[Hallicrafters] HT-37 Bias

[wb8jkr at juno.com]

  Any change in R19's value wouldn't change the 
bias voltage to any real degree, there is no current
path to create voltage drop in R19 except for
grid current which would only be a few ma at the most.
 If you've got -49 volts at the grid and the finals idle
between about 40-60 ma with no RF drive, I'd say
nothing is wrong.

Mark  WB8JKR


On Thu, 19 Aug 2004 14:16:44 -0400 k2wh at optonline.net writes:
> I plan on checking the bias voltage at the test point AGAIN, but I 
> know it is -49vdc.  I have check this numerous times and it is 
> always within a volt of -49vdc.  However, looking at the 37 
> schematic, I noticed resistor R19, 1000 ohms in series with both 
> grids.  It is possible this resistor is no longer 1K but has moved 
> higher thereby increasing voltage drop across it and forcing the -49 
> at the tube socket to some other low value.
> 
> Anyway, I plan on checking the bias voltage at the supply test 
> point, check R19, check bias voltage at the tube socket and also 
> lift the plate voltage lead and measure the idling current.  These 
> measurements should once and for all establish what is going on here 
> if anything.  My instincts lead me to R19 as either bad or changed 
> in value or, nothing is wrong at all and the rig is operating 
> normally.
> 
> K2WH
> 
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