[TenTec] Herc II and 9420 duty cycle

[Ken Brown]

Hi Phil,

Thanks for the suggestion.

I see how the currents to the four PA modules is monitored by the 
voltage drop across the 0.015 ohm resistors on the DC Distribution 
Board, and then combined together to feed the Ic meter. And I see the 
individual bias adjust pots on the Bias Board. I do not see a convenient 
way to measure the PA module current for each PA module individually. 
Perhaps I could just put my DMM across the 0.015 ohm resistors one at a 
time. Or I could arrange to actuate K1, K2, K3 or K4 individually, one 
at a time and use the Hercules Ic meter.

My manual does not state what the idling collector current ought to be, 
either for each PA module or the total, and there is no procedure 
described for adjusting the bias. The Ic meter shows about 12 or 13 
Amperes (half way to the 25 A hash mark) idling collector current.

I suppose I could measure the voltage drop across across the 0.015 ohm 
resistors, and then adjust the appropriate bias pot until whichever 
current is highest is brought down to be equal to the lowest, or maybe 
the average. I'd rather know what it is supposed to be first. Does 
anyone know the specification the Hecules II idling collector current, 
either total or for each individual PA module?

Ken N6KB




Phil Chambley, Sr. wrote:

>I think it would be a good idea to check the idling collector current on the
>finals.
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