Primary Injection test set retrofit

I recently acquired multiple CB-225 PI sets. They all still have the original controls and timers. I am looking to see how difficult it would be to retrofit mac-21…or if it is even possible. There is very little info out there about this retrofit. Any suggestions on where to start would be helpful. TIA

I have done this retrofit with a MAC-20, as well as a MAC-21, in the past. Unfortunately, in my experience, ETI does not sell the retrofit kits for people to install themselves any longer.

Have you already reached out to ETI? The MAC-21 is a solid option to bring those CB-225’s up to date.