For pilots and avionics technicians alike, few pieces of equipment are as essential as a solid transponder. The BendixKing KT 70 is a popular panel-mounted transponder known for its reliability and its "drop-in" compatibility with older KT 76A/78A installations. However, like any Integrated Circuit (IC) based avionics unit, proper installation is critical for performance and airworthiness.
If you are planning an upgrade or a retrofit, understanding the KT 70 Installation Manual is the first step. Here is an overview of what you need to know before you turn the first wrench.
Q: Can I use the Kt 70 with a Bafang motor? A: Not directly. Bafang uses UART protocol. KT displays only work with KT controllers.
Q: Why does my speed show 0 even when moving? A: Check P2 setting. For external speed sensor, ensure magnet passes sensor within 5mm.
Q: Can I install the Kt 70 on a 52V battery? A: Only if your controller is rated for 52V. The Kt 70 will read up to 60V but may show inaccurate battery bars. Set P3=4 (auto-detect) and monitor actual voltage. Kt 70 Installation Manual
Q: My display shows “---” instead of speed. A: The controller isn’t sending speed signal. Check hall sensor wire or external speed sensor connection.
This manual covers safe unpacking, mounting, electrical connections, startup, basic configuration, and routine checks for the KT 70 unit. It assumes the installer is a qualified technician familiar with local electrical and safety regulations.
| Terminal | Function | Specification | |----------|----------|----------------| | 1 & 2 | AC/DC Power | 100–240 VAC ±10%, 50/60 Hz OR 24VDC (±10%) | | 3 & 4 | Alarm 1 Relay (NO/NC) | 2A @ 250VAC (resistive) |
Wiring steps:
1. Tiny Schematic Fonts
The wiring diagrams, especially in the printed version, use 6-point type for terminal labels. If you have less than perfect vision, you’ll need a magnifying glass. The PDF version is better but zooming is awkward on a phone.
2. Missing Real-World Installation Examples
The manual shows how to connect wires but rarely where to route them. For instance, it warns against running input wires near power cables but doesn’t show a suggested layout. A single photo or isometric drawing would help.
3. No Quick-Start Guide
There’s no separate one-page “do this first” section. You have to read all safety warnings (important, but repetitive) before reaching the actual steps. A seasoned installer might skip ahead and miss critical grounding instructions.
4. Calibration Procedure Could Be Clearer
For sensor-based models (e.g., thermocouple or RTD input), the calibration steps assume you have a known reference source. The manual doesn’t explain how to simulate a sensor signal without extra equipment – leaving DIY users stuck. For pilots and avionics technicians alike, few pieces
5. Troubleshooting Flowcharts Are Linear
Instead of decision trees, the manual uses numbered steps (e.g., “Check voltage at terminals 2-3. If no voltage, go to step 4…”). A true flowchart would be faster for intermittent problems.
| Terminal | Output Type | Connection | |----------|-------------|-------------| | 8 & 9 | Relay (SSR/Contactor) | 8 = NO, 9 = COM | | 8 & 10 | 4-20mA current | 8 (+), 10 (–) | | 8 & 11 | 0-10V voltage | 8 (+), 11 (–) |
Warning: Do not exceed 2A on relay output. For larger heaters, use an external magnetic contactor.
| Parameter | Function | |-----------|----------| | C1 | Backlight brightness (1-5) | | C2 | Auto power-off time (minutes) | | C4 | Walk mode (0=off, 1=on) | | C5 | Cruise control (0=off, 1=on) | | C14 | Current limit (A) – match controller | Warning: Do not exceed 2A on relay output
To save settings: After changing a parameter, press Power to move to the next. When finished, press and hold Power for 3 seconds to exit. The display will reboot.