RDP-149 Radar interference

[captbass28]

Finally got the 1944C radar turning and displaying targets. The only problem I have is there is a red "blob" where the boat is. I have tried everything to tune it out - unsuccessfully. My 1944C is surrounded on 2 sides by 2 vertical 1.25 inch SS tubing supports that hold the searchlight above it.
Could that be the issue. The boat was set up this way when I bought it and had an older style Raymarine CRT radar that seemed to work OK- antenna located in the same place.

 

[Johnny Electron]

The blob in the middle of the screen is called Main Bang and is normal as the radar fires its signal. You don't want to do anything to try "tuning" it out. If you mess with your timing to hide it, you will have your radar totally out of whack. Normally the radar is adjusted correct during install per the manual and after the timing and video alignments are done, you can adjust what is called the MB (Main Bang) Suppression. Many radar operators like the main bang because on open water on a calm day it might be the only thing showing your radar is working/firing. For those who don't like to see it, MB suppression is used to cover it up. You want to adjust it only enough to cover the ball of video. Over adjusting it will begin to cover up close in boat targets. If your main bang is excessively large or small it could be that your timing adjustment is way off. In some cases items on the boat reflecting can cause a larger Main Bang. If the other radar was the same exact antenna height, by the sound of it your tubing should be fine.

 

[captbass28]

Thankyou very much for the response.