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Phiradar FF688C

Phiradar FF688C

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Dual Beam984 ftNo

The Phiradar FF688C is a basic fish finder unit. In terms of features, it can be compared to the older Humminbird Piranhamax 197c. It is not a plotter unit, so it does not have GPS, chart, or other navigation features, just the dual beam 200/83 kHz sonar. It does, however, include a transducer.

Technical Details and Specifications

  • Display: 3.5″ diagonal, 18-bit color range, 240H x 320V pixel resolution, with LED backlight
  • Sonar: Dual Beam
  • Depth Capability: 984 ft (300 m)
  • Frequency and Coverage: 200 kHz / 20° and 83 kHz / 60°
  • Transducer: Included
  • Power Output: 100 Watts (RMS) / 800 Watts (PTP)
  • Power Input: 10-18 VDC
  • GPS: No
  • Charts: No

Sonar and transducer

As we’ve mentioned above, the Phiradar FF688C offers basic dual beam sonar. It operates at 200 kHz and 83 kHz; it does not have CHIRP technology, so the sonar pulse is fixed. Also, in case you’re wondering, it cannot use both sonar frequencies and beams simultaneously, but you can easily swap between them.

The unit includes a basic dual beam transducer which has a transom mount, 20 ft (6m) of cable, and an internal temperature sensor. This being said, the control head can also display the water temperature.

The transducer uses conical beams for the two frequencies. Their coverage is 60° @ 83 kHz, and 20° @ 200 kHz, similar to the XNT 9 20 T transducer included with the Humminbird HELIX 5 Sonar unit. This being said, it is recommended to use the 83 kHz mode if you want to scan a wider area, and the 200 kHz mode if you want more focus.

The system’s maximum depth capability is 984 ft (300 m). Although this is not mentioned, this depth capability probably stands for freshwater and perfect conditions. In saltwater, its depth capability should be lower.

In terms of sonar functions, the unit makes quite a few available. Among them, we can count Amplitude Scope (A-Scope), Fish Identification, Auto Zoom Bottom (or Bottom Lock), Fish Alarm, and Depth Alarm.

The A-Scope function plots the depth and intensity of a sonar return. It appears on the right side of the sonar view indicating the returns from the bottom, structure, and fish that are within the transducer beam. The Fish Identification function assigns little fish icons to the suspended targets which are interpreted as fish. Depending on the size of each fish target, the unit assigns smaller or larger icons to them. Also, each fish icon has its depth displayed close to it.

Auto Bottom Zoom (or Bottom Lock) allows you to set how much of the water column is shown on the sonar view, and will continuously graph the bottom at a constant point. And finally, the unit offers the possibility to set up an audible alarm when it detects a fish, or when you reach a certain depth.

Control unit features

The Phiradar FF688C is a small fish finder, featuring a 3.5″ display with a pixel matrix of 320V x 240H. It is a color unit (18-bit) and has LED backlight which offers better readability in direct sunlight. It’s also designed to withstand incidental water exposure.

The unit is keypad operated (it does not have touchscreen technology). It has buttons for quick sonar zoom, quick menu access, change view, power ON/OFF, and a larger direction button at the center. Depth can be set either to feet or meters. It also has multi-language menu settings, with 14 languages available (English / Russian/ French / Chinese / Japanese / Finnish / Polish / German / Italian / Spanish / Dutch / Korean / Swedish / Greek / Danish).

The unit includes a standard tilt mount. It requires a 12V battery as a power supply (which is not included). An in-dash mounting kit is not available for it. Also, in case you’re wondering, the power cable is approx. 5 ft. (1.5 m).

The Pros

  • Dual beam sonar (83/200 kHz);
  • Transducer with transom mount and internal temperature sensor is included;
  • Depth capability up to 984 ft;
  • Fish Identification, A-Scope, Bottom Lock, Fish Alarm, Depth Alarm;
  • Color display;
  • Fairly decent sonar imaging for a small unit;
  • Basic waterproofing;
  • Standard tilt mount included;
  • Multi-language menu settings (14 languages);
  • Easy to install.

The Cons

  • No unit cover;
  • No trolling mount for the transducer.


The Phiradar FF688C is a basic fish finder (no GPS) offering dual beam sonar (83/200 kHz) and a dual beam transducer with transom mount and an internal temperature sensor. The unit makes available several standard sonar functions such as Fish ID, Bottom Lock, Amplitude Scope, Sonar Zoom, Fish Alarm, and more. It’s an inexpensive fish finder, great for both freshwater and saltwater.

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