HELIX 9 SI comes standard with the Compact SI xducer ...which is tuned for 455kHz ...
HELIX 9 SI can indeed transmit 455kHz and 800kHz (thru the Compact SI xducer) when the Connected Transducer selection under the Sonar tab is set to Hi Def Sidescan ... but performance at 800kHz thru the Compact SI xducer will be so-so ...
You can exchange the included Compact SI xducer by calling HB before you open the transducer hardware baggie and set up exchange for the XHS 9 HDSI 180 T Hi Def Sidescan xducer ... which is tuned for 455kHz and 800kHz ...
https://www.humminbird.com/support/f...sducerExchange
Rickie