Simrad 4G radar with Scanstrut Backstay Mount

[gdavids]

I have a Simrad NSS system with a 4G radar that is mounted using the Scanstrut self-leveling backstay rig. While this mounting system was certainly pricey, it seemed like the best way to go at the time. However I seem to have an issue that might be related to this.

I will often get a "ghost image" at a 0 degree bearing at a similar distance to another real object that is generally located within 30 degrees of the centerline. So if there is an object (boat, buoy etc) 1.5 miles out at 25 degrees from the bow, The radar will often show another blip on the centerline at 1.5 miles out. As you can imagine, this would certainly be an issue worrying about dodging an object in thick fog that does not exist.

I have played around with the standard tuning controls, including the "local interference" filter without much success at getting rid of this problem. If I strongly crank up the filtering, or down the gain, I can get rid of it but also lose other real targets in the process.

Since the mount is the style that supports the dome behind the backstay, there is a stainless tube a bit over an inch in diameter going right in front of the dome. I have to wonder if this is the cause of the problem. Anybody else with the same radar and mount? If this tube is the issue, any thoughts on if there is some treatment I could do to it to lessen this phenomena?

Other than this concerning problem, I really like this whole system.

Greg Davids

[Neptune's Gear]

I have a 3g Unit on a custom made backstay mount. It has 2 stainless tubes at about 30 deg angles - no similar issues as you report. Mount is behind the backstay in a similar manner to yours.....