinder) this is also reason why Weller sell for each kind different tip holder.

MS tips:

If I talking about tips there is one more question: What it mean if in name is "MS", it mean that tip meets Military Specifications. But there is no more informations. In general the main different is that shield of the tip is electrically isolated from the connector, standard tips have shield connected to ground.

Weller RT TIP typemax average powerheater element resistancecurrent  and power at 12Vcurrent and power at 16Vcurrent and power at 24V
RTM / RT40W (55W*)6A / 72W8A / 128W-
40W6A / 72W8A / 128W-
RTU150W3.5Ω3.4A / 41W4.6A / 73W6.8A / 164W

* some RT tips have 55W limit (RTM 36 S / RT 11)

from left: RTP, RTM, RTM MS, RTU