Chinese ham radio's, you either love them or you hate them. Regardless of how you feel about them, there's never been a cheaper time to get into the hobby. Low priced Chinese gear has allowed even those on the tightest budgets to get on the VHF and UHF bands.
One of the more complained about Chinese radio items are the hand mics. The Baofeng / Pofung handheld radio mics are well known for lousy transmit audio. It varies from "pillow over mic" to "mic in cardboard box" type sound. At roughly $5-$7 a piece, it's hard to ignore them despite their shortcomings. Fortunately, it's not hard to fix this issue. In this instructable I will show you how to fix the lousy transmit audio problem that plagues many of these mics.
What's required to complete this task..
You must be able to solder small components. We're not talking surface mount small but small nonetheless. You must have basic hand tools and the dexterity to use them on small parts. A soldering iron with a small tip is a must. A de-soldering iron is quite helpful but you can get the task done without it.
Step 1: Let's Dig In!
Start off by removing the philips head screws that hold the mic together. The mic shell should split open. When it opens, chances are you will have the PTT (Push To Talk) button fall out and maybe a plastic cover that covers an area for options the higher priced mics (which can also be plagued by the same lousy audio) have.
Don't fear, nothing broke. Everything has it's place in there and it's not hard to figure out. You will see a circuit board, remove the screws holding it in place.
Once the screws are out that hold the board, flip it over. You will see a little round silver cylinder with a black felt cover on it's end (pic 1). That is the actual mic element. You will need to remove it from the board without breaking it.
I suggest you first mark it with a black marker so you don't flip it around and wire it in wrong. Once marked then you need to liberate it from the board. A de-soldering iron is the tool of choice here but if you don't have one, don't despair.
With patience, you can get a soldering iron in so it heats both legs of the mic element allowing you to quickly yank it off. Once out, reheat the solder pads one at a time. Once the solder is melted, stick an awl or icepick in the hole and let it cool. The holes are small so it needs to be sharp. When the solder cools you should be left with a small hole in which to insert a wire in.
In pic 2 you see the mic element in my hand.
One of the main reasons these mics tend to sound awful is the placement of the mic element itself. The mic element sits away from the face of the mic in a little tunnel. This creates some weird sound cancellations and gives them their signature muffled sound. By moving the mic element so it's flush with the face of the mic, the problem is fixed.
Here's were we test your dexterity. If you have shaky hands, you'll need help here. You will need to solder some short (aprox 1") bare wires to the mic element. I used striped alarm wire but anything will work as long as its somewhat stiff and thin enough to fit in the holes in the pc board. Probably the best candidate here is a solid copper strand stripped out of some cat 5 cable. The long leads will allow you to reposition the mic element to where it really needs to be.
Be careful when doing this that you don't overheat the mic element, thus killing it or that you don't short the leads when soldering. They are very close together. If you busted your mic element, don't fret. I have salvaged replacements from discarded office telephone handsets. They work just as well.
Some of these early handmics don't have a hole at the mic element! The Chinese took quite a demoralizing tongue lashing for this on the radio forums and have since fixed the problem but it's still a bit on the tiny side.
In pic 1 you see the stock hole just above and to the right of the circuit board. It's a tiny slat. In pic two you see where I enlarged it using a drill bit that I just twisted by hand. Took all of a minute or two.
Take the mic element you just installed the extended leads on and get the leads threaded into the holes on the board. Don't forget to orient the mic element the same way it came out. Place the board back onto the mic shell and carefully push the leads in until the mic element moves up against the face of the mic. You may have to peek in from the side to see what you're doing. Once you have moved the mic element in as far as it will go, put in the screws that hold the board in place and you're ready to solder.
It's a cheap mic sold at a cheap price. One of the cost cutting measures the Chinese have employed is extremely thin board traces (the copper connections on the board). They peel and break easily. Should you bugger up the traces on the board were the mic connects, dont despair. Just follow it up a little bit to where it's not broken, lightly sand or scrap away the green coating on the board till you see copper and solder to that point. You can see in pic 1 where I had to do that.
Once soldered in, flip the mic over and look in the hole you previously opened up with the drill bit. You should see felt from the face of the little mic element. If it's off center, you can reposition it with a small screwdriver by pushing lightly on the leads under the circuit board. Be careful not to bend them and short them out.
Once soldered in you can test the mic before fully reassembling it. Test it. Make sure you have transmit and receive audio at the hand mic. No TX audio but radio keys, you may have shorted the mic element. No RX audio, make sure the speaker wires haven't broken off from all the movement while you worked on it. If all is well, reassemble.
Have fun with your great sounding $7 mic! It's always fun to catch the radio elite by surprise by asking for a signal report first and then telling them you're using a Baofeng with a handmic!