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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

TI2BOX

<p>I have a newer model (KT-8900D) which has a 20-pin chip, HM9170. Pin-1 is opposite of your picture and there are some similar features of the main board and the front face board. I have not been able to find information on this IC to implement this mod on the newer model radio. Any help out there? Thanks.</p><p>I also have a KT-7900D that might require this mod, also.</p>
Hi KC0TA I have only a KT8900 to make test, if HM9170 as inverted position on the board in your radio, look for the pin #2 on your chip and follow my instructable to install a electrolytic capacitor<br><br>73, TI2BOX
<p>I'm wondering about the compatibility of the HM9170 and the HT9170D. The HM9170 is a 20-pin chip while the HT9170D is an 18-pin chip. I just can't find any data on the HM9170 to verify the pinouts of the device. The KT-8900D has a 2-tone and 5-tone decoder function which may explain the different chip (HM9170 with 20 pins) in my radio. It would certainly help if I could locate a schematic of the radio and/or data sheet for the HM9170 chip. Any ideas on getting a radio schematic?</p><p>73, KC0TA</p>
<p>I see, really I not have any idea about this datasheet, I think you will find the discrimnator signal easy with a oscilloscope test each pin of the HM9170 when the radio is on RX mode</p><p>73, TI2BOX</p>
<p>Yes, I agree with analyzing with oscilloscope. I was hoping to make this simple with the aid of a data sheet but, as usual, things I do are rarely ever simple. Thanks.<br><br>73, Mike, KC0TA</p>

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