[Amps] Passive grid triodes?

[TexasRF@aol.com]

Bill, this is a wild guess on my part and assuming a linear class of  
operation:
 
Bias voltage for triodes is much lower typically than a similar power  
tetrode. To achieve a decent power output level, there is going to be quite a  bit 
of grid current. As Rich has pointed out many times, grid current is usually  
accompanied by rf "feculence".
 
On the other hand, grounded grid operation automatically provides a large  
amount of negative feedback that will mitigate the "feculence" to a large  
degree.
 
When a typical tetrode is operated in a passive circuit, there is usually  
zero grid current and the "feculence" is avoided.
 
Tetrodes operated as grounded grid will benefit from the negative feedback  
and grid current can be drawn as a result.
 
Grid current is related to rf drive power and plate current is increased in  
the process. Higher plate current will generate more power output. More output 
 power is nice only if the signal stays clean. Grounded grid operation helps 
with  this because of the negative feedback.
 
73,
Gerald K5GW
 
 
 
 
 
In a message dated 2/17/2006 12:35:52 P.M. Central Standard Time,  
dezrat1242 at ispwest.com writes:

I don't  recall seeing any passive grid triode circuits and I'm 
wondering why. They  always seem to be tetrodes. Is it a neutralization issue?

73, Bill  W6WRT

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