MIL-DTL-28837C
3.4.6.7 Connection caps. All waveguide and coaxial connections shall be sealed with push-on plastic caps to
prevent both damage and the entrance of moisture and foreign material during storage.
3.4.7 Waveguide. Waveguides used in the manufacturing of the mixers shall conform to MIL-DTL-85 or (see 6.7),
as applicable (see 3.1).
3.4.8 Finish. Unless otherwise specified (see 3.1), the finish shall be as specified in 3.4.8.1 through 3.4.8.4.
3.4.8.1 RF mating surfaces. Mating surfaces shall be finished in gold, nickel or silver conforming to MIL-DTL-
45204, SAE-AMS2422, ASTM-B488, SAE-AMS-QQ-N-290, ASTM-B700 and SAE-AMS2404. Nickel shall be used
only if no other surface finish can meet the performance requirements.
3.4.8.2 External surfaces. All external surfaces excepting RF mating surfaces shall be finished in accordance with
MIL-DTL-14072.
3.4.8.3 Aluminum alloys. Aluminum alloy surfaces shall be chemically treated in accordance with MIL-DTL-5541;
however, electrical mating surfaces shall be conductive.
3.4.8.4 Pure tin. The use of pure tin, as an underplate or final finish, is prohibited both internally and externally.
Tin content of mixer stages and solder shall not exceed 97 percent, by mass. Tin shall be alloyed with a minimum of
3 percent lead, by mass (see 6.8). Lead-free silver-tin (Sn96Ag04) or antimony-tin (Sn95Sb05), high temperature
solders may be used where high temperature solder is necessary with approval of the qualifying activity. The tin
content of lead-free high temperature solders shall not exceed 97 percent by mass.
3.4.9 Weight. The weight shall be as specified (see 3.1).
3.4.10 Temperature range. The temperature range shall be as specified (see 3.1).
3.4.11 Life. Unless otherwise specified (see 3.1), the manufacturer shall submit to qualification activity evidence
that mixers are designed to operate for 1 year and degradation for this period shall not exceed specified limits (see
3.1). This evidence on each mixer for which qualification is requested shall be a certificate to the qualifying activity
and a written guaranty shall be furnished to the acquiring activity on each awarded contract. Any acquired mixer that
fails to meet this life requirement shall be replaced by the manufacturer at no cost to the Government.
3.5 Preconditioning (screened only). All screened mixers shall be preconditioned as specified in 4.7.2 and shall
subsequently meet the electrical requirements specified (see 3.1).
3.6 Burn-in (screened only). All screened mixers shall be burned in as specified in 4.7.3, and shall subsequently
meet the electrical requirements specified (see 3.1).
3.7 Electrical characteristics. When mixers are tested as specified in 4.7.4, the applicable electrical characteristics
and tolerances shall be as specified (see 3.1).
3.8 Thermal shock. When mixers are tested as specified in 4.7.5, there shall be no physical damage. Upon
completion of this test, mixers shall meet the conversion loss and isolation requirements.
3.9 Vibration. When mixers are tested as specified in 4.7.6, there shall be no evidence of damage and no vibration
induced amplitude modulation beyond the limits specified (see 3.1).
3.10 Shock. When mixers are tested as specified in 4.7.7, there shall be no evidence of damage. Upon
completion of this test, mixers shall meet the conversion loss and isolation requirements.
3.11 Seal. After mixers are tested as specified in 4.7.8, they shall meet electrical requirements specified (see 3.1).
3.12 Barometric pressure (when specified, see 3.1). When mixers are tested as specified in 4.7.9, there shall be
no evidence of damage. During the test, electrical characteristics, as applicable, shall be as specified (see 3.1).
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