I have a helix 5 si unit for my boat and want to use the same head unit for my kayak, so I was looking to by a 2nd transducer, power cable and mount.  Can I use a standard transducer with the SI unit or do I need the SI transducer.  I didn't want to spend much, and the standard transducer is much cheaper. 

Yes you can use a dual beam 2D sonar transducer with a SI unit. Just change the Connected Transducer setting to Dual Beam in the Sonar main menu. The SI transducer is the standard transducer for a SI unit. It comes with the XNT 9 SI 180 T but will produce sharper images with the XHS 9 HDSI 180 T.

The transom 2D transducer is the XNT 9 20 T.

Always change the Connected Transducer setting to match the transducer. You can damage the unit processor by not doing that when a SI transducer is not connected.

Good to know the other transducer will work, and thanks for the warning to change transducer type on the unit.

On June 27, 2016 at 7:50 PM, Wayne P. said:

Yes you can use a dual beam 2D sonar transducer with a SI unit. Just change the Connected Transducer setting to Dual Beam in the Sonar main menu. The SI transducer is the standard transducer for a SI unit. It comes with the XNT 9 SI 180 T but will produce sharper images with the XHS 9 HDSI 180 T.

The transom 2D transducer is the XNT 9 20 T.

Always change the Connected Transducer setting to match the transducer. You can damage the unit processor by not doing that when a SI transducer is not connected.

I just ordered the HD transducer for my Helix 5 SI unit.  Am i correct that i will not need to adjust any settings from the transducer that comes with the unit originally?

Yes you are correct, the SI crystals are longer and produce a thinner SI pulse. The thinner pulses "see" less stuff per pulse so the created images are sharper. The Helix 5 just has 455 kHz Imaging capability. So does the Helix 7 SI GPS.

Larger units have both 455 kHz and 800 kHz Imaging frequencies and is why that transducer is standard with those models. BUT the HDSI will improve the images of any SI unit that comes with the standard Compact SI transducer like the Helix 5 SI GPS does.

If you had purchased the Helix 9 SI GPS, that comes with the Compact SI transducer, but has the 800 kHz capability. With a transducer upgrade, then you would select Hi-def Sidescan it its menu to add the 800 kHz capability.

The Helix 10 SI GPS and Helix 12 CHIRP SI GPS come standard with the HDSI transducer.