[Amps] Yeasu 2100B

[loaks2@comcast.net]

I have a Yeasu 2100B amp that has a problem on 40 meters.  The load control is at the end of the range on 40 and I am experiencing lower output than the other bands with the same drive and plate current.  The amp is new to me and I expect the lower loading is related to using Svetlana 572Bs.  These tubes are fairly new and came with the amp.  However,  80,20,15,10 react as I would expect as to output and plate current.   All voltages are fine and the mod to increase cutoff voltage for the Svetlana has been done.  The band switches look fine and the plate tuning is correct and in the ranges you would expect as per Yeasu.   In all other aspects the amp works fine.  I have had a parasitic event recently that resulted in burned resistors and a shorted grid bypass cap.   The load issue predated the EVENT.  Anyone seen anything like this related to Svetlana tubes or the 2100B???    

Larry
WB9YAJ 


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