tz9 and fcv 585



I currently have a fcv 585 and navnet 2 nt and I am looking to upgrade to the tz9 and a gp33 for a backup and keeping the Fcv585. I am wondering if I can link the tz9 and the fcv585 together, use one transducer for both units? Do I need a black box to run the tranducer through the tz9? Is the FCV 585 worth keeping or will the tz 9 be a better sounder. I am not planning on upgrading to the chirp right now. I have a airmar b164 through hull transducer
Keep the FCV585.
The TZT9 would require a DFF1 at the very least, and the sounder circuitry for the DFF1 is virtually the same as the FCV585. This way you will have a 9" plotter and a 8.4" sounder with no need to split or change screens. You can transfer digital information between the two units if you add an IF-NMEA2k2.

If you do go with the DFF1 the transducer can be used and will plug right in. I do not recommend a splitter box to share the transducer between machines. You could only run one at a time and will most likely have issues degrading both units. While you will get a few more sounder tricks with the DFF1 networked into the TZT9 I don't think it is worth spending the money if your FCV585 is performing the task needed.