Baofeng UV-6 as an IRLP/Echolink/Allstarlink 2 meter or 440 Mhz (70CM) Radio
By: Ramon Gonzalez (KP4TR)
I recently picked up the Baofeng UV-6 dual band 2 meter and 70 cm radio for $35 free shipping from China. I was curious about this model due to the fact it had 2 meter capability which I was looking for a possible APRS or Allstarlink radio, and no DTMF buttons or LCD panel. Since it had no display panel and no DTMF buttons just like the Baofeng BF-888S, I believed it should be an easy radio to disassemble and modify for radio node use for IRLP, Echolink and Allstarlink.
As of today (4/19/2015) I could not find absolutely no diagrams, description, experimentation or nothing at all related to modifying this radio for possible radio node use on the web, so I created this page. There are plenty box opening videos and radio descriptions on YouTube, but not a soul who attempts to open it and look at the insides!
When I opened up the radio, this is what I found. The circuitry inside was clean and uncomplicated since there was no LCD panel or DTMF buttons to deal with, unlike the Baofeng UV-5R. The connections to the external mic and soldering pins were pretty much identical to the Baofeng BF-888S.
Looking for a possible COS (Carrier Open Squelch) source, I looked at the chip close to the mic connector as a suspicious audio chip. And yes, its the TDA2822, a low power audio amp. It is also used in the Baofeng UV-5R as seen in the ZL1NC page here.
With a voltage meter, I found pin 2 goes to 7.5V when squelch is opened. So using an NPN switching transistor is a safe way to not have to deal with this voltage when squelch opens. The IRLP board and the DMK Engineering URI FOB can handle these voltages directly. But using an NPN switching transistor is safer.
So here’s the wiring to the left. Remove the microphone element as it is not needed. For $36, you can afford to dedicate this radio to permanent radio node use! To the right is the wiring I used. The audio going to the soundcard mic input should use a 10K resistor, and the the audio going from the soundcard speaker to the radio mic input should have a 4.7K resistor. Volume set to the middle should give good level audio.
To route the cable to outside the radio, remove the plastic cover that covers the microphone connector. Cut the plastic tab out. This is the hole you can use to route the cable out.
This is how I wired the other side of the connector. It is wired to use the DMK Engineering URI FOB interface using a DB25 male connector. The wiring for the URI FOB is as follows:
1 – PTT
8 – COS
19 – Ground
20 Ground (PNP transistor emitter)
21 – Mic Input
22- Audio Left out
Once the wiring is done, we have a radio that will connect to Allstar. For IRLP, a different wiring is needed to a DB9 connector that connects to the IRLP board,, and to the soundcard connected to the IRLP computer. When I do this, Ill provide pictures.
The radio needs a 7.4V power supply. So to not have to get a battery eliminator for this radio, which I don’t think exists yet, I used the existing battery and the battery charger to create a battery eliminator and a 7.4V power supply. The battery was opened up and the battery inside removed. Solder the cables inside and the battery becomes a battery eliminator. I closed the case but no gluing needed. It snaps in place.
The battery charger will now be converted to a 12V to 7.4V power supply. I use a step-down transformer labeled “Chuangruifa”, readily available on EBay and Amazon.
Open the bottom of the Baofeng UV-6 charger and remove the circuit board inside. Place the step-down transformer in place, and solder the yellow and black wire to the connectors on the opposite side of the battery connector. I use Anderson powerpoles to expose the 12V wire on the other end.
Close the lid, and now we can connect the battery eliminator to the radio, and sit the radio in the new power supply.
I have been using my radio for the past month and it works flawlessly using the URI Fob.
Hope this article is of use! 73.