http://www.lincolnelectric.com/assets/servicenavigator-public/lincoln3/im298.pdf

A rather popular unit to this day. By itself with no peddle or torch maybe $150-200 tops for me if looking for one. Very applicable to any Idealarc CC machine.

 

Ok great. I'm going to contact the seller and have a look at it. I did see a completed auction on ebay for twice what the seller is asking for this unit so thats comforting.

 

I've been reading about this Hi_Freq unit but can't tell if the pedal will adjust the heat or if its just for starting the arc.
The pedal connects to the Arc Spark Start Receptacle. I can't find anything about the pedal in the pdf except that it is an accessory.
Any ideas?

 

just a HF start switch. The welder output must already be turned on.
Take the code number off the front panel and go to lincoln's web site.
With the code number you can down load the correct owners manual for your machine.
To control the welder on and off and up/ down. You will have to add it, with HF isolation.
I am thinking this unit was designed for use with engine drive welders. Or any stick welder.
Owners manual shows a voltage range that this unit operates in. May not work with low OCV welders.

 

While that would make it possible to weld alum, chances are you won't be happy with the result. With no pedal to control you amps ( pedal only initiates the arc) it will be tough to control your heat. I'm not saying it can't be done, only that it takes a much higher level of skill to pull this off successfully. You'd really be better off with a dedicated AC/DC tig.