[Heath] SB-102 Idling plate current

[Glen Zook]

Have you replaced the 6-each 10-ohm resistors that go from pins 1, 4, and 6 of the final amplifier tubes to ground?  If not, replace them with modern 1-watt resistors which are about the same size as the original 1/2-watt resistors.  These resistors actually form the meter shunt when the meter is in the "plate" position since the "plate" meter actually reads cathode current.  The original cathode resistors change value over the years and cause all sorts of "plate" meter problems.


A little rise in the "plate" current reading is common.  But a lot of rise is not!

 Glen, K9STH 
Website: http://k9sth.net

      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 8:05 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.

  
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