Battery Radio Tubes 25 June 2009 Mike at MDBVentures.com Visit us at http://www.MDBVentures.com - Great prices on great tubes! What makes battery radio tubes different from other tubes? The obvious answer is that they are intended for battery operated devices. The most common being portable radios. Being used in a portable battery operated device means that efficiency is a high priority for battery operated tubes. Regular tubes are normally optimized for performance, long life, and low cost. Generally efficency is way down on the list of requirements for regular tubes. The biggest area of change is the heater voltage and current. The battery tube heaters are normally designed to operate on one or two D cell sized batteries (referred to as the "A" battery). This means a heater voltage of 1.4V or 2.8V. The heaters can normally operate well over the range of 1.2V to 1.6V which is the functional range of the typical D cell battery. Tubes designed for battery operation normally have heater currents that are significantly less than regular tubes. Typically around 50 milliamps (compared to 6 volts at 300 milliamps or more for a typical regular tube). With the power output tubes drawing twice that at 100 milliamps. Some tubes have heater currents as low as 20 milliamps at 1.4V. The lower current drastically reduces the drain on the battery. The trade-off is that normally the battery tubes cannot handle very much plate current because of the reduced available electrons being boiled off of the cathode due to the lower filament power. Most battery tubes also operate on low plate voltages. This is not a problem though because high voltage "B" batteries become very expensive as the voltage goes up. The most common B battery voltage is 48V or 67V volts. Although 22V and 90V were used in some applications. The B batteries were rather large because they are actually made up of many smaller battery cells. Carbon/Magnesium was the most common configuration of the B batteries. This is the same chemical make up used in the lower cost carbon based 9V batteries today. They have a long self life that can last for years, but the current draw available is lower than other technologies. But for radio use, the low current is perfectly fine. Since efficency is an important factor and since the tubes are being run from battery, they pretty much all have direct heated cathodes. This means that the heater itself is the cathode. This makes the circuit design a little bit more difficult, but also means a significant lower power requirement to boil the electrons off the cathode. It also has a nice side effect of being "instant on". Indirectly heated cathode take a long time to heat up the cathode before the tube starts to work (15 to 30 seconds typically). Direct heated cathodes of the sort used in battery tubes start to function in less than a second. Some designs even made use of the fast response time of the direct heated cathodes by using it as a part of an automatic volume control circuit. Although that also points out a negative aspect of the direct heated cathode, it is more sensitive to the applied heater voltage than an indirectly heated cathode. Some of the early radio designs had a separate control for the heater voltage to deal with the problem. Battery tubes can be found in all the major tube types, preoctal, octal, miniature and subminature tubes. The largest number of available tubes are in the octal and minature tubes since these were used extensively in portable radios. When considering a tube project that will be operated from batteries, a battery radio tube should be the first tube type to consider using. If you have lots of portable power available (such as in a car), consider looking at a space charge tube. Space charge tubes draw heavy on heater current, but only need 12 volts for plate operation thus eliminating the need for an additional high voltage plate power supply. For more information on space charge tube see http://www.MDBVentures.com/files/spacecharge.txt A listing of space charge tubes can be found here http://www.MDBVentures.com/sctubes/sctubes.htm Below are listed the common battery radio tubes. Not all tubes are listed as there are some special subminature tubes that are not normally listed. Battery Radio Tubes 00A, 5.0V, 0.25A, Triode, Preoctal (4 pin) 01A, 5.0V, 0.25A, Triode, Preoctal (4 pin) 1A4, 2.0V, 0.06A, RF Pentode, Octal 1A5, 1.4V, 0.05A, AF Pentode (100mW), Octal, 1A6, 2.0V, 0.06A, Pentagrid converter, Octal 1A7, 1.4V, 0.05A, Pentagrid converter, Octal 1AC5, 1.25V, 0.04A, AF Pentode (15mW), subminature 1AD4, 1.25V, 0.1A, RF/AF Pentode, subminature 1AD5, 1.25V. 0.04A, RF Pentode, subminature 1AE4, 1.25V, 0.1A, RF Pentode, minature 1AE5, 1.25V, 0.06A, Heptode Mixer, subminature 1AF4, 1.4V, 0.025A Pentode, minature 1AF5, 1.4V, 0.025A Diode/Pentode, minature 1AG4, 1.25V, 0.04A Pentode, subminature 1AG5, 1.25V, 0.04A Diode/Pentode, subminature 1AH4, 1.25V, 0.04A, RF Pentode, subminiature 1AJ5, 1.25V, 0.04A, Diode/Pentode, subminiature 1AK4, 1.25V, 0.02A, RF Pentode, subminiature 1AK5, 1.25V, 0.02A, Diode/Pentode, subminiature 1AM4, 1.4V, 0.025A, RF Pentode, miniature 1AQ5, 1.4V, 0.025A, Pentagrid converter, miniature 1AR5, 1.4V, 0.025A, Diode/Pentode, miniature 1AS5, 1.4V, 0.025A, Diode/Pentode 1B4, 2.0V, 0.06A, RF Pentode, Octal 1B5, 2.0V, 0.06A, Duplex Diode/Triode, Octal 1B7, 1.4V, 0.1A, Pentagride converter, Octal 1B8, 1.4V, 0.1A, Dioode/Triode/Pentode, Octal 1C3, 1.4V, 0.05A, Triode, miniature, miniature 1C5, 1.4V, 0.1A, Power Pentode (240mW), Octal 1C6, 2.0V, 0.12A, Pentagrid converter, Octal 1C7, 2.0V, 0.12A, Pentagrid converter, Octal 1C8, 1.25V, 0.04A, Pentagrid converter, subminature 1D3, 1.25V, 0.3A, triode, subminiature 1D5Gp, 2.0V, 0.06A, RF Pentode, Octal 1D5Gt, 2.0V, 0.06A, RF Tetrode, Octal 1D7, 2.0V, 0.06A, Pentagrid converter, Octal 1D8, 1.4V, 0.1A, Diode/Triode/Pentode, Octal 1DN5, 1.4V, 0.05A, Diode/Pentode, miniature 1E4, 1.4V, 0.05A, Triode, Octal 1E5, 2.0V, 0.06A, RF Pentode, Octal 1E7, 2.0V, 0.24A, Twin Pentode Amplifier (575mW), Octal 1E8, 1.25V, 0.04A, Pentagrid converter, subminature 1F4, 2.0V, 0.12A, Power Pentode (310mW), Octal 1F5, 2.0V, 0.12A, Power Pentode (310mW), Octal 1F6, 2.0V, 0.06A, Duplex diode/Pentode, Octal 1F7, 2.0V, 0.06A, Duplex diode/Pentide, Octal 1G4, 1.4V, 0.05A, Triode, Octal 1G5, 2.0V, 0.12A, Power Pentode (550mW), Octal 1G6, 1.4V, 0.1A, Power Twin Triode (675mW), Octal 1H4, 2.0V, 0.06A, Triode, Octal 1H5, 1.4V, 0.05A, Diode/Triode, Octal 1H6, 2.0V, 0.06A, Duplex Diode/Triode, Octal 1L4, 1.4V, 0.05A, RF Pentode, miniature 1L6, 1.4V, 0.05A, Pentagrid converter, miniature 1LA4, 1.4V, 0.05A, Power Pentode (100mW), Loctal 1LA6, 1.4V, 0.05A, Pentagrid converter, Loctal 1LB4, 1.4V, 0.05A, Power Pentode (200mW), Loctal 1LB6, 1.4V, 0.05A, Pentagrid Mixer, Loctal 1LC5, 1.4V, 0.05A, RF Pentode, Loctal 1LC6, 1.4V, 0.05A, Pentagrid converter, Loctal 1LD5, 1.4V, 0.05A, Diode Pentode, Loctal 1LE3, 1.4V, 0.05A, Triode, Loctal 1LF3, 1.4V, 0.05A, Triode, Loctal 1LG5, 1.4V, 0.05A, RF Pentode, Loctal 1LH4, 1.4V, 0.05A, Diode/Triode, Loctal 1LN5, 1.4V, 0.05A, RF Pentode, Loctal 1N5, 1.4V, 0.05A, RF Pentode, Octal 1N6, 1.4V, 0.05A, Diode/Power Pentode (100mW), Octal 1P5, 1.4V, 0.05A, RF Pentode, Octal 1Q5, 1.4V, 0.1A, Power Amplifier (250mW), Octal 1Q6, 1.25V, 0.05A, Diode/Pentode, subminiature 1R5, 1.4V, 0.05A, Pentagrid converter, miniature 1S4, 1.4V, 0.1A, Power Pentode (270mW), miniature 1S5, 1.4V, 0.05A, Diode/Pentode, miniature 1S6, 1.25V, 0.05A, Diode/Pentode, subminiature 1SA6, 1.25V, 0.05A, RF Pentode, Octal 1SB6, 1.25V, 0.05A, Diode/Pentode, Octal 1T4, 1.4V, 0.05A, Pentode, miniature 1T5, 1.4V, 0.05A, Power Amplifier (170mW), Octal 1T6, 1.25V, 0.04A, Diode/Pentode, subminiature 1U4, 1.25V, 0.05A, RF Pentode, miniature 1U5, 1.25V, 0.05A, Diode/Pentode, miniature 1U6, 1.25V, 0.025A, Pentagrid converter, miniature 1V5, 1.25V, 0.04A, Power Pentode (50mW), subminature 1V6, 1.25V, 0.04A, Triode/Pentagrid converter, subminature 1W4, 1.4V, 0.05A, Power Pentode (200mW), miniature 1W5, 1.25V, 0.04A, RF Pentode, subminiature 2E31, 1.25V, 0.05A, RF Pentode, subminiature 2E32, 1.25V, 0.05A, RF Pentode, subminiature 2E35, 1.25V, 0.03A, Power Pentode (6mW), subminiature 2E36, 1.25V, 0.03A, Power Pentode (6mW), subminiature 2E41, 1.25V, 0.03A, Diode/Pentode, subminiature 2E42, 1.25V, 0.03A, Diode/Pentode, subminiature 2G21, 1.25V, 0.05A, Tiode/Heptode converter, subminature 2G22, 1.25V, 0.05A, Tiode/Heptode converter, subminature 3A4, 2.8V, 0.1A, Power Pentode (700mW), miniature 3A5, 2.8V, 0.11A, Twin Triode, miniature 3A8, 2.8V, 0.05A, Diode/Triode/Pentode, Octal 3B4, 2.5V, 0.165, Power Amplifier (1.25W), miniature 3B5, 2.8V, 0.05A, Power Amplifier (200mW), Octal 3B7, 2.8V, 0.11A, Twin Power Triode (1.5W), Octal 3C5, 2.8V, 0.05A, Power Pentode (250mW), Octal 3C6, 2.8V, 0.05A, twin Triode, Octal 3E5, 2.8V, 0.025A, Power Amplifier (250mW), miniature 3E6, 2.8V, 0.05A, RF Pentode, Octal 3LE4, 2.8V, 0.05A, Power Pentode (300mW), Loctal 3LF4, 2.8V, 0.05A, Power Amplifier (400mW), Loctal 3Q4, 2.8V, 0.05A, Power Pentode (270mW), miniature 3Q5, 2.8V, 0.05A, Power Amplifier (400mW), Octal 3S4, 2.8V, 0.05A, Power Pentode (270mW), miniature 3V4, 2.8V, 0.05A, Power Pentode (270mW), miniature 3W4, 2.8V, 0.025A, Power Pentode (250mW), miniature 4A6, 4.0V, 0.06V, Twin Power Triode, Octal 512AX, 0.625V. 0.02A, AF Pentode, subminiature 5677, 1.25V, 0.06A, Triode, subminiature 5678, 1.25V, 0.05A, Pentode, subminiature 5785, 1.25V, 0.015A, Halfwave Rectifier, subminiature 5854, 1.25V, 0.03A, Power Pentode (9.5mW), subminiature 5875, 1.25V, 0.1A, Pentode, subminiature 5885, 1.25V, 0.02A, Twin Tetrode, subminiature 5886, 1.25V, 0.01A, Electrometer Pentode, subminiature 5910, 1.4V, 0.05A, Pentode, miniature 5967, 1.25V, 0.12A, Twin Triode, subminiature 5968, 1.25V, 0.12A, Twin Triode, subminiature 5970, 1.25V, 0.2A, Twin Triode, subminiature 5971, 1.25V, 0.08A, Triode, subminiature 5972, 1.25V, 0.06A, RF Pentode, subminiature 6029, 1.25V, 0.2A, Triode, miniature 6050, 1.25V, 0.12A, Triode, subminiature 6051, 1.25V, 0.1A, Pentode, subminiature 6088, 1.25V, 0.02A, Power Pentode (10mW), subminiature 6092, 1.25V, 0.05A, Power Pentode (25mW), subminiature 6121, 1.25V, 0.12A, Triode, subminiature 6147, 2.5V, 0.0625A, Pentode, subminiature 6195, 2.5A, 0.11A, Power Pentode, subminiature 6281, 0.625V, 0.02A, AF Pentode, subminiature 6286, 1.25V, 0.125A, Triode, subminiature 6418, 1.25V, 0.01A, Power Pentode (2mW), subminiature 6419, 0.625V, 0.01A, Power Pentode, subminiature 6519, 1.25V, 0.01A, Power Pentode (1.5mW), subminiature 6526, 1.25V, 0.125A, Power Pentode (375W), subminiature 6611, 1.25V, 0.02A, RF Pentode, subminiature 6612, 1.25V, 0.08A, RF Pentode, subminiature 7246, 1.25V, 0.15V, Triode, subminiature 7851, 2.5V, 0.2A, Tetrode, miniature 7979, 1.25V, 0.25A, Gas Triode, subminiature