Tuning AL811H with TOF module and Pulser

This video shows how easy it can be to tune an AL811H with a tuning pulser and TOF. The same results can be achieved through use of short steady carriers of less than 10-15 seconds interspersed with cool down periods.

The graphs also show the change in anode dissipation when tuned at reduced drive levels. It is important to note dissipation, or anode heat, does not linearly decrease with reduced drive. Duty cycle is far more important than drive power for maximum tube life.

Reducing or limiting drive power will not necessarily increase tube life. As a matter of fact the anode heat, which is the real thing that harms 811 tubes, increases as drive power is reduced. Please look at the graphed data, which shows power output vs. dissipation for a given tuned condition.

Nearly all linear amplifiers follow the trend where dissipation increases with drive reduction, a peak is crossed, and then dissipation falls. Sustained steady operation on the "dissipation hump" should be avoided.

The TOF module does two important things:
1.) It allows you to see the real grid current on any mode, even pulses or voice. Grid current is the single best indicator of proper tuning

2.) It disconnects the amplifier if things go too bad for grid current. This prevents tank circuit damage from mistuning