Installation of IFD in Kenwood TM455

Posted on Feb 6, 2014

Feed the cable through some hole in the chassis to the opposite side There, between fan and rear panel, you may install the IFD board upside down. Use a thin and flexible isolating material, as PE or PVC to prevent short circuits. The board should be placed close to the fan because of the form of the cover. The coax comeing from TP 401 goes to IFD

Installation of IFD in Kenwood TM455
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input (shield to IFD ground). IFD power-supply can be tapped at any point, where 12 volts are accessible. (see picture: red wire) Results: You can receive high speed FSK data signals without problems after this modification. Here the eye diagram of a 76800 Baud FSK signal, received with TM455 and IFD. After reinstalling all covers, the transceiver should work exactly as before. Adjust the output level of the TNC to get the desired frequency deviation / modulation index. Do not overmodulate. The RSSI output (if connected) should be near zero volts (<0. 1 m V signal) and go up to 4 volts (1 mV rf input) A: There is an unconnected pair of pins on the printed circuit board (M60/M61). These pins can be connected to the joint of R52/C52 (DET out) via a 100 kW resistor to pin M60. The voltage measured at this pin will depend on the center frequency of the received FM signal. A: The TNC2 with the Z80 processor cannot decode signals beyond 19200 Baud. The newer TNC3 or TNC31 series is capable of receive and transmit baudrates up to 1 Mbit/s. There are modems with all common baudrates (9600, 19200, 38400, 76800, 153600 and above). Special modems with different RX and TX speed (e. g. TX 9600 / RX 38400 for UO-12) are also available. When using WISP software with a TNC3 packet controller, you may use the modem 2 for receiving and modem 1 for transmitting. As WISP uses kiss-mode, both modems are received simultaneously, the data will...

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