I believe the point of having the transformers in their circuit is to limit the maximum output.
A transformer (ferrite in this case) can only output whatever maximum current determined by the core saturation level. They are relying on this property of the transformers to limit the current into the clipping diodes. I believe it was ICE that came up with this technique sometime way back. The diodes set the voltage level of clipping and the transformers limit the maximum current or power into the diodes. The combination realizes a somewhat soft clipping level with a fixed maximum output. Common mode isolation comes for free along with the design. Lee K7TJR _________________ Topband Reflector Archives - http://www.contesting.com/_topband
