[Amps] AL-80A tube glow

[Gudguyham at aol.com]

In a message dated 7/7/2007 3:10:01 A.M. Eastern Standard Time,  
kim.ostman at tut.fi writes:

Something that I've paid notice to only as of late in the 3-500Z  tube  
is a gradually increasing orange or light red colored glow in  the  
metallic cooler wings(?) as one sends CW of SSB during an  "over". Is  
it normal for the tube to begin glowing like that, or is  something  
wrong?



A.  Under normal transmitting conditions at 700 to 1000 watts output  it is 
NORMAL for a single 3-500 tube to show such color.  HOWEVER you  mention the 
tube shows color on an "over".  I assume you mean that the amp  is in standby 
mode and not transmitting.  In the stand by mode the tube  should show NO color 
it should be biased to cut off.  IF... there is color  shown at this time, 
there is a problem in the bias circuit and it should be  looked into.  But 
transmitting, the tube may show color and that would be  normal.  Lou



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