Sorry, the PA0FRI amp project used GU-43b, but am sure would translate to Gu-84 etc. The web address: www.pa0fri.geerligs.com The Gu-43 project seems an excellent place to go for ideas on a reasonably high powered HF amp. There is also much else of interest on the site. 73 Barry ZL1DD -- Barry Kirkwood PhD ZL1DD barry.kirkwood at gmail.com