[Amps] Changing class of operation with BIAS

[donroden at hiwaay.net]

And in broadcast applications, I have always preferred to run higher  
plate voltage and less plate current for a given output wattage for  
longer tube life. ( tubes with handles )

Don W4DNR



Quoting Rob Atkinson <ranchorobbo at gmail.com>:

>> So you are not changing the bias, even though resting current has  
>> changed, but
>> you are changing the conduction angle and thus the class of  
>> operation (triode).
>> Question: How can you change the class of operation and conduction  
>> angle with
>> no change to bias. I apologize, but I am confused.
>
> You got a lot of answers, a lot of words, some or all correct, but not
> what I think you were looking for.
>
> A tube (triode for example) is like a ball valve in a water pipe.  You
> can change the flow by cutting it almost off with the valve, but you
> can increase the flow by increasing the pressure into it or the
> suction pulling water out of it.  A tube (called a "valve" in Britain
> not coincidentally) has all kinds of ways of changing its behavior
> besides bias.  Increasing the plate v. alone is like increasing the
> suction on the water coming out of the valve.  Higher positive v.
> exerts an even stronger attractive force on the negatively charged
> electrons boiling off the cathode, in spite of the grid v.   This
> pulls more of them to the anode past the grid and the anode to cathode
> current increases.
>
> 73
> Rob
> K5UJ
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