hunters1,
1. As Cray said: the US2 will not work for any sort of Down Imaging (Di) sonar with any unit. Nor will the US2 produce the Side Imaging (Si) sonar beams. In the 798c HD Si units the Di sonar comes from the Si sonar beams, so if they do not work you will not get any Di sonar either.

2. The US2 sonar should work like the 2D sonar does in your 798c HD Si unit now. So if you can tune it to show fish while using your 798’s Si transducer, you should be able to do the same with the US2 transducer.

3. To connect the two units together with the I-Pilot Link to your two units you will need:
- AS-EC-QDE cable so that your 798ci HD Si unit can be connected to the other cables.
- Appropriate length Ethernet Extension Cable (AS-EC-XXE where the “XX” gets replaced by the cable length. Available in 2, 10, 15, 20 and 30-foot lengths) to connect the 798ci HD Si unit to the 5-Port Ethernet Switch and the 998 SI unit to the 5-Port Ethernet Switch. So you will need to figure out what length cable you need to connect each unit this way.
- A 5-Port Ethernet Switch (AS-ETH-5PS)
Accessories » Ethernet
- The MKR-US-8 Humminbird 7-Pin Adapter Cable to connect a Humminbird unit to the US2 sonar transducer (if you choose to do this).