ATU-10 is QRP, 10 W max Small, light weight and rechargeable batt powered that times out after several minutes Relays are self latching so power not required after reaching min SWR and hold that state until you change bands Best for QCX es QMX type rigs
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ATU-100 is QRO 100W max Much larger and heavy, requires an external power supply? Best for rigs like FT-857?
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Both can be reprogrammed for input power trip point to stare tuning? plus other features
