在大功率时,电子管工作受栅极电子放射的限制很大。栅放的不利影响有:1.减小栅偏压;2.增加栅极激励功率;3.减小板流及输出功率。即使这些不是破坏性的缺点,至少减低了管子的使用性能。引起栅放的原因有二个:1.阴极蒸发的活性物质沉积在栅极上,激活了栅极,当栅极温度足够时引起电子放射;2.栅极受到电子轰击,温度升到很高, At high power, tube work by the gate electron emission is limited. Adverse effects of gate placement are: 1. Reduce gate bias; 2. Increase gate excitation power; 3. Reduce board flow and output power. Even though these are not destructive disadvantages, at least the performance of the pipe is reduced. There are two reasons that cause gate discharge: 1. Cathode evaporation of the active material deposited on the gate, the activation of the gate, when the gate temperature is sufficient to cause electron emission; 2. Grid by electron bombardment, the temperature rose to high ,