In the article, we will consider a 6H8C double triode, characteristics and application features. This radio tube is intended for use in the ULF. It is installed in the pre-amplification stages of the ULF and phase inverters. A lamp is also used in a variety of pulse designs, TV signal receivers, and measuring equipment. The cathode has an indirect glow of the oxide type. The lamp can work in any position, despite the glass case. The base has a key and 8 pins. The maximum resource is 500 hours.
Electrical data
The characteristics of the 6H8C radio tube are as follows:
- The input / output capacitance of the first triode is 2.8 pF / 0.8 pF.
- The input / output capacitance of the second triode is 3 pF / 1.2 pF.
- Feed-through capacitances of the first / second triode - 3.8 pF / 4 pF.
It is also necessary to highlight the following parameters of the radio tube:
- The voltage on the filament is not less than 6.3 V, but not more than 7 V.
- The maximum voltage at the anode is 250 V.
- The grid offset is 8V.
- The anode current is 9 mA.
- The glow current is 600 mA.
- The steepness of the characteristics is 2.6 mA / V.
- Internal resistance - 7.7 kOhm.
- The maximum gain is 20.5.
Use as ULF
When designing a preliminary stage of the ULF, you need to know that when using a load on a low power anode, the gain is significantly reduced. In this case, the frequency response expands significantly. If the anode voltage is relatively large, the gain increases, the frequency response of 6H8C becomes narrower.
A capacitor that blocks resistance in the cathode circuit is best used electrostatic, capacitance in the range of 10 ... 50 ฮผF.
Fine correction of 6H8S
A radio tube can work in thin correction schemes. In this case, the true gain is only a few units. Potentiometers, which adjust the high and low frequencies, are installed in the grid circuit. When the rotors of the variable resistors are in the middle position, the characteristic is uniform and lies in the range of 30 Hz - 15 kHz.
It is worth noting that when constructing circuits, the 6H8C lamp can be replaced by analogues, the dimensions of which are much smaller. Ideally suited for this purpose 6N2P.