Posts Tagged ‘Baofeng GT-3’
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
– UHF or VHF Power Amplifier
– 2-6W > 20-40W Output
Modes of operation include:
|V25 U25||V25D U25D|
P25 (Phase 1)
| > DMR Tier II (TDMA)|
> P25 (Phase 2)
P25 (Phase 1)
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.
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.
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.
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.
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.
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.
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.
by John ‘Miklor’
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.
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.
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
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.
Too many toys, too little time.
John ‘Miklor’ K3NXU