And, I was trying to keep it simply for the "Masses", I would order a transformer that supplied 1800 VAC at 1.0 amps. When rectified with a FWB, you will have plenty of volts for the anodes of those tubes and you will still be within the safety range.
There was another discussion about trying to make this amplifier variable by moving the bias pot to the front and allowing the user to "adjust" his output by jacking off the negative-going voltage on the control grid; this is a bad idea.
The bias is used to set the idle current on those tube, you should not screw with that after it is set or you will be buying tubes sooner than you think.
Ceramic tubes are not the same as the glass 6lq6 so, you don't go jerking with the bias like you did in sweep-tube amps.
The operating dynamics of a tube running 2400 volts on the plate, 400 volts on the screen, and -60 volts on the control grid will totally be screwed up when you lower the bias voltage.
The proper way to adjust the power output of a 4cx250 tube is to lower or raise the voltage on the screen grid. This can be done by placing zener diodes in series to control the level of the screen volts and the taping into the various amounts of voltage at different points along the string of zeners; a rotary switch supplying 100 volts, 200, volts, 300 volts etc to the screen grid would raise and lower the output of the tube.
BTW, somebody told you guys that if you lower your carrier you will sound louder, you probably will but, it takes more that 1 watt to effectively tune and operate a RF amplifier in a linear mode while transmitting AM.
.
There was another discussion about trying to make this amplifier variable by moving the bias pot to the front and allowing the user to "adjust" his output by jacking off the negative-going voltage on the control grid; this is a bad idea.
The bias is used to set the idle current on those tube, you should not screw with that after it is set or you will be buying tubes sooner than you think.
Ceramic tubes are not the same as the glass 6lq6 so, you don't go jerking with the bias like you did in sweep-tube amps.
The operating dynamics of a tube running 2400 volts on the plate, 400 volts on the screen, and -60 volts on the control grid will totally be screwed up when you lower the bias voltage.
The proper way to adjust the power output of a 4cx250 tube is to lower or raise the voltage on the screen grid. This can be done by placing zener diodes in series to control the level of the screen volts and the taping into the various amounts of voltage at different points along the string of zeners; a rotary switch supplying 100 volts, 200, volts, 300 volts etc to the screen grid would raise and lower the output of the tube.
BTW, somebody told you guys that if you lower your carrier you will sound louder, you probably will but, it takes more that 1 watt to effectively tune and operate a RF amplifier in a linear mode while transmitting AM.
.
