I found some info-Google is your friend BTA-5T: http://www.nrcdxas.org/articles/bta5t/ BTA-5H: http://www.rossrevenge.co.uk/tx/five.htm I was right-I remember this exact transmiutter (I worked at 790 in RI and we ran it as an aux). The 5 kW version has two PA tubes, the 10 kW had three. -D