MIL-PRF-39009 Resistors, Fixed, Wire-Wound \(Power Type, Chassis Mounted\), Nonestablished Reliability, Established Reliability, General SpecificationThis specification covers the general requirements for nonestablished reliability \(non-ER\), and established reliability \(ER\), power type, wire wound, fixed resistors which utilize the principal of heat dissipation through a metal mounting surface. These resistors have initial resistance tolerances of ??1 percent. These resistors are suitable for continuous full load operation at an ambient temperature of +25 degrees C, and when derated up to +250 degrees C \(see figure 1\). These resistors should not be used in circuits where their ac performance is of critical importance in the operation of such circuits. However, provisions have been made in particular styles to minimize inductances \(see 3.1\). These resistors will have life failure rate levels \(FRL\) ranging from 1.0 percent to 0.001 percent per 1,000 hours \(see 1.2.1.4\). These FRL are established at a 60 percent confidence on the basis of the life tests. The FRL, identified by the appropriate symbol, is referred to operation at full rated wattage at +25 degrees C, with a permissible change in resistance of ??2 percent as the criteria for failure.

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MIL-PRF-39009E

3.23 Supplying to higher FR levels. A manufacturer may supply to all higher product levels than to

which they are qualified. Parts qualified and marked to lower product levels are substitutable, with

acquiring agency approval, for higher product level parts, and shall not be remarked unless specified in

the contract or order (see table IV) (see 6.2).

TABLE IV. Product level substitution.

Product

Product level

level

substitute

S, R

S, R, P

S, R, P, M

3.24 Marking. Resistors shall be marked with the PIN (see 1.2.1) and the JAN marking. Date and

source codes shall be in accordance with MIL-STD-1285. The PIN shall be placed on the flat surface (top

or sides) of the housing, parallel to the longitudinal axis. The marking must be visible after resistor is

mounted. There shall be no space between the symbols which comprise the PIN. The PIN may appear

on one flat, and the date code, and the manufacturer's name, trademark, or code symbol on the other.

The date lot code shall provide traceability though all production operations and shall represent a specific

critical point consistently provided by the manufacturer. Marking shall remain legible at the end of all tests.

At the option of the manufacturer, the marking of resistors may be done after conditioning test (see 4.8.2).

3.24.1 JAN and J marking. The United States Government has adopted, and is exercising legitimate

control over the certification marks "JAN" and "J", respectively, to indicate that items so marked or

identified are manufactured to, and meet all the requirements of specifications. Accordingly, items

acquired to, and meeting all of the criteria specified herein and in applicable specifications shall bear the

certification mark "JAN" except that items too small to bear the certification mark "JAN" shall bear the

letter "J". The "JAN" or "J" shall be placed immediately before the part number except that if such location

would place a hardship on the manufacturer in connection with such marking, the "JAN" or "J" may be

located on the first line above or below the part number. Items furnished under contracts or orders which

either permit or require deviation from the conditions or requirements specified herein or in applicable

specification shall not bear "JAN" or "J". In the event an item fails to meet the requirements of this

specification and the applicable specification sheets or associated specification, the manufacturer shall

remove completely the military part number and the "JAN" or the "J" from the sample tested and also from

all items represented by the sample. The "JAN" or "J" certification mark shall not be used on products

acquired to contractor drawing or specifications. The United States Government has obtained Certificate

of Registration Number 504,860 for the certification mark "JAN" and Registration Number 1,586,261 for

the certification mark "J".

3.24.2 Beryllium oxide (BeO). Manufacturers which use beryllium oxide in their construction shall mark

each resistor body and resistor package with the symbol "BeO".