Do not get any images on the radar screen

There are a couple of things that could cause the radar to power off when going into the transmit mode.

The first thing to eliminate is input power. When in the standby mode the radar draws less current than in the tx mode so if you have low voltage for whatever reason, that could cause a shut down. Check all connections and measure the voltage to the unit while it is on.

A problem with the antenna motor or gear box could also be the problem. The antenna doesn't rotate unit the unit is switched to the tx mode. You would need to remove the dome cover (with unit off) and verify that the array will turn freely by hand. Typically, a bad motor will not cause a shut down but a physical obstruction could.

Focus on the power issue because that's the most common problem. Be aware that you need to measure the voltage as close to the radar display as possible and watch the voltage as you switch the radar from standby to transmit for a quick dip in voltage.

Either a weak magnetron, water in wave guide or most likely radar settings are not right.
You have an 1834C, so a 4KW dome, right?
Radar antenna should be set to type "B" in Radar Set-Up menu
Access this menu by holding the Menu button during turn on and then choosing Installation Mode, allowing access to Installation Set Up Menu, where the Radar Set Up Menu is located. Be sure to do Optimize Radar, while you are in there.
Learn to use Sea Clutter and turn off AC Auto Tune.
Good Luck!
John 847-746-0100

There is a seal on the antenna scanner shaft, just below the seal there are two bearings, thou the antenna are enclossed moisture still get inside and get to these bearings. Try and get a small amount of wd40 on the bearings, if not, you will soon begin to see false echoes on the screen because the motor on the scanner or antenna will begin to work harder causing a drag causing these echoes. Good luck.

How old is the radar antenna? When the echos are weak that is a sign of a failing or weak magnetron. Have you gone into the system diagnostics page to read what the signal strength of the radar is?

it cannot determine a heading, have you also damaged an internal antenna or positioning / gps device inside it? It is unsure which direction it is pointing in but uses triangulation to determine this.

That requires either an electronic compass unit, or gps to achieve correct heading and hence correct orientation of the radar image

It sounds like voltage loss could be your issue. You need to find the "Y" cable under the dashboard and measure the voltage at the point where it connects to the main 12V supply. Keep the meter on and then spin up the radar. If there is a fuse (there should be) make sure you are measuring on the radar side of the fuse. If the voltage drops off as the radar slows, you have found your problem. If the voltage stays constant and the connections are sound at the terminations in the radar pedestal, I would recommend you send the pedestal in to Raymarine.

If this is on the radar screen, you'll have to set your heading alignment on your radar. The radar may be 180 degrees out. if this occurs on the plotter, then if you have a heading sensor attached or an autopilot, your heading may be off.

Hello.

According to the operating manuals of the two radars (found on Furuno's Website (www.furunousa.com), they do use the same antenna cable.

Hope this was helpful.

This is a belt driven antenna. That would be the first thing to check, to be sure it’s not slipping. This should be easy to see if the motor is spinning but not the antenna that would be the problem.
I don’t recall if this model uses a “toothed belt” or not, but if it does check the entire belt for missing teeth, replace as necessary.
The next thing I would check would be the flywheel under the antenna. Check it for any signs of corrosion around the bearing. Remove the drive belt and slowly rotate the antenna see if you can detect any friction anywhere is you rotate the antenna. You could try a spray lubricant (like WD-40) but be careful of overspray, keep it off any electronics!
The next thing I would check would be corrosion on any power connections (all the way back to the main power and the fuse. Corrosion on any of the connections will lessen the current flow and make the drive motor weaker. Sometimes corrosion and salt can be cleaned off with a “contact cleaner” (or alcohol in a pinch) but if there is heavy damage you might have to replace the connectors completely. Be sure to remove all power before disconnection and connectors and be sure that they are dry before reapplying power.
Lastly (and most expensively) you might need a new motor.
If you operate in saltwater, corrosion on the connections would be my guess for the cause but I still would check these in order, from easy fix, to the expensive fix.
When you replace the dome be sure the O-ring gasket is in good condition and well lubricated with silicon grease before you close the unit. Replace the O-ring if you see (or feel) and nicks or compressions in the rubber. Take care that there are no twists in the O-ring when you reinstall it.