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Sitex ES502

The Sitex ES502 black box sounder is designed to provide sonar data to a number of Sitex chartplotters, including the full ColorMax line, that are not equipped with an internal fish finder.

We reviewed the ES502 black box fishfinder with an Airmar P58 transducer connected to a Sitex Colormax 5E chartplotter set to show sounder data full screen with A-scope turned on.

sitex es502 black box sounder

Sitex ES502 Black Box Sounder

Pressing a soft key while on the chart page of the 5E or any other Sitex ColorMax chartplotter brings up additional soft key functions to select full or split screen sounder display pages.

Data from the black box was transferred to the Colormax 5E display via cabling. We found it neccesary to configure the ColorMax display unit before it would recognize the black box fishfinder.

This unit is capable of producing 500- or 1000-watts RMS of output depending on the transducer coupled to the unit.

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The ES502 black box measures about 7-inches square and a tad over 2-inches high, it is splash resistant but not waterproof and must be mounted in a dry area.

This sounder has all the basic fishfinder functions plus a few more sophisticated features like 2x and 4x zoom, bottom lock, and shift. It also has two automatic gain setting as well as manual.

sitex es502 black box sounder on sitex colormax 5 display

On The Water Performance

The Sitex ColorMax 5 screen shot shows the high frequency output from the ES502 just after passing over our ping pong ball targets.
Even the narrow beam width of the 200 kHz display had no trouble finding all three of our test targets. Although in our opinion they are oversized when compared to the actual target size. We achieved our best results with the ES502 by using manual range and gain settings.On the right side of the screen you can see the depth markings and the A-scope display. We’d have preferred the depth was marked at each ten feet rather than having to interpolate the numbers.

Although we did not go out and test in these depths we’d expect this machine to read to at least 300 feet with the 200 kHz pulse and to over 1000 with the 50 kHz setting.

Overall on the water performance of the ES502 was good for a unit in this price range.

One very interesting feature is the ability to set manual depth range by the foot. This gives you virtually unlimited range options and makes it easy to optimize the view.

On our initial passes over the sounder test objects the Sitex marked the targets well but had too much extra noise and clutter displayed.

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To improve the picture we reduced the gain manually to about 50%, this produced a much cleaner picture of the test target minus most of the extraneous noise.

It is a common occurrence to use manual gain on a fish finder to improve the picture of the fish, bottom, and structure being displayed.

We rated the Sitex ES502 black box good for presentation even on the small screen 5E. You should expect even better results when using this black box sounder with a bigger screen Sitex chartplotter.

Sitex ES502 Specifications

Maximum Power (Watts RMS)500 / 1000
Frequency (kHz)50 / 200
Transducer Used for TestAirmar P58
Auto Depth RangingYes
Manual Depth RangingYes
GainAuto(2) / Manual
Bottom LockYes
Warranty Period (Years)2-parts / 1-labor


The four soft keys on the Colormax 5E are fully functional in sounder mode and let the user quickly adjust gain, range, and frequency.

Zoom is available by using the range keys and cursor pad. The remaining sounder functions can be found on the fishfinder setup menu with a single press of the menu button.

We found the soft key functionality and range buttons made the Sitex sounder easy to operate.

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We rated this Sitex black box sounder good for usage.

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