The red line is the primary damaging high frequency arc path. The path goes through tubes, out through the
filament coupling capacitors. It then travels through the tuned input circuits to the RF input, and that is where your
radio is connected. The arc path is NOT out through the relay control line; a relay line isolation device will not
prevent or reduce arc damage. The arc path is NOT out through ALC; using or not using ALC will have no effect on
radio damage.
(Fig 1)
This kit does the following:
1.)
Adds two “150 volt” Gas Discharge Tubes from filament directly to chassis at the tubes. The
Littelfuse gas
discharge tubes (GDT) surge arrester devices protect personnel and
equipment from damaging high
voltage transients induced by lightning, inductive switching, or electrostatic discharge.
This limits
transient to about 350 volts absolute peak. Any substitute GDT’s should be vetted for performance. GDT’s
do not clamp. GDT’s ionize at a certain voltage, becoming a near-short once ionized
2.)
Instructs you to directly ground grids in older version that had grid equalizing resistors. This is a critical
update. The grids should always be directly grounded. THIS IS A MUST DO in any grounded grid amplifier
that floats grids from chassis.
3.)
Increases or adds bias. Bias improves tube life and efficiency without noticeably hurting IMD with 3.9 volt
5 watt Zener bias diodes. If your amplifier has a string of bias diodes, you add only ONE of these diodes in
series with the white center tap. If your amplifier does not have a string of bias diodes on the input board,
