This page identifies all the hardware modifications necessary to adapt a Kenwood TK-931 transceiver for operation as a 2 watt exciter for 927 MHz repeater service. Not shown here is the effort required to program the radio for the desired operating frequency. This is accomplished using the Kenwood KPG-5D programming software and KPG-4 programming
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cable, or equivalent. It also assumes that the transmitter portion of the radio was properly operating in its original frequency range prior to modification. Check-out and alignment of the transmitter after modification is recommended. The present N6EX repeater uses the TK-931 as a 2 watt exciter for a 90 watt power amplifier. The original configuration (prior to the external 90 Watt PA) used the higher power TK-931HD as the complete transmitter (approximately 30 watts output). The modifications listed below pertain to the final configuration. The above circuit was implemented on a copperclad perf-board. An LM1481 dual op-amp was used. Only one of the stages was needed. These low power amplifiers are readily available and run on a single supply. The audio interface board is installed in the front, left section of the top cavity of the exciter. This area is located near the CN2 interface connector of the radio. The board is drilled on the right front corner to coincide with the unused hole in the radio frame. Not only is this area of the radio available for convenient mounting of the interface board, but it also provides easy access to the audio and dc interfaces of the radio. DC input to the audio interface board can be taken from the CN1 connector (connects front panel to main circuit board). Switched 13. 8 VDC is on pin 2 (SB) and return is on pin 3 (GN). The audio connection is tapped into the cable running from the CN2...
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This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
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