given the post date, i hope you already have it working. But, if it's going to be cable, has to be coax, as 734a. Never saw ds3 on anything but fiber or coax ... don't think it's possible.

If 1k' is too long, suppose you always have the option of converting to fiber, then back. search coax 734 on Internet and will find many suppliers.

(please see message thread at https://www.cm.nu/~shane/lists/comp.dcom.telecom.tech/2000-10/0310.html for a bit more discussion about limits)