[Heath] SB-102 Idling plate current

[James Owen]

Hi Joe,    I think you have gassy tubes.  I have had this in the past with gassy ones in which over a couple minute of an SSB transmission the current would go from 50ma to over 200ma. Even NOS tubes will usually have this problem as the elements out-gas and the getter requires high temperature to work.  I bet if you left the transceiver on for 24 hours the problem would go away.  It would even help if you could get the tubes a little hotter than filaments alone would do by putting it in transmit with no carrier or audio just the 50ma bias current.  Turn mic gain to zero and also carrier and lock down the push to talk.  Watch it frequently during the first hour to be sure it doesn't rise too high, not over 100ma, and if it does reduce a little by resetting the bias.  BTW do you know where I can get a pair of 6146B's or 6146W's without paying an arm and leg. 

73 Jim K4CGY
 James C. Owen, III K4CGY

      From: Joseph Smalley via Heath <heath at puck.nether.net>
 To: "heath at puck.nether.net" <heath at puck.nether.net> 
 Sent: Monday, February 22, 2016 9:05 PM
 Subject: [Heath] SB-102 Idling plate current
   
Hello fellow Hams, Name is Joe, call WA3CKA, builder of my SB-102 in 1972, updated 3 years ago in use everyday.
I find that the idling plate current rises above the 50 ma setting as I transmit in a normal length CW QSO maybe 5 minutes.  

Final tubes were new old stock now 3 years old.  Any suggestions as what may be causing this condition.
You can speak to me in technical terms if you want as I am a retired electronics tech.  So far I find nothing wrong.
I only do CW.  73 to all.
Joe WA3CKA



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