AL80B install


Most amplifiers require a special TOF module. The wire colors
and resistor values are different. Be sure you have the correct TOF module.

Limited sales volume have made this impossible to
produce. This is no longer available.

If you have the TOF with OL relay, you must alter standby
switch wires.

LED Warning Indicator

The LED warns by illuminating when exceeding the typical
maximum peak grid current for proper linear amplification. R6 on the TOF board
sets the illumination point. 4700 ohms is approximately 190 mA, but this varies
slightly with component tolerances. (The grid meter is not perfectly accurate,
and other components have tolerances.) If you slightly open
the LOAD control clockwise and the LED does not go back to occasional sharp
quick flashes, or does not stay completely off, the amplifier is being
overdriven. Reduce the drive power until the LED just flashes occasionally, or
stays completely off.

The warning LED may occasionally
flash on voice peaks from radio power overshoot. This is generally not harmful
or disruptive to others. If the LED illuminates longer than very brief flashes
or blinks, or stays on with every word, the amplifier is being overdriven or is
mistuned. The exact level where flashing occurs varies with tube.

The LED can be mounted between the panel meters. The flash is
much more noticeable than this photo.

AL80B grid meter warning red


Tools required:

#1 and #2 Phillips

Soldering equipment with small rosin flux solder,
preferably WRAP2 rating but any electronics solder will work

Included in kit:

TOF1 with precut wires

two small cable ties

Heat shrink





Remove the power plug from the outlet, and after making sure
the HV meter has reached zero, remove the cover.






























Next two steps for TOF with overload relay only!!

TOF with grid trip overload relay system



TOF modification for AL80B




On all units continue



Mount LED





Operation notes:

The LED should light solidly at 200mA. This varies with tube and component
tolerances. This is the grid current point where splatter rapidly gets worse.
You must either reduce drive power, or increase loading setting. Do not push the
amplifier to maximum possible RF output power, leave a few hundred watts

The overload disconnect trips off at 25% more current, approximately. This
disconnect is to prevent damage, not splatter. It is reset by switching the
amplifier to standby, and then back on.