HO 4-6-6-4 CSA-2 Challenger Locomotive with Tsunami2 DCC & Sound UP #3939 (ATHG-1021)

An HO-scale 4-6-6-4 CSA-2 Challenger locomotive modeled after Union Pacific’s famous Challengers, UP 3939. This large articulated steam locomotive is equipped with a tender-mounted DCC decoder and SoundTrax Tsunami2 sound, delivering authentic chuffing, whistles and other locomotive audio for operation on DCC-equipped layouts.

Illuminated number boards and headlights light the model, with the headlight turning off when running in reverse and a tender-mounted back-up light for added realism. The Tsunami2 sound suite provides synchronized chuff, whistle, bell, blow-down, air compressor, dyno and pop-off valve effects, plus a range of user-controlled sounds, all carried through dual cube speakers for clear, room-filling audio. The model runs on both DC and DCC and offers full DCC functions with NMRA compatibility, including options to program a multi-unit lashup. It features pivoting front and rear engines to negotiate 18-inch radius curves, current pickup on all wheels, a detailed boiler backhead with printed gauges, and a robust loco-to-tender harness for durability. A minimum recommended layout radius of 22 inches ensures smooth operation, and there is an oil-tender variant that reproduces the UP Challenger’s oil-burning configuration.