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

TI2BOX

Comments

[corrie-zs1cq]

Good Day
My VFO stopped working I cannot put a frequency in it starts but as soon as I put the last digget it go's back to =34.000

[WRNM460]

Will this mod work on a QYT KT-8900D…?

[jonglauser]

Even easier mod found! Just place a solder bridge as shown in the attached picture. The audio signal is already right there next to pin 8 but gets blocked by a chip, a Carrier Operated Switch I assume. the bridge bypasses the chip and dumps the audio signal from the input to the output and out onto the RJ-45 jack pin 8.

[twomilecookie]

Do you happen to know what the two pin component off of pin 7 on the RJ45 with the 'A' on it is?
I'm assuming a diode?
I'm not getting 8V at the jack, and this component has a hole in it, wondering if this may be at fault

[jonglauser]

I don't know what the part is, but diode is a good guess! Looks like it exploded, no other damage?

[twomilecookie]

Nothing visible. But no 8V is only part of the problem, also not getting any audio from the mic. That's next weekends task
:/

[ShaanWocker]

Thanks, once I have made the bridge which cable would I use to connect this to the sound card and where are you connecting it on the radio?
Also does this mod affect the normal use of the radio when not connected to the PC? (the open squelch)

[jonglauser]

Build a cable with an rj-45 on one end and whatever you need on the other end. That depends on how need to integrate. It doesn't affect normal use with the stock microphone. It would affect use if your microphone has channel up/down buttons and no keypad.

[PeterK191]

U should use pin3 in stead of pin 2 of the HT9170D. Then it is working fine.

[YavolF]

any luck doing a similar for the input? For doing the other side of MMDVM things.

[Skcscuba]

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

[rfeigenblatt]

pls check this website http://www.miklor.com/ 73!

[RobertA9]

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 ?

[optiontrader53]

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.