798 Replacement

[ko4nrbs]

Going to replace the 798 I’m using on the bow this spring. In order to have sonar, SI and DI for $1,200 dollars or so what are my options? Like to have as large a screen as I can afford.

The transducer is mounted on the trolling motor. It’s the TM-HDSI transducer. Is it compatible with the new units?
Bill

[Wayne P.]

The MEGA SI units use a transducer with a Down Imaging crystal. The HDSI does not have Down Imaging.
You can dumb down a MEGA unit with that transducer though.
The Helix 5 and Helix 7 still use that transducer.
The Helix 9 CHIRP MEGA SI GPS G2N would be the largest and close to your budget.

[ko4nrbs]

The MEGA SI units use a transducer with a Down Imaging crystal. The HDSI does not have Down Imaging.
You can dumb down a MEGA unit with that transducer though.

So it would not have DI but would have SI and Sonar??

Thanks Wayne!!
Bill

[Wayne P.]

No, you would not have true DI created by a Down Imaging crystal. You would have composite DI views like you have now with the HDSI transducer.

[ko4nrbs]

No, you would not have true DI created by a Down Imaging crystal. You would have composite DI views like you have now with the HDSI transducer.

I could live with a composite DI as long as SI and Sonar are available. I'll check on the compatible transducer for the Helix 9 CHIRP MEGA SI GPS G2N and see how much they are. Are they about the same size as the TM-HDSI? If so I could use my existing Transducer Saver.
Bill

[Wayne P.]

I could live with a composite DI as long as SI and Sonar are available. I'll check on the compatible transducer for the Helix 9 CHIRP MEGA SI GPS G2N and see how much they are. Are they about the same size as the TM-HDSI? If so I could use my existing Transducer Saver.
Bill

If you are purchasing a new MEGA SI unit, it comes with the transducer--XM 9 20 MSI T= about $350 MSRP.
It is 1" longer than the HDSI and different shape. The transom bracket is different than the HDSI transducer also.

The Transducer Shield and Saver for the MEGA SI transducer is TM-HX-3 and is more than double the price of the TM-HDsi mount.

[ko4nrbs]

If you are purchasing a new MEGA SI unit, it comes with the transducer--XM 9 20 MSI T= about $350 MSRP.
It is 1" longer than the HDSI and different shape. The transom bracket is different than the HDSI transducer also.

The Transducer Shield and Saver for the MEGA SI transducer is TM-HX-3 and is more than double the price of the TM-HDsi mount.

Can the XM 9 20 MSI T be used on the trolling motor as well as the transom?
Thanks,
Bill

[Wayne P.]

Can the XM 9 20 MSI T be used on the trolling motor as well as the transom?
Thanks,
Bill

Yes, with the Transducer Shield and Saver mount or the Humminbird AD MTM adapter.
https://humminbird.johnsonoutdoors.c...r-hardware-kit