Posted on Leave a comment

Lethal Chinese Mains Adaptors

With every piece of Chinese electronics I obtain, mainly Baofeng radios, they come with a Europlug-type power adaptor, and a universal plug adaptor for the mains.

The charger units aren’t too bad, there’s a fair amount of isolation between the primary & secondary, and even though they’re very simple & cheap, I can’t see any immediate safety problems with them.

The plug adaptors, however, are a different matter. These things are utterly lethal!

Baofeng PSU
Baofeng PSU

Here’s the inside of the PSU. It’s just a very simple SMPS, giving an output of 10v 500mA. The fuse is actually a fusible resistor.

PCB Reverse
PCB Reverse

Here’s the back of the PCB with the SMPS control IC. I can’t find any English datasheets for this part unfortunately.

Universal Travel Adaptor
Universal Travel Adaptor

Here’s the dangerous adaptor. There’s no safety shield, so the live parts are exposed.

Internals
Internals

Here’s the adaptor split apart. The output contacts are on the left, and rely just on pressure to make contact with the brass screws on the mains input pins to provide power.
This is a very poor way to get a connection, a dirty or worn contact here would create a lot of heat if any significant power is pulled through, and could quite possibly result in a fire.

Not surprisingly, I bin these things as soon as I open the box, and charge all my radios with a 12v charging system.

Posted on Leave a comment

New Radio – Baofeng UV-82

Thanks to Lewis over at Distant Signal Radio, the bad influence he is on my bank balance ;), I’m the proud new owner of a new Baofeng. This time it’s the UV-82.

This radio is a little different from the other Baofengs I have. Here are the main differences:

  • Dual PTT – This one is going to take some getting used to 😉
  • Higher capacity battery pack
  • A more rugged, commercial feel

This radio has a different method of selecting the VFO mode – holding the menu key while the unit is powered on. This is a little awkward, but since I only usually use my local repeaters when I’m mobile, it’s not much of an issue.

UV-82
UV-82

Here’s the radio itself, it has a much more commercial feel to it than the UV-5Rs, and it’s slightly bigger. Mainly due to the use of a larger standard battery & larger loudspeaker.

Spec Label
Spec Label

Back of the unit with the spec label. As per usual Baofeng are a bit conservative with the power ratings, more to come on that below.

Battery Pack
Battery Pack

Here’s the battery pack, a 2-cell lithium-polymer unit. This has a bigger capacity than the standard UV-5R battery, at 2800mAh.

Here are the power settings as measured by my GY-561. Frequencies used are 145.500 & 433.500


 

VHF High: 7W
VHF Low: 2.5W


UHF High: 6W
UHF Low: 3.1W


 

Posted on Leave a comment

Stock Baofeng Antenna Problems

Recently I’ve noticed my usual mobile rig, the Baofeng UV-5R, has had very poor receive, and non-existent transmit.

I did a power test on the radio, and confirmed it was still outputting it’s rated RF power. Trying another antenna proved that the radio was fine.

Time to tear down the antenna & see if it can be fixed!

Stock Antenna
Stock Antenna

Here’s the antenna, just the factory rubber duckie. As with all these antennas, they’re a compromise between size & their efficiency.

Naked Antenna!
Naked Antenna!

Giving a gentle pull to the antenna sheath while it’s attached to the radio allows it to come apart. The quality actually doesn’t look to bad. It’s very similar in construction to my Diamond X-30, just on a much smaller scale.

At the bottom of the antenna is the matching network, an inductor & ceramic disc capacitor. Here lies the problem with this antenna.

Dry Joint
Dry Joint

Here where the capacitor joins onto the feedpoint from the SMA connector, the solder joint has come away. This was a very poor joint to start with, and the solder hadn’t wetted the capacitor lead at all

After cleaning the joint, and applying some flux, a new joint was easily made with some Real Solder.

Repaired Joint
Repaired Joint

Here’s the joint freshly repaired, the antenna is now back to full working order. It even seems to work better than the others I have 🙂