All replicators should pay attention to Rossi's provisional US-patent 61/999,582, filing-date: August 01, 2014. Provisional patents are not published at USPTO but another site published a copy of this patent which contains the following description:
"In a reactor are put nickel powders, hydrides at a pressure of 3-6 bars an a temperature of 400-600 Celsius, AND AT ONE SIDE OF THE REACTOR IS PUT AN ANODE, AT THE OPPOSITE A CATHODE, so that electrons are accelerated up to 100 keV, ..."
At the ends of the reactor are an anode and a cathode!!!
"4 - a generator of direct current connected with a cathode and an anode to accelrate the electrons"
So Rossi is using DC to initiate (and maybe control) the reaction. (And possibly uses the anode and cathode for direct extraction of electric energy after the reaction occured - ECatX.)
Available text/description from 61/999,582:
My speculation ist that Rossi has allways used DC to trigger (and control) the reaction in his working samples but never disclosed this fact. This makes perfect sense because describing this in a patent which is normally not public availiable gives him "prior art" and his published patents e.g. US 9,115,913 B1, WO2016018851 A1 which contain no reference to the anode/cathode and dc usage, can conceal this fact but claiming priotry of 61/999,582.
Another speculation is that 61/999,582 shows the conception of his E-CatX.
And maybe both speculations are true.