Continental Electronics 816R - Eimac Tube Bulletin

PRODUCT BULLETIN
EIMAC 4CX15.000A AND YC130
MARCH 23, 1990
INTRODUCTION:
EIMAC has learned more about the best way to operate these tubes in regard to filament management. These revised
operating instructions conflict with the advice given in the original EIMAC Application Bulletin AB-18, "Extending
Transmitter Tube Life". AB-18 recommends against operating the filament at a voltage less than 95% of nominal.
The following instructions supersede all previous suggestions and instructions. Specifically, you should lower the filament
voltage after the first 200 hours of operation. There is no longer a lower limit of 95% of full filament voltage. This is the
principal change in Eimac Product Bulletin AB-18. After operating a new tube for 200 hours, the filament voltage should be
reduced to the power emission knee required for your output power.
WARNING
PROCEDURE:
High voltage is used in high power equipment.
High voltage can cause severe injury or death.
Insure that all circuit breakers are off and
primary power is disabled when making
adjustments inside the transmitter.
Discharge all power supplies before making any
adjustments.
First stabilize the new tube emission by operating it at rated filament voltage for a minimum of 200 hours. Raise the
transmitter output power to approximately 105% of normal power. Carefully lower the filament voltage in 0.2 volts steps,
pausing for about 30 seconds after each decrement, until you see a significant (greater than 2%) change in power output or
plate current This is the filament emission knee. Now raise the filament voltage 0.2 volts above the knee voltage. This is the
correct filament operating voltage for your power output. Operation at this reduced filament voltage insures maximum
possible tube life.
Check for a change in the filament voltage knee one week after you lower the filament voltage. Keep the operating voltage
0.2 volts above the knee. Repeat this check monthly throughout the life of the tube.
NOTICE:
It is imperative that the EIMAC "Warranty Claim Service Report" be completed and returned with all tubes that are still
in warranty. This information provides Eimac and our engineers with information concerning tube performance and service
obtained.
Note:
The preceding information was taken from EIMAC Product
Bulletins for the 4CX15.000A and YC130 tubes dated March 23,
1990.
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