TZT 3 16/DFF-3D Interference

[Quitsa]

I used my new TZT 3 16 system today and noted a rather serious amount of noise on the HF display using the built-in sounder driving a B175H transducer. After a bit of experimentation, I found that putting the DFF-3D in standby made most of it go away. It also goes away if the interference filter is set to "High" but not at other settings or on auto.

I did not have a memory stick to take a screen capture and used my phone at the dock. You can see in the middle of the screen where I turned to DFF-3D on.

Is there any way to manage this in the settings of either device? I don't really like having to set the interference to high as it is removing other things too.

One option I did not try was to trick the TZT 3 16 sounder into operating in CW mode by using a fixed non-CHIRP transducer for the model setting. Would that work and make the internal sonar operate in CW mode at 200Hz and thus not interfere with the 165Hz DFF-3D?

 

[Quitsa]

I don't seem to have gotten anyone's attention. In the meantime, I am wondering if the DFF3D should have an external KP connection to the TZT 3? It is clear that there is provision for external KP with the DIFF-AMP from the manuals. It is not so evident from the DFF3D documentation. Wouldn't that solve the problem of interference?

 

[Snips]

Are you using a 175H that has the 12-pin plug?

Snips

 

[Quitsa]

Are you using a 175H that has the 12-pin plug?

Snips

It is a B175H but was bare wire that was spliced to a 12 pin plug. This approach was taken after consultation with one of your colleagues. The TID function seems to be working because the TZT 3 recognizes it as a B175H if the transducer setup is done on TID mode.

What we ended up doing because of the cable issues was to connect the B175H to one TZT 3 and the B175L to the other. I haven't noticed any issues with the low frequency.

 

[Snips]

If you don't connect the Orange TID wire then you could run the 175H in the CW mode. Just pick any of the other 1kw 200Khz ducers in the menu.

Snips

 

[Quitsa]

If you don't connect the Orange TID wire then you could run the 175H in the CW mode. Just pick any of the other 1kw 200Khz ducers in the menu.

Snips

Do I have to disconnect the orange wire or can I just use "model" in the setup and select a CW 200Hz transducer?

This is a bit puzzling too since you are saying to run it as though it were a non-CHIRP CW 200Hz sounder. It seems that anyone with a DFF-3D would have this interference problem with a high frequency CHIRP transducer. In fact, your combo transducers for the DFF-3D such as the 165T/265LH-PM488 have the same CHIRP high frequency overlap as my B175. The B265 which is one of the recommended transducers for the TZT 3 internal sounder has the same high frequency elements as the B175H if I am not mistaken.

 

[Snips]

Can you post a screen shot for me? The last test we did was a 275 next to the DFF3D transducer and did see much in the way the interference.

Snips

 

[Quitsa]

Thanks. It's kind of windy and rough today but I will take some screen shots tomorrow that show the interference. Was the interference filter off in your screen shot? As I h"mentioned, if I set it to "High" on my HF display it will get rid of most of the lines

 

[Quitsa]

Okay, I did some screen shots at the dock that illustrate the problem. As you can see, if the HF and DFF3D are both running, both have interference. If the LF and the DFF3D are running, the LF has no interference but the DFF3D does. If the HF is on standby or the DFF3D is on standby, the other will have no interference. These were all done with the filter off. If I put the interference filter setting to medium or high, the vertical lines go away for the most part.

View attachment 2View attachment 2

 

[Snips]

Quitsa,
I think I was using a medium setting. Currently the KP output is only available when a DI-AMP is connected. I can ask FEC about this.

Snips

 

[DeepSouthTX]

Just a side note. I currently have a DFF3D along with a B275LHW. The LHW is connected to a Garmin XSV unit at the moment. Working on getting that moved over to a TZT3. The DFF3D is connected to a 12" TZT3 - I have the exact same noise on the high frequency only as well. Low does not. On the garmin side switching noise reduction on to "low" removes the vertical lines completely. But no matter what noise filter settings I have tried on the TZT, there are only reductions in the vertical lines. But they are fairly mild with auto or high - same as your findings.

 

[Quitsa]

Just a side note. I currently have a DFF3D along with a B275LHW. The LHW is connected to a Garmin XSV unit at the moment. Working on getting that moved over to a TZT3. The DFF3D is connected to a 12" TZT3 - I have the exact same noise on the high frequency only as well. Low does not. On the garmin side switching noise reduction on to "low" removes the vertical lines completely. But no matter what noise filter settings I have tried on the TZT, there are only reductions in the vertical lines. But they are fairly mild with auto or high - same as your findings.

That's interesting to see that I am not the only one experiencing the problem. I was out today and did more experimenting. If both the DFF-3D and the internal TZT 3 sounder have interference rejection set to "high," it will eliminate the vertical lines more or less completely. There is another issue, however, which perhaps you have seen also. If the internal TZT high frequency is used in bottom zoom mode, the bottom will jump around constantly if the DFF-3D is transmitting, The instant the DFF-3D is put in standby, the HF bottom zone display stabilizes.

I think only a KP signal between the two sonars can really solve the problem.

 

[DeepSouthTX]

I have used bottom lock on the 275 but it’s on the GARMIN. It has no issues holding bottom. Even with the dff3d transmitting.