Just a quick word about the 4CX350.
350 is bigger than 250, so it must be better, right?
Not in this case. The 350 is built to work with far less drive than the 250. The input side of the 250, the control grid will tolerate 2 Watts of drive, more or less. The Pride's input circuit only lets the tube have about 15 or 20 percent of the radio's power. A couple of resistors handle the rest of it.
Still, the grid rating on the 350 is ZERO Watts.
Sounds wrong. How do you drive a tube with zero Watts?
It's about using only voltage to drive the tube. Power is current times voltage. When the current is equal to zero, won't matter how high the voltage is. Power is still zero. If the drive power stays below a limit where the tube's grid does not draw any current, only the rest of the circuit's components draw current and dissipate heat from the input power. The tube's grid only draws current from the driver when the drive level reaches this threshold. But this tube's drive must be kept below that threshold. The '250 is a lot more forgiving about this 'current' limit.
The 350 nearly always dies a tragic death in a Pride. It has nothing built in to show you when the danger limit of the drive power is reached.
Now and again you hear from someone who stayed below that limit and got good service from this type tube. You can be sure that the drive power somehow remained below the "red line".
But there is no reliable way to hold your drive power below that line. No red line to watch out for.
But for someone who thought "a little more" power would be a good thing, this tube just sounds like you'll get more from it.
But not for long.
73
350 is bigger than 250, so it must be better, right?
Not in this case. The 350 is built to work with far less drive than the 250. The input side of the 250, the control grid will tolerate 2 Watts of drive, more or less. The Pride's input circuit only lets the tube have about 15 or 20 percent of the radio's power. A couple of resistors handle the rest of it.
Still, the grid rating on the 350 is ZERO Watts.
Sounds wrong. How do you drive a tube with zero Watts?
It's about using only voltage to drive the tube. Power is current times voltage. When the current is equal to zero, won't matter how high the voltage is. Power is still zero. If the drive power stays below a limit where the tube's grid does not draw any current, only the rest of the circuit's components draw current and dissipate heat from the input power. The tube's grid only draws current from the driver when the drive level reaches this threshold. But this tube's drive must be kept below that threshold. The '250 is a lot more forgiving about this 'current' limit.
The 350 nearly always dies a tragic death in a Pride. It has nothing built in to show you when the danger limit of the drive power is reached.
Now and again you hear from someone who stayed below that limit and got good service from this type tube. You can be sure that the drive power somehow remained below the "red line".
But there is no reliable way to hold your drive power below that line. No red line to watch out for.
But for someone who thought "a little more" power would be a good thing, this tube just sounds like you'll get more from it.
But not for long.
73
