DFF3 & Airmar R509LH questions

[clayt]

Hello,

Recently changed my sounder from a Garmin GSD26 to a DFF3 and I have some questions:

1. Which tap setting should I use? I was told "B" on both high and low from Furuno but recently found an Airmar document that specified "C" for certain frequency ranges.

2. Do you have any suggestions on frequency selection on both high and low?

3. How do I display water temp on my TZT14? It is not reading anywhere I can find

4. I see that this transducer has a "range" of beam widths- 9-23 degrees on LOW and 4-8 degrees on HIGH - how are these beam widths selected? Do they vary with different frequency selections? I want to use a wide beamwidth to scan for pelagics in the top 200 ft. I realize the LOW side is not the best option for detail, but if I can get a 23 degree width, I would have the largest chance of marking them with this setting, correct?

5. Accufish does nothing when selected with the rotokey. Is this function available with this transducer?

6. Can you recommend TZT setting for this transducer? Bottom Level, Gain offset, TVG Transmission rate ? The sounder seems to work OK, but im not getting the classic fish "arches" that I was getting with the GSD26.

THANK YOU IN ADVANCE!

 

[C-Bass]

Good afternoon Clayt,

Thank you for you inquiry.

I will do my best to answer your questions.

1.) Yes we would recommend Tap "B" for both the high and low frequency. Yes it is true that Airmar does publish a tap document which shows different tap settings depending on the frequency. However, setting both frequencies to TAP "B" you will not see a significant difference in performance. If you where to change the Tap setting depending on frequency and you moved the frequency and did not change the Tap setting there is a chance that you may harm the transducer. Because of this we always recommend a Tap setting that will not harm the transducer if one forgets to change the Tap when changing a frequency.

2.) This is a difficult question to answer as it will also bleed into question 4 as well concerning beam width. Please see the photos below that show a Sweep Test on the R509LH. You will notice the best returns come back around 35kHz-45kHz on the low frequency and 120kHz-130kHz for the high frequency. So based on that information and getting the most out of the transducer I would select a frequency that falls into those slots. But concerning question 4 it may not provide the accoustic beam angle that you are looking for.


3.) The DFF3 has 3 different places to wire in Water Temperature. If you are using the built in water temp from the R509 where do you have the water temp wires wired into? The high or the low frequency. If the water temp wires are wired into the High frequency on the TZT you will need to select High frequency in the menu. Please hit the home button, choose settings, choose sounder, you will want to look about 3/4 of the way down and find "Temperature Port" Choose the Temperature Port high or low depending on where you have the Temp wires wired into. Then you can add a data box that shows you water temperature, or you can make your track line color be based on water temperature values.


4.)The beam width of either High or Low Frequency will be dependent on the freuquency selection . The Rule of thumb is the lower the frequency the wider the beam width. Please. So at 28kHz the beam width will be 23 degrees port/starboard and 11 degrees forward/aft. It is good to know that the beam spread of this transducer is not conical it is elliptical. At 45kHz the beam is 13 degrees port/starboard and 7 degrees forward/aft. This information is made available from airmar. Please look at the technical specs of the R509 if you want to see the beam spreed graphs. So based on the Sweep Test photo and knowing the sweet spot of the transducers and also trying to get the largest beam angle I would suggest setting the the low frequency around 30kHz.

5.) The Accu-Fish feature is not available with this transducer.

6.) Might I ask one question before I attempt to answer number 6; What transducer where you using with the GSD26?

 

[clayt]

C-Bass, AWESOME INFO!!!

Thank you so much. I dont even really have any follow up questions at the moment. Very detailed and informative. Ill try those settings and get back to you if I have any other questions.

To answer your question about #6, I was also using the existing R509LH.

Clay

 

[clayt]

Let me know if you have any answers to #6:

6. Can you recommend TZT setting for this transducer? Bottom Level, Gain offset, TVG Transmission rate ? The sounder seems to work OK, but im not getting the classic fish "arches" that I was getting with the GSD26.


Thanks!!!

 

[Snips]

Clayt,
What C-Bass is asking is very important as a transducers beam width is one of the main factors in "fish arches".

While the R-509LH is a nice transducer it has a narrow for/aft beam width and if you had a transducer have a wider BW before that may be why your returns appear different. Below is a screen capture from a test we did years ago. As you can see the LF side of a B-265 is much wider than the LF side of the R-509, thus better arches.

Snips

 

[clayt]

Snips,

Yes, I understand that principal. I know I will not get quite the arches of a different beam angle but currently im not getting anything close to quality marks, arches or not.

IF you re-read my question #6, can you suggest TZT settings for this transducer? I think if I have the settings correct, it will mark better and more clearly...

Thanks again guys..

Clay

 

[C-Bass]

Good morning Clayt,

Thank you for the follow up.

There are really just a couple settings that you could tweak to help expand the targets on the screen in a horizontal fashion. TX rate, is going to be one of them. Make sure you have the TX set to manual and set to the fastest rate you could try 20 or "max."

Another option you could use to help expand the fish targets to make them longer would be to increase the picture advance rate, this will stretch the targets in a horizontal fashion, try to 2/1, if you move to 4/1 you will likely sacrifice a bit of clarity, but for some folks that is OK. The picture advance will stretch the targets by length not by height but it may help identify smaller targets.

Another think you could try would be to shorten the transmit pulse, try short 2 first before short 1. The when you shorten the transmit pulse it will increase the TX rate by a small amount making the TX rate a little faster.




Kind regards,

 

[C-Bass]

Good morning Clayt,

To give you a little more feedback. As snips mentioned the beam width is going to be really the ultimate variable that allows for a larger fish arches. With the for/aft beam angle really being the deciding factor with regards how fast you are moving forward and the speed of the fish and how it swims through the beam angle.

With that being said, fish arches or not as you mentioned you are not getting quality marks.

I would like to ask you a favor, if you have some screen shots of what the DFF3 looks like while fishing that would help us get a better idea of what you are looking at. If you have photos that you could post that would be great, if you don't maybe next time you are out you can take some photos of the sounder and what you are looking at for both the high and low frequency. It would also help to know what your settings are set at when the photo was taken. Auto gain, manual gain settings, TVG settings, Clutter, TX Rate, Pulse Length, Picture Advance rate etc.

Some of the other settings that you mentioned I will try to explain.

Bottom Level- This is an adjustment on a threshold that allows the sounder to give a digital bottom indication. If the sounder is having a difficult time giving you a digital bottom number you can lower the value (lowers the threshold) that determines what bottom is. Adversely if the setting is set too low the sounder could give you a digital bottom reading on a thick layer in the water column that is consistent.

Gain Offset- This setting allows you to control where the starting point of the Front Panel gain is. Sometimes there is a difference in gain between the high and low frequency. Meaning you might get the same picture (amount of stuff on the screen) with a gain value of say 20 on the low frequency and a gain value of 50 on the high frequency. You can use the Gain Offset to increase the starting point of gain on the low or high frequency so when you do set the gain value the number can be closer to each other. Hope that makes sense.

TVG- TVG is time varied gain. It can be used a number of ways but it is traditionally used to clean the screen of unwanted echoes without adjusting the sensitivity of the sounder which is the gain. When the gain (sensitivity) is adjusted by time, in with a fish finder time relates to depth, the sounder will adjust the gain based on time (depth). So when you change this setting, on a DFF3 less is more: the lower the setting the more stuff you will see, it will maximize the gain deeper and decrease the gain shallow. It can be used to clean up the screen if there are many returns in the water column that you don't care about.

TX Rate- Ideally this should be set to the fastest rate. It controls the ping rate of the sounder for a given depth the sounder is set to. The only reason to really adjust this from the highest rate is if you have another sounder on the boat and you are getting interference between the two or if you get a false bottom. But traditionally you want the sounder to ping at its fastest rate possible for the given depth that the sounder is set to.


One other question- Regarding clarity, I have to assume that you ran the GSD26 in chirp mode most of the time. Did you ever run the Garmin in not chirp mode? What did the targets look like?

I guess we are trying to clarify if we are trying to compare a chirp sounder with a non chirp sounder using the same transducer?


Kind Regards,

C-Bass

 

[clayt]

Great info. I never ran the GSD26 in non-chrip mode.

I will try your reccomendations and get some screen shots next time. I bet I see some improvement just through settings changes as you reccomended.

One more question... In the future if I want to run an Airmar 275 LHW & DFF1-UHD combo in conjunction with the DFF#/509LH, would there be interference if both were run on the high side?

I could set the DFF3 to sound at 120 or 130 and let the DFF1-UHD sweep through the 150-210 frequencies correct? Would this cause interference?

Thanks again!