tube manual shows 0.15amp required for each tube such as 12be6 etc. how do we convert this to miliamps.? to determine the size of the replacement rectifier to operate a five tube radio.

High math here: 0.15 amps = 150 miliamps.

But you don't need DC on a 12BE6 heater.

Only for plate and screen current.

-Nat

:tube manual shows 0.15amp required for each tube such as 12be6 etc. how do we convert this to miliamps.? to determine the size of the replacement rectifier to operate a five tube radio.

.15 amperes is the amperage rating of the filaments. This rating has absolutely nothing to do with the current used by the tube plates and screen grids. The rectifier of your radio only supplies current to the plates and screen grids. The filaments receive their power directly from the line.

Keep in mind that what I am about to say applies ONLY TO AC-DC RADIOS WITH .15 AMPERE TUBES. Again, .15 refers to the filament current requirements of each tube, not the plate and screen grid requirements.

To determine the current requirements of the rectifier, determine how many strings of tubes are in your radio. Pull out a tube and see which tubes go out. If they all go out, then you have 1 string. If you have a larger AM-FM stereo radio, it may contain two or more strings of tubes. If you pull out a tube and half the tubes go out, but the rest stay lit, then you have two series strings. Pull out one of the remaining lit tubes. If they all go out now, then you can be sure that you have two series strings.

The current rating of one complete series string at 120 volts is .15 amperes. Take the current rating and multiply it by the voltage. .15x120=18 This is the WATTAGE drawn by one series string of tubes. If you have two series strings, multiply this number by 2.

Now take the TOTAL wattage rating of the radio listed on the back cover. Subtract the FILAMENT wattage from the TOTAL wattage. Let's say that the radio is a 30 watt radio. 30-18=12. So, that said, the plates and screen grids of your radio draw 12 watts to operate properly. This is how much your replacement rectifier must handle. To get the amperage rating, divide the wattage by the voltage used (120 volts). 12/120=.1 Your new rectifier must be able to handle .1 amperes. To be safe, make it .12 or .15 amperes so that it is perfectly capable of handling a little extra from surges, etc. To convert this rating to ma., or miliamperes, multiply it by 1,000. This will give you 100 miliamperes, or the safer rating for the new rectifier, of 120 or 150 miliamperes. Be sure that your rectifier has at least a 200 volt forward and reverse rating. This will protect you from line surges.

Now, some day you may run across an AC/DC radio that you like, and it may have the older .3 ampere tubes (usually this radio will have a ballast resistor or line cord resistor of some type). Typically these radios did not have solid state rectifiers, but if you would need the plate current rating for one of these radios, you'd use .3 amperes instead of .15, and multiply this by 120, which would give you the wattage drawn by the filaments of the radio. Then you would subtract this from the total wattage of the radio, which would give you the remaining wattage consumed by the plates and screen grids of the tubes. Continue the process to acquire your ma. current draw by the plates and screen grids, which, as above, will be your requirement for a solid state rectifier.

Solid state rectifiers are sometimes used in AC radios, so knowing how to replace one can come in handy. For an AC radio (with power transformer), the filaments are wired in parallel, and you will have to determine the voltage and amperage of each tube separately by consulting your tube manual. Multiply the voltage and amperage of each tube separately to get the wattage drawn by each filament of each tube. Add these wattages up. Take the total wattage of the filaments subtract this from the total wattage of the radio. The remaining wattage will be your plate and screen grid wattage. Divide this wattage by THE VOLTAGE USED BY THE PLATES AND SCREEN GRIDS. Since AC radios usually use a step-up transformer, this voltage will be higher than 120 volts. It will be somewhere between 200 and 400 volts. Consult your circuit diagram. By dividing the total plate wattage by the power supply voltage, you will get the amperage drawn through the rectifier. Multiply this by 1,000, and you will get the ma. requirements of the replacement rectifier. The forward voltage of your rectifier should be at least 50 volts higher than the voltage put out by your transformer, and reverse voltage should be at least 100 volts more than that put out by the power transformer.

Thomas

:.15 amperes is the amperage rating of the filaments. This rating has absolutely nothing to do with the current used by the tube plates and screen grids. The rectifier of your radio only supplies current to the plates and screen grids. The filaments receive their power directly from the line.
:
:Keep in mind that what I am about to say applies ONLY TO AC-DC RADIOS WITH .15 AMPERE TUBES. Again, .15 refers to the filament current requirements of each tube, not the plate and screen grid requirements.
:
:To determine the current requirements of the rectifier, determine how many strings of tubes are in your radio. Pull out a tube and see which tubes go out. If they all go out, then you have 1 string. If you have a larger AM-FM stereo radio, it may contain two or more strings of tubes. If you pull out a tube and half the tubes go out, but the rest stay lit, then you have two series strings. Pull out one of the remaining lit tubes. If they all go out now, then you can be sure that you have two series strings.
:
:The current rating of one complete series string at 120 volts is .15 amperes. Take the current rating and multiply it by the voltage. .15x120=18 This is the WATTAGE drawn by one series string of tubes. If you have two series strings, multiply this number by 2.
:
:Now take the TOTAL wattage rating of the radio listed on the back cover. Subtract the FILAMENT wattage from the TOTAL wattage. Let's say that the radio is a 30 watt radio. 30-18=12. So, that said, the plates and screen grids of your radio draw 12 watts to operate properly. This is how much your replacement rectifier must handle. To get the amperage rating, divide the wattage by the voltage used (120 volts). 12/120=.1 Your new rectifier must be able to handle .1 amperes. To be safe, make it .12 or .15 amperes so that it is perfectly capable of handling a little extra from surges, etc. To convert this rating to ma., or miliamperes, multiply it by 1,000. This will give you 100 miliamperes, or the safer rating for the new rectifier, of 120 or 150 miliamperes. Be sure that your rectifier has at least a 200 volt forward and reverse rating. This will protect you from line surges.
:
:Now, some day you may run across an AC/DC radio that you like, and it may have the older .3 ampere tubes (usually this radio will have a ballast resistor or line cord resistor of some type). Typically these radios did not have solid state rectifiers, but if you would need the plate current rating for one of these radios, you'd use .3 amperes instead of .15, and multiply this by 120, which would give you the wattage drawn by the filaments of the radio. Then you would subtract this from the total wattage of the radio, which would give you the remaining wattage consumed by the plates and screen grids of the tubes. Continue the process to acquire your ma. current draw by the plates and screen grids, which, as above, will be your requirement for a solid state rectifier.
:
:Solid state rectifiers are sometimes used in AC radios, so knowing how to replace one can come in handy. For an AC radio (with power transformer), the filaments are wired in parallel, and you will have to determine the voltage and amperage of each tube separately by consulting your tube manual. Multiply the voltage and amperage of each tube separately to get the wattage drawn by each filament of each tube. Add these wattages up. Take the total wattage of the filaments subtract this from the total wattage of the radio. The remaining wattage will be your plate and screen grid wattage. Divide this wattage by THE VOLTAGE USED BY THE PLATES AND SCREEN GRIDS. Since AC radios usually use a step-up transformer, this voltage will be higher than 120 volts. It will be somewhere between 200 and 400 volts. Consult your circuit diagram. By dividing the total plate wattage by the power supply voltage, you will get the amperage drawn through the rectifier. Multiply this by 1,000, and you will get the ma. requirements of the replacement rectifier. The forward voltage of your rectifier should be at least 50 volts higher than the voltage put out by your transformer, and reverse voltage should be at least 100 volts more than that put out by the power transformer.
:
:Thomas