Introduction: QYT KT8900 PACKET MOD

QYT KT8900 mod for PACKET

This is a chinese cheap 20W 144/440MHz mobile radio, but have two wrong design thinks to connect friendly this unit with your sound card because them not have a external speaker jack, also the squelch operation is too slow.

A good idea is take the audio signal from the discriminator directly, here you have a opensql signal, a clean and good quality and audio signal.

To make this modification please use the ht9170d chip (used to decode a DTMF signaling) also use empty pin 8 on the mic connector with a 2,2uf electrolitic capacitor to audio coppling.

Step 1: Open the Radio to See the Main Board, and Back Display Board Too.

Step 2: Locate the Ht9170d Chip on the Main Board, Near to Conecctor to Display Board

Step 3: Locate the Mic Conector Exclusive Pin 8 and Install a Wire From This Pin to Ht9170d Chip

Step 4: Install One End of the 2,2uf Electrolitic Capacitor on Pin # 2 Ht9170d Chip (vn Pin) and Another Capacitor End to Wire From the Pin 8 of the Mic Connector

Step 5: The Mod Is Done!, Now You KT8900 Have a Audio Signal From the Discriminator on the Pin #8 (mic Connector)

Reesamble your radio and make wires to your PC Sound card

The signal is clean and strong to your audio input on the sound card

Enjoy! 73




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I have a it 8900r old style. Can you tell me the pin out on the microphone 8 pin plug?

So this Provides a Discriminator Output to a PC or Packet Controller..

Is there a way to do this is Reverse i.e Inject a 9k6 Data into the Radio for say Digital Modes using MMDVM for example ?

Still working on that one. Analyzing the 9k6 waveform and determining if the reactance modulator will take the waveform and try to pre-emphasize the signal or cause it to roll off.