Read this before buying or installing the DRS4D-NXT radar!
There are two “gotchas” to installing the DRS4D-NXT that aren’t entirely obvious before you get started.
The radome MUST be installed with the bow mark facing forward; this is necessary for proper doppler interpretation. While the installation manual does state “Align bow mark on radome with ship’s bow,” it also doesn’t explicitly state that aft-facing orientations (such as when mounted on an aft-facing backstay gimbal pole) are not supported. Furthermore, the installation manual describes (and the TZT3 MFD software allows!) the “Antenna Heading Align” setting to accept values in the range of -180 to +180 degrees. This range makes NO sense if the radome must be installed only in a forward-facing orientation, and falsely suggests that arbitrary orientations are possible.
(Furuno technical support and the Furuno community forum have both confirmed the forward-facing requirement of the radome.)
In fact, I found that with “Antenna Heading Align” set between about -120 to -179 degrees, the radar echoes all but disappear:
Other angles, from between about -120 and +180 degrees do not exhibit this issue.
Furuno tech support said this of the above video:
…it appears that when you set the 120 degree offset, the radar directly beams into the metallic objects surrounding the dome (e.g. the wind gauge, etc.) which reflect right back into the array. If too many echo returns are being transmitted right back into the dome, the dome will tune down the signal processing to try and prevent the returns from damaging the sensitivity of the receiver.
I’m no expert, but this explanation doesn’t make any logical sense to me at all. Adjusting the “Antenna Heading Align” value does not alter the physical relationship between the radome and nearby objects. The radar antenna does not “beam” to a single, fixed orientation—the antenna is constantly rotating through 360 degrees. If there is some kind of interaction between the radar pulse and a nearby object, it would occur when the antenna’s rotation has it pointing at certain orientations relative to the interfering object. Thus we should see the interference no matter what “Antenna Heading Align” is set to. Similarly if we were to physically rotate the radome rather than adjust “Antenna Heading Align” (although, of course, the relative orientation of the interference would change on the radar display).
To me, this smells of a straightforward software defect. But what do I know?
It was not clear beforehand what, exactly, the “cable assembly” that connects to the radome looked like. Some online photos seemed to depict it as possibly having separate power and LAN cables. Let me assure you—it does not.
One end is a proprietary connector that goes to the radome’s pigtail. The other end has positive and negative power wires, and a male RJ45 LAN connector. Perhaps internally is a dedicated LAN cable, but if so, you cannot get to it without cutting the cable assembly’s outer sheath, and, even if you did, it wouldn’t help you much when you get to the proprietary connector.
This choice of cabling also does not make sense to me. How many installations really want to route both power and LAN to the same physical location? Seems to me you’d want the power connections to go to the DC distribution point (i.e. a DC breaker panel), and the LAN connection to go to the LAN hub or directly to the MFD. But what do I know?
The DRS4D-NXT does, however, have an RJ45 jack inside the radome. So you can—if you’re willing to invest the additional effort, and modify the cable gland—run independent power and network cabling if you so choose (see this forum post and, in particular, this view of the DRS4D-NXT internals).
Really, though, those cables should have been separate to begin with.
Note that both ends of this cable will likely give you some routing challenges as you try to work it through the conduits and tight spaces common on small vessels.
By the way, the provided inline fuse holder on the positive power wire is pretty chintzy. You’ll probably want to replace it with a proper water-resistant fuse holder.