Radar Heading Slowly Spinning Around? (1943C 4' Open Array)

[Anonymous]

My open array radar heading (as displayed on my Navnet display) started to spin around clockwise? It takes ~30 seconds for the forward heading detail to spin clockwise around before it is at the top again. Any ideas?
My radar has served me well for the past 7 years but out of the blue this started to occur.
Thanks,
Mark

 

[Johnny Electron]

It sounds like the bearing pulses from the motor are not all there. The motor has an bearing generator that puts out 360 pulses. If it puts out say 350 pulses then you would have a 10 degree spin per rotation until it makes a full turn. It could also be that the display is having problems picking up all the pulse (say cable has corrosion) or the display processor is having problems processing them. It would take some troubleshooting. Normally a dealer would have a spare motor to swap in and try or place a radar simulator box on the display for testing. You might want to contact you nearest dealer.