Topic: 798c NVB Transducer Replacement

[Rev]

Hi,

I have made a mess of my transducer and it needs to be replaced. What is my best option?

Reading through here there seems to be a few options. How many of these will work, which are better, and do the different shapes reduce the rooster tail that appears?

 XNT-9-Si-180-T
 XHS-9-HDSi-180-T - HD version.

Are there any others? dont think either are the ones that originally came with the unit, as it is a bit bigger.

Any help here would be appreciated.

Rev.

[Roddy]

Rev, The HDSI will give the best pix.

Roddy

[Rev]

Does the HDSI have the same connection, and can i confirm that all functions will work with the 798c?

[Doc Stressor]

The 798 doesn't support the HD frequecies of the XHS-9-HDSi-180.

I doubt that there would be any advantage over the XNT-9-Si-180.

[Roddy]

Hummmmmm. 798ci HDSI. Then what does HD stand for?

[LocDown]

The 798 can use the HDSI transducer but it can't use all the frequencies the HDSI offers. The HDSI transducer adds the 800khz side/down imaging frequency but the 798 can't take advantage of that. As for the 798ci HDSI the HD is more or less the 2011 year designation meaning it has the direct connect ethernet capabilities

[Humminbird_Greg]

+1 what LocDown stated.
The "HD" also refers to the fact that for a 5 inch display unit, we have the highest resolution on the market.

[sonar2000]

What is the resolution numbers?
Chuck

[Humminbird_Greg]

Let’s see… if my math is correct:

640 X 640 LCD = 409,600 pixels
3.58 inch H and V display so = 12.79 square inches of display
Means 32,031 pixels per inch

[LocDown]

yes, but the 2010 798c has the same resolution as the 2011 model.

[Rev]

So the answer to the original question is it makes no difference which transducer you use, as the 798 cannot use the 800khz frequency that the HDSI transducer comes with.

[LocDown]

The HDSI transducer has a little bit better shielding....

[Humminbird_Greg]

Rev, it can make a difference which transducer you use.  The larger HDSi transducers have a longer Si element in them that form a narrower sonar beam (front-to-back) and so can show better resolution.  The problem with using this on a smaller display unit like the 798 is that not everyone can see the difference in resolution.  Those who really study their Si sonar could but not everyone can (failing eyesight makes a difference too).  Now if you made a sonar recording or a screen snapshot and viewed that on a larger display, such as your computer, then most will be able to tell the difference.

Also, the transom mounted version of the Compact Side Imaging (CSi) transducer that is normally used with the 798 unit; has less shielding than does the transom mounted HDSi transducer.  If your boat has a lot of radiated RF energy (from the motor, trolling motor or other source); the HDSi transducer could make a difference there as well.  Problem is that most will not know that they have an RF interference problem until after they have their unit on their boat and are using it.  [The trolling motor mounted version of the CSi transducer does have this additional shielding.]