Review – BTech AMP-25 series for Analog & DMR

by John ‘Miklor’
K3NXU

The  AMP-25  series  VHF / UHF Amplifiers

The recently announced BTech Digital and Analog amplifier series puts a whole new spin on mobile operation. It performs more like a mobile than it does a power amp. The D series are true TDMA Tier2 DMR amplifiers.

Note: This review was done using an Anytone D868UV on both DMR and analog.

In the Box
Included with the 40W Mobile Amp are:
–  Mounting Bracket
–  3′  Interface Control Cable (Kenwood K1 connectors)
–  3′  RF connect cable (SMA-M to SMA-F)
–  Microphone and Hanger
–  All necessary mounting hardware
–  User Guide

General Description
–  UHF or VHF Power Amplifier
–  2-6W  >  20-40W  Output

                         Modes of operation include:

V25  U25	V25D   U25D
Analog (FM) C4FM (Fusion) P25  (Phase 1) NXDN IDAS dPMR MPT1327	>  DMR Tier II (TDMA)  >  P25  (Phase 2) Analog (FM) C4FM (Fusion) P25  (Phase 1) NXDN IDAS dPMR MPT1327

A Different type of Mobile Amplifier

I found these to be much more than a typical power amplifier. Although they can function as a simple ‘In and Out’ power amp, this is about as close to a full mobile as you can get. Although the driving force was my DMR handheld sitting in my cup holder, the transmit audio was that of the included hand microphone and the receiver audio out was coming through the built in speaker driven by a four watt audio amplifier.

Transmit Power

I tested the power on two different models. The VHF V25 (non TDMA) and the U25D for UHF DMR.  The power was tested using the analog side of both into a calibrated Bird Termaline wattmeter. The maximum current drain from my 13.6V 30A power supply was just under 6A. This is low enough for the amp to be powered by the 10A accessory jack in your vehicle.

Enclosure

The basic frame measures 4.6″W x 1.3″H x 5.5″D (excluding the SO-239) and weighs in at 26oz.  I was curious to see the internal layout of the amp and to no surprise, there was a 5/8″ finned heat sink spanning the entire length and width of the case along with air vent along the back of the enclosure.

Operating Modes

These are single band amplifiers.
V25(D) = VHF 136-174MHz
U25(D) = UHF 400-480MHz.

Note: The V25D and U25D were designed to include DMR Tier II (TDMA) and P25 Phase 2 along with all other modes. Their operation varies slightly.

V25  /  U25
To operate VHF through the UHF (U25) amplifier, or UHF through the VHF (V25) amplifier, simply power off the amplifier. This will allow you to run straight through directly to the antenna without power amplification on that band.

V25D / U25D
These amplifiers will only operate within their specified VHF or UHF range. This is due to the circuit switching design of DMR Tier II and P25 Phase 2.

Hook Up

The simplest configuration is using the included RF cable to attach the radio to the amp. You could add a Spkr/Micr to the handheld, but you would still be bypassing some of the best features.

I use the two included cables. The 3′ RF cable to attach the radio to the amp, and the control cable. This allows me to use the full size hand microphone as well as connecting the four watt audio amp powering the speaker. The power included power cable is compatible with handhelds using the standard two pin Kenwood style connector, such as an MD380, D868, GD77, UV5R, F8HP, UV82, etc.

I use an Anytone D868 on DMR as well as analog with the hookup diagrammed below. Depending on your radios antenna jack, you may need to pickup an SMA-M to SMA-M adapter.

 

Convenience

All channel selection and volume adjustments are done using the handheld. No duplicate programming or code plugs are necessary. Whatever is in my handheld is what I operate in the mobile

Operating my handheld in the low power position, I still get 22W out on UHF and my handheld’s battery life remains excellent, but high power gives me a solid 39W.

Conclusion

I was glad to see someone finally develop what is a full featured mobile amplifier capable of  DMR as well as all other modes including C4FM and D-Star that is small enough to mount in the car, boat, and on top of your computer. This amplifier is Part 90 certified and definitely worth considering.

Available from Amazon:    V25     V25D     U25     U25D
and     

VHF /UHF
Digital / Analog
Mobile Power Amplifiers

 

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

by John ‘Miklor’

APRS-K2
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 terminated 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, APRS.fi, 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

Includes:
APRS-K2 Cable
Reverse Connector Adapter
Quick Start Guide

Conclusion:
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
http://www.miklor.com

Review – BTech UV-5X3 TriBand Handheld

by John ‘Miklor‘

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UV-5X3
Although the case design is familiar, the radio inside is not.  BTech has recently introduced the new UV-5X3 to the US Ham Radio market.  This radio is a true triband transceiver with internal filters specifically configured for triband operation.The firmware in this radio has been reworked to include several new features not found in similar appearing radios.
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In the Box
Included with the radio are the:
–  1500mAh Li-Ion Battery **
–  85 page User Guide – English
–  Charger base & AC adapter
–  Hand strap
–  Belt clip
–  PTT Earpiece / Microphone
–  Antenna (1) – VHF / UHF  6  5/8″ (16.9cm)   A-V85
–  Antenna (2) –  220 MHz    6  3/4″ (17.4cm)
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** This is the identical battery that is commonly mislabeled as 1800mAh on some handhelds.

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Tri-Band – VHF  220  UHF
The UV-5X3 was specifically designed as a Tri-Band transceiver.  The internal filtering allows not only the traditional VHF and UHF frequencies, but also includes the 222-225 MHz Ham band for the US.

.   Case Design
The UV-5X3 has the traditional case design, which allows me to use my high capacity  BL-5L  3800mAh battery with no alteration to the base. Accessories such as my mobile battery eliminator, Spkr/Micr, etc. are fully compatible.
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Transmitter
The frequency range is VHF 130-176 / 222-225 / UHF 400-480 MHz, supporting both Wide and Narrowband with 2.5kHz steps.The radio’s filtering scheme allows for full power on all bands. My OTA audio reports have been clean with clear with mellow audio.  Power levels are respectable using a Bird VHF/UHF Termaline.

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UV-5X3 146 MHz 224 MHz 446 MHz High 5.2 4.2 4.6 Low 1.7 1.6 1.6

     
DTMF / IRLP Access
Something new also appearing on this model is a DTMF gain adjustment, allowing me to adjust the DTMF audio to the transmitter to a comfortable level for both repeater control and IRLP access.

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Tone Burst
If you are in a area that requires tone burst for repeater or network access, the 1000Hz, 1450Hz, 1750Hz, and 2000Hz burst are accessible by pressing the PTT along with one of the four pre-assigned keypad keys.

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Receiver
The receiver sensitivity is excellent, and the audio quality is clear, loud, and undistorted. Along with the 3 TX/RX bands, the receiver also includes the traditional commercial FM radio band. (65MHz-108MHz)
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Tone Scanning – The receiver also has the ability to identify the tone of a repeater being transmitted by a received signal.

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Scan Add / Delete
This feature gives me the ability to add / delete channels from the scanning list using the keypad. No longer a software only function. The more I can do from the keypad, the better I like it.

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Scanning
A Long Press of the [*SCN] button will start the scanning process.Channel Mode – When scanning with the Display Sync set to ON, the upper and lower display will scan together. This is explained below under Display Synchronization.Frequency Mode – When entering Scan, the image below will appear on the screen. Enter the first 3 digits set the range start, the second 3 digits sets the stop.
Example: Entering   146 : 146
Start  the scan range at  146.000
Ends the scan range at  146.999

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Antenna
I found two antennas included with the radio. One was the standard upgraded A-V85 antenna, and a slightly longer one for the 220MHz band.
Antenna (1) – VHF / UHF  6  5/4″ (16.9cm)   A-V85
Antenna (2) –  220 MHz    6  3/4″ (17.4cm)
The separate antenna specifically tuned for 220 MHz is a great addition. The SWR shows 1.3 which is excellent. No compromise. I labeled my 220 antenna, as they are very close in appearance.

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Display
The radio has a tri-color display, allowing the color options of the blue, orange and purple.  The LCD can be formatted in either of three formats. Choices are Frequency, Channel number, or up to 6 Alpha Characters.Display Synchronization
The UV-5X3 supports display syncing, which gives ability to track both the upper and lower LCD. I keep mine set to display the channel name in display A, and the frequency in display B. When you change the channel, both the upper and lower displays move together..
Programming
Manual programming is pretty straight forward once you enter a few channels. A programming guide can be found at Manual Programming with a Menu Definition summary available at Menu Definitions.

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Software  
The software support for the UV-5X3 can be found in the Latest Daily Build of CHIRP. There are a few new options that will be added to the 5X3 in the near future. One is the ability to Stun, Kill, Revive. This gives you the ability to disable your radio remotely.

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3rd Generation Chipset
The new chipset (RDA1846S and RDA5802N) provides reduced AGC switching noise and a low-IF digital audio processor for improved sound quality.

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Programming Cable
The programming cable requires a traditional two pin Baofeng / Kenwood style. There are several cable available. The generic cables may require special drivers, due to the use of cloned chips. For Plug and Play, a cable using an FTDI chip is recommended. Conclusion
The UV-5X3 firmware has obviously been reworked to include:
–  Tri-Band Support: VHF/1.25M/UHF
–  D-ANI  (Display incoming DTMF Tones)
–  Synchronized Displays
–  DTMF audio gain level adjustment
–  Add / Remove Channels from Scanning list via keypad (LCD Dot Indication)
–  On the Fly scanning by Frequency Range
–  4 Tone Burst options
–  Remote Stun, Kill, Revive

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It appears that BTech has once again managed to stay one step ahead of the curve. With the 220 MHz ham band operation back on the rise in the US, this radio hit the market at the right time.  Even if 220 isn’t popular in your area, the additional new features still give it an edge over the traditional dual band series.

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More Information:   Miklor.com,  BaofengTech,  CHIRP

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Build your Own Programming Cable

by John ‘Miklor’ K3NXU

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.

CP2102

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.

Take a small screw driver and pry the open the case from the back where the cable enters.

It should only be snapped together.
Unsolder the 3 wires connected to the board.  GND is Black, TX is Red, RX is White.
Solder the 3 wires to the corresponding terminals on the new board.

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.)

Driver

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.

 

Cosmetics

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: Miklor.com

Sainsonic GT-3, GT-3 Mark II additional notes

Thanks to a reader in Denmark I ran into a new, undocumented feature present in modern UV-5R varieties which have both a Band and an A/B button. The feature has been confirmed in the GT-3, GT-3 Mark II and the to-be-reviewed GT-3TP, but might be true for recent UV-5Rs also.

1750 Hz and 2100 Hz burst tones
In most parts of the world burst tones were once used to open up repeaters but abandoned in favor of CTCSS.  It’s one of the reasons why I don’t look into that feature too closely anymore; it became sort of irrelevant. Some European repeaters will still open up when a 1750 Hz tone is transmitted in order to stay compatible with older ham equipment.

Without notifying anyone (what’s new) Baofeng added the 2100 Hz burst tone to its bag of tricks. The problem is that this tone is not documented anywhere in the manual, and that they use the Band key to generate 2100 Hz instead of 1750 Hz. So, if you follow the manual, you’ll send 2100 Hz instead of 1750 Hz.

This is what you should do:

• Ignore the manual
• press PTT + A/B to generate 1750 Hz
• press PTT + Band to generate 2100 Hz.

I mailed this to John (Miklor.com) so it can be included in the documentation.

GT-3 antennas
The SMA thread on GT-3 antennas isn’t very precisely made. You might feel some resistance once every 180 degrees when screwing it on. It’s no biggie an will resolve itself after some use, but worth knowing.

UV-5R ‘reverse’ function oddity
When you have a repeater programmed in one of the memories and assuming you only programmed a CTCSS tone for TX, not RX, you would expect CTCSS to be irrelevant when listening reverse. That’s not the case; your Baofeng will ‘invent’ R-CTCSS on the fly. According to some hams this behavior can also be found on certain Kenwood models.