MIL-R-19365E
3.4.2.3 Effective wire coverage. Effective wire coverage is the winding length on the tube between points of departure from the normal winding pitch.
3.4.3 Terminals. Terminals shall be treated to facilitate soldering. They shall be firmly secured to the tube and shall not be solely dependent on the protective coating for mechanical anchorage. All terminals shall be so designed as to permit the secure crimping or hooking wire without depending upon soldering for mechanical strength. They shall support the wire without deformity. All terminals shall be radically straight and within 10 degrees of a plane passing through one of the terminals and the longitudinal axis of the resistor.
3.4.3.1 Adjustable terminals. Adjustable terminals shall make positive continuous contact with the turns of the winding, and shall be designed for fastening securely in the desired position.
3.5 Threaded parts. Where applicable, all threaded parts shall be in accordance with FED-STD-H28.
3.6 Voltage rating. Resistors shall have a rated direct current (dc) continuous working voltage, or an approximate sine wave root mean square (rms) continuous working voltage at commercial line frequency and waveform corresponding to the power rating, as determined from the following formula:
E = PR
Where: E = rated dc or rms continuous working voltage.
P = power rating (see 3.1). R = nominal resistance.
3.7 DC resistance.
3.7.1 Total. When resistors are measured as specified in 4.7.1.1, the total dc resistance shall be within 5 percent of the nominal resistance value (see 1.2.1.3.1 and 3.1).
3.7.2 Maximum engageable. When resistors are measured as specified in 4.7.1.2, the dc resistance shall be within 20 percent of the value recorded in 3.7.1 for resistors of 2-inch nominal lengths or less, and within 10 percent of the value recorded in 3.7.1 for resistors over 2 inch nominal lengths.
3.7.3 Resistance value deviations. All maximum deviations as specified in this section are to be considered absolute units with the exception of contact resistance adjustments.
3.8 Resistance temperature characteristic. When resistors are tested as specified in 4.7.3, the resistance temperature characteristic shall not exceed ±0.040 percent/OC. For resistors having a resistance value up to and including 0.25 ohm per square inch of winding area, and shall not exceed ±0.026 percent/OC for all other resistors.
3.9 Temperature. When resistors are tested as specified in 4.7.4, there shall be no evidence of mechanical damage. Softening of solder during the test, except where it is used solely as a tinning agent, shall be consider a basis for failure.
3.10 Dielectric withstanding voltage. When tested as specified in 4.7.5, resistors shall not flashover, show any evidence of mechanical damage, arcing, or insulation breakdown nor change in resistance in excess of 0.1 percent.
3.11 Insulation resistance. When resistors are tested as specified in 4.7.6, insulation resistance shall be not less than 100 megohms.
3.12 Power rating. When tested as specified in 4.7.7, resistors shall dissipate the rated power input exceeding the maximum applicable hot spot surface temperature (see table I). (The hot spot is the point or elemental area of maximum temperature on the external surface of a resistor.) There shall be no evidence of intermittent open
circuiting in the winding (see 3.1), and the change in resistance as a result of this test shall not exceed 0.5 percent.
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