RD30 intermittent depth with new transducer

[Best Mate]

I am having a problem with my RD30 using depth and temperature with an Airmar transducer.
Furuno 235DHT-LSME Airmar 44-082-1-01. My original transducer would function properly
for an hour our so then indicate bars across the screen. I found on this forum that if the sentence was highlighted on the Aux Port display the transducer was sending info, the original transducer was not highlighted during a failure so I assumed the transducer was bad.

I ordered a new transducer,which has to be purchased as a thru hull assembly for $600. I lowered it into the water over the side of the boat to make sure it was working before running 25 ft of cable. It worked fine for the 10 minutes I tested it. After the installation, the first day out, the display intermittently will show around 325 ft or 1.8 ft then back to the correct depth. The failure only last a second or two then displays the correct depth. I cruised about 5 hours today and witnessed an intermittent display a half dozen times. When there is a failure it is always around 325 ft or 1.8 ft, never in the mid range.

I am assuming the new transducer has a problem but wanted to reach out for other ideas before sending to the Furuno for testing.

 

[Snips]

Best Mate,
Just know these transducers can't really be tested on the bench. Yes, they can checked that they are transmitting but you really can't the receiver function. You can better test it on the vessel by just letting to run at certain depths. This could be a water flow issue if the digital read out is stable at the dock but blanks out if the vessel is moving.

Snips

 

[Best Mate]

Thanks, I was concerned about sending it in for testing as it is intermittent, at all conditions, underway or at the dock. It works perfect 95% of the time, just every once in awhile it goes to minimum or maximum of its range. The transducer is installed on a trawler with average speed 8 knts. I have another transducer going to a 1933C MFD and both transducers read the same value consistently. When the new Airmar transducer goes high or low, the other transducer does not fluctuate. The Airmar transducer matches the other transducer after fluctuation.

Another observation I made while underway yesterday was the temperature indication. I put the RD30 on split screen and monitored the depth and temperature. When the depth went high or low the temperature did not fluctuate, indicating the problem is only the depth circuit of the transducer.