What it is — the 38-position BERGSTIK II header
The Amphenol FCI 79821-138HLF is a dual-row 0.100-inch (2.54 mm) pitch male pin header in the BERGSTIK II series — 38 positions across two rows, all populated. Square pin contacts in phosphor bronze carry 5 A per circuit with gold or Gold GXT(TM) plating at 30.0 µin (0.76 µm) on the mating face. The push-pull fastening pairs with the matching BERGSTIK II receptacle housing for a clean board-to-board stack; without an integral locking latch the retention comes from the receptacle side, so confirm the mating half has positive retention for any vibration environment. Through-hole termination accepts a 0.200-inch (5.08 mm) post length — standard for wave or hand soldering in industrial assembly. Rated 110 V between circuits and listed UL94 V-0 for the housing material.
38 positions — where this member sits in the BERGSTIK II series
The 79821 base product number spans the BERGSTIK II dual-row family across multiple position counts. This 79821-138HLF is the 38-position member — at the higher end of the series, with other dual-row variants available in lower counts. The 0.100-inch pitch and dual-row format are consistent across the series, so a lower-count sibling shares the same foot print class and header height, differing only in circuit count. All positions are loaded, so there is no need to account for partial loading in the BOM count.
Board-to-board fit and electrical ratings
At 5 A per circuit the 79821-138HLF handles signal distribution and moderate power paths in a board-to-board stack. The 110 V rating is the circuit-to-circuit working voltage — derate both current and voltage in any high-humidity or transient-rich environment. The insulation height of 0.100 inch (2.54 mm) matches the mating pitch, giving a co-planar stack height typical of card-edge or daughtercard mezzanine arrangements. The 0.430-inch (10.92 mm) mating length and 0.730-inch (18.54 mm) overall contact length define the engagement depth — useful for checking clearance in dense enclosures.