Review – BTech APRS-K2 Cable (TRRS/APRS)

by John ‘Miklor’

It’s long overdue, but there’s finally a TRRS/APRS cable available for radios using a standard Kenwood style K2 connector.

I’ve been wanting to get involved with APRS for a while now, and this made it extremely easy.

APRS-K2 interface cable
The APRS-K2 cable allows you to interface your handheld transceiver with your existing mobile device, including. iPhone, iPad, and Android.

One end of the cable uses the Kenwood style K2 connector, while the opposite end is aprs-xover-25terminated with a TRRS connector. Also included with the APRS-K2 is a Reverse Adapter to insure compatibility with all devices. This adapter allows cable to connect to earlier 3.5MM TRRS standards, such as Nokia.

App Driven
The APRS-K2 cable uses a virtual TNC found in several apps, such as APRSDroid,, and Pocket Packet. Plug in the cable, turn on the VOX, and you’re pretty much set to go.

Product Description
BTECH APRS-K2 TRRS / APRS Cable A simple way to start using APRS by using devices you already own. The BTECH APRS-K2 Cable will quickly connect your radio to APRS by using virtual TNC (app driven) on your tablet or device. The APRS-K2 cable is built with a custom circuit board that will automatically adjust the audio for clear packet transmissions with minimal adjustment; along with protecting your devices from strong over modulated signals.

Along with allowing APRS functionality the APRS-K2 cable can provide a simple interface gateway to allow several features to your radio!

Easily record radio conversations:
By connecting the APRS-K2 cable between your radio and any recording (line-in) device.

Use the APRS-K2 cable as a Mic In Connector:
Set up VOX on your radio to accept any form of incoming audio – such as a Push-to-talk application on a Phone – or a Line-out application from your computer.

Use the APRS-K2 cable to push transmissions over a speaker system:
Easily play audio over a intercom or speaker system from your handheld.

With a backup radio and your own ingenuity, the APRS-K2 cable can serve as an interface for a variety of applications for any amateur. Compatible with Kenwood K2 Accessory Slot Radios (such as BaoFeng, BTECH, Wouxun, TYT) Compatible with all phones, tablets, and computers with 3.5MM Audio In/Out Ports

APRS-K2 Cable
Reverse Connector Adapter
Quick Start Guide


The cable comes with a simple one page instruction sheet which should have you up and running in about 10 minutes after the appropriate app is loaded.
–  Plug in the cable
–  Set your handhelds volume control
–  Turn on the VOX
–  Set your handheld to 144.390 (US)
–  Activate the app

That’s all it takes. If you’ve been considering building an APRS cable, you might find this an easy Plus and Play alternative.

The APRS-K2 can be ordered from   Amazon, or if outside the US, you can go to their website and contact them directly.   Baofeng Tech

Too many toys, too little time.
John ‘Miklor’   K3NXU

Build your Own Programming Cable

by John ‘Miklor’ K3NXU

CP2102j[1] Frustrated with that generic programming cable?
This $2 solution might just be your ticket to sanity.

Let’s See…

You purchased a radio and programming cable, loaded the software, and that’s as far as you’ve gotten. You’re fighting with error messages:
– Radio did not respond
– Could not open COM port
– Run Time Error
and Windows (TM) 10 keeps changing your drivers.

Now you do what many owners do. Put the radio in the drawer to be worked on later. This is like buying a roll-away treadmill and putting it in the closet until the next time you want to exercise. (NOT going to happen)

But wait, yours has the company name and logo right on the cable.
– It doesn’t matter. Keep reading.

There are a few options available, such as an FTDI cable. It’s truly Plug ‘n Play, and costs about $20.

But here’s a project that just might solve the issue for around $2. All you need is a small flat blade screwdriver, a soldering pencil, and a CP2102 board.


The CP2102 is a USB to TTL UART chip. What?
Long story short… It’s the same thing that’s in your current cable now, except these work.

CP2102 boards can be found on eBay for around $2 and on Amazon.

Here’s How

Let’s start with that original cable.CP2102j[1]

Take a small screw driver and pry the open the case from the back where the cable enters.
It should only be snapped together.CP2102b
Unsolder the 3 wires connected to the board.  GND is Black, TX is Red, RX is White.CP2102c
Solder the 3 wires to the corresponding terminals on the new board.CP2102g

Note 1:
Some boards may have the TxD and RxD reversed. If it doesn’t work the first time, reverse the two wires. No damage has been done.

Note 2: Some boards have pins on the back requiring small connectors. You can either remove the pins, solder to them, or use the connectors. (Whatever floats your boat.)


When you insert the new board into the USB port, give Windows a chance to find and load the new driver. Should take about 30 seconds. When it says Driver Found, you’re done.

If the driver is labeled CH340 instead of CP210x in Device Manager, that’s not a problem. Both chips are designed to do the same thing.

But I don’t have a Cable

If you don’t have a generic cable, you can use 2.5 and 3.5mm stereo jacks. Here are the pin outs, and what Jim’s (KC9HI) cable looks like.
CP2102jim CP2102o



If you are adventurous, try retrofitting the new board inside the original plastic housing. This will require a Dremel tool, X-Acto knife, Glue, and some patience, but it can be done.

If the board only has 5 terminals instead of 6, it’s not an issue. You only need GND, TX and RX.

Some come protected with a piece of clear heat shrink over the board so you can see the cool blinking lights.

Note 3: If you are trying to retrofit the board inside an existing shell, the red board below is a bit shorter and easier to fit.          Amazon       eBay
For about a dollar or so more, you can find the same boards in a metal case.

What’s the Advantage

– First and Foremost, it works. Take the radio out of the drawer, program it and have some fun.

– Next, it only cost around $2 to save the generic cable from the trash.

– Very Important – Bragging Rights. Now, when you go to a club meeting and someone says they can’t get their cable to work, tell them they can build their own, just as you did.

I hope you had fun with this project. It’s super simple and very rewarding. I’ve made several and never had a failure. Say goodbye to driver issues.

My thanks to Jim KC9HI for his input on this project

More Information:

First impressions Wouxun KG-UV950PL

By David G3ZPF (website)

Those of you who are RSGB members will no doubt have seen the review of the Wouxun KV-UG950P quad band FM mobile rig a couple of months back. It covered 70cm/2/6/10m, as per a number of other quad band mobile rigs. What may have passed un-noticed though was a mention on the Martin Lynch website of a different version of that rig (suffix PL), covering 70cm/2/6/4m.

Not expected to arrive until late October. I initially thought this would be a 3rd-party rework, swapping 10m for 4m but it turns out that MLS commissioned a custom version to be made in the Wouxun factory. The replacement of 10m by 4m seemed a far better ‘fit’ for the UK market to me so I decided to pre-order one & it arrived yesterday afternoon. I was wary buying ‘sight unseen’ but I’m really pleased with it.

KG-UV950PLFirst impressions are very good. A few of the menu options (those which won’t be used by amateurs) indicate its ancestry in the professional PMR market which is probably why it is ‘built like a brick privy’. The whole case is basically one big heatsink. On 4/6/2m it will run 50w, reducing to 40w on 70cm. The front panel is removable (separation cable supplied) and is able to be attached either horizontally, or angled slightly up or down. In addition to the internal speaker there is a speaker built into the mic (for very noisy environments) and the option for separate external speakers for each ‘side’ of the rig. It is effectively two rigs in one. A mobile mounting bracket is supplied too.

I fired it up on 4m and a local came straight back with “you’ve got a new rig. Sounds much better than the PMR box”, which was encouraging. The supplied manual is actually for the version with 10m at the moment, but read 70MHz for 28MHz and you’ll be fine. The display has several colour options. As supplied it was set up to use a different colour for receive, busy channel, and transmit, which drove me nuts so I changed it to green for everything. Initially I found myself drowning in options/settings but an hour or so later I’d got it the way I liked it. A real surprise was finding it covered the FM broadcast band (rx only) which I didn’t see in the spec & discovered by accident.

The manual is functional, rather than polished, but all the info is in there. The menu tree is as extensive as similar rigs by the other makers & will take a while to get used to. A dealer persuading a maker to produce a customized batch of a rig is a new development in the amateur market. If the USA had not failed in their recent attempt to get a 70MHz allocation this custom rig may well have been the regular one. The build quality indicates some of the Chinese makers are getting their quality control act together….although some/all of the ‘big three’ allegedly have some Chinese builders.

You’ll need to be careful choosing duplexers with this rig as most swap HF/UHF at around 65 MHz, but there is a COMET one that swaps at 95MHz. The 600w rating is ‘ambitious’ but good enough for this rig. Ive not detected any noticeable power loss on throughput, or leaking from one port to the other. I have an x200 for 2/70, and a separate 4m vet. Not using 6m yet as I have the ts590 for that.

I’m still pleased with the Wouxun (pronounced ooh-shun, according to Martin Lynch & sons). Receiver is much better than the old PMR set I had on 4m. I’m told its far better than the Anytone 4m FM rig too, and I reckon slightly ahead of the IC7100 on 4m. I’ve played with the programming software, which is very basic. Its a good job it is free. I’d describe it as an ‘early alpha’ release.

In short
It works but …. there seems to be a slight ‘latency’ switching from transmit to receive, and back, which may be an issue for some. I think this is down to the switching delay (100mS) allowed for ctss and dsc tones which you can increase, but not turn off completely. Whatever the reason it is more noticeable on 70MHz band for some reason.

Volume controls are not pots, but stepped digital increases.

David G3ZPF

Wouxun KG-UV950PL – Quad Band 4/6/2/70

Interesting news Tim G4VXE picked up is that both Wouxun and TYT will be offering a version of their quad-band mobiles which will include 70MHz (source: The Wouxun KG-UV950PL is already available and listed on the website of Martin Lynch & Sons Ltd (link). The price is £249.99 (including 20% VAT). According to the specs the output on 4 meters is 50 Watts, FM only.KG-UV950PL

Fixing the “Wouxun Memory Loss” bug

Remember the various posts about Wouxun handhelds losing memory contents? Although the chance of encountering this problem seems to be remote, it does happen. A small component (a 24C64 serial memory IC) can give up in time.

The good news: it can be repaired/replaced at almost no cost (about 60 cents). The bad news: you need to be comfortable with working on small components and must have the tools to do it. If you don’t, have it done by someone with more experience.

Wouxun Memory

The complete repair guide can be read in detail on Mike Mercury’s, which is the website of Tim N8NQH.

Link to a Chinese eBay seller (10 pieces for $2.38):