[Hallicrafters] HT-37 Bias

[wb8jkr at juno.com]

 They don't, that would be class A operation. The
bias voltage should be about -49 volts and I'm 
guessing the plate idle current is probably around
50-70 ma. for the pair of tubes.
 They simply mean they are using the full capability
of the 6146 when driven to maximum output.

Mark  WB8JKR


On Wed, 18 Aug 2004 19:43:25 +0600 Bill <k2wh at optonline.net> writes:
> Can someone tell me why the finals in the HT-37 are apparently run
> 100% of the time at full plate dissipation?  This condition occurs 
> even
> during
> receive and standby periods.  The manual for the HT-37 under the 
> BIAS
> section,
> states “the final amplifier tubes are operated close to rated plate
> dissipation for optimum performance”.
>  
> Does this mean all the time or just during transmit?  It would seem 
> to
> me
> that a simple circuit mod to increase the bias to a higher level 
> during
> receive
> or standby periods would allow these tubes to cool down.  Then again
> Hallicrafters may want to tubes hot to allow the rig to stay warm 
> and
> stabilize  and also to stop heat cycling of the finals limiting
> mechanical
> stresses on the tubes.
>  
> Anyone have any ideas on why this is the way it is?  I’m inclined to 
> add
> a simple circuit to increase the BIAS on these tubes during receive 
> or
> standby to cut down on the heat.
>  
> K2WH
>  
>

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