What You Need to Know Before Buying a DMR Radio

04 Aug. 2016   Information

Here are a few things you need to know before buying a DMR radio:

New or Used
For used DMR radios, it is buyer beware! Just remember that you will not be able to repair a non-working DMR radio unless you have the technical skills and necessary test equipment, and that test equipment can cost hundreds of times the cost of the radio.You typically get what you pay for; higher priced radios usually have more features, are better constructed and can handle more abuse than less expensive radios.

VHF, UHF or 900MHz
UHF is the most commonly used DMR band in the US and world wide, but because of military radar in some US areas, as well as different UHF public service frequency allocations in Canada, only VHF repeaters may be used in certain areas. In most areas, however, DMR activity may be found on VHF and UHF bands. As of April 2014, there are only two amateur 902-928MHz DMR digital repeaters in the US. If you are purchasing UHF equipment, make sure it covers the amateur band (420-450 MHz) from the factory. No one currently manufactures a multi-band DMR radio; there is little, if any, professional demand for such a radio and the amateur market is too small, at this time, to incentivize manufacturers to build one.

Programming Software
Some manufactures supply Programming software free. Motorola Solutions charges customers for a three year subscription (which covers all their models within a region) to their software and updates. DMR radios, because they are professional radios, typically do not allow keyboard programming. If a vendor charges for the programming software, do not ask another ham to bootleg a copy for you. If you have a legal copy, you may program radios for others, but you cannot legally distribute the software. Software piracy is illegal, and if caught, it could cost you greatly in the end.

Programming Cable
Some radios use standard USB cables for programming, while some may use special cables, please do be aware of this.

Number of Channels
Some radios have as few as 16 channels while others have as many as 1,000 channels. You will need a channel for each frequency, Color Code and Talk Group combination. You can easily use 3 to10 memory channels for each DMR repeater you program into your radio.

Display or Non-Display
Some radios have only a channel selector knob, while others have displays (monochrome or color) that will show Talk Group and ID information. Some displays only show channel number.

Visually Impaired Operators
Consideration must be given to the channel selection knob on the radios. Most of the non-display models have channel selection knobs that have fixed stops instead of 360° degree continuous rotation to allow the operator to find channel one. Some LCD display models also have fixed stops on the channel selector knob; these include some Hytera, CSI and HQT radios. Some models offer programmable voice announcements.

DTMF Keypad
Some radios have a 12-button DTMF keypad while others do not. Mototrbo™ repeaters support a proprietary auto patch feature. 

GPS
GPS is available on some models, but DMR does not support APRS (Amateur Packet Reporting System). On professional networks, one of the time slots is typically allocated for location reporting and is interconnected to server based dispatch applications. GPS will shorten battery life if it is enabled.

Bluetooth
Some higher end radios have Bluetooth built in for wireless headsets. I find this a great feature at work and home so I can listen without bothering others. Some radios with Bluetooth support data and programming via the Bluetooth wireless connection to the radio. Some models have Bluetooth adapters optionally available. Bluetooth will shorten battery life if enabled.

Analog
The Mototrbo™ SL75xx models don’t support analog FM. If analog FM is supported, it needs to be wideband FM because wideband FM is used on most legacy amateur repeaters. Current FCC rules require narrowband for most commercial/government services. For DMR radios from some manufacturers, this requires a programming entitlement key or a different version of the programming software.

Warning
Some DMR capable radios are available as analog only in their base configuration. The user may later add DMR for an additional license fee. This is because some manufacturers are discontinuing their analog non-DMR radios, while offering the DMR radios at a reduced MSRP if the digital mode is not enabled. On these radios, the customer later can upgrade the radio to operate DMR if their needs change, for an additional fee.

External Antenna on Portable
Not all portable radios support the connection of an external antenna, except for testing and alignment purposes. Using an adapter to connect an external antenna can place undue stress on the portable antenna connector which may result in premature equipment failure and expensive repair. If you are going to use an external antenna adapter, I recommend an adapter cable that uses RG-174 size cable to reduce stress on the radio’s connector. Some Mototrbo™ such as the XPR6000 series support an external microphone with an antenna mounted on the top.

Portable or Mobile
Digital Portable Radios are available in the 2-5 watt range; mobiles are available with a maximum of 10-45 watts. I recommend that your first DMR radio be a handheld type unless you live beyond the handheld coverage of your local DMR repeater. If you spend significant time in your vehicle commuting, you will find a mobile a good investment. Mobiles can also be used as a base station with the addition of an external power supply.

External Amplifier
Many external amplifiers will not work with DMR radios unless they are specifically designed to meet the fast switching requirements of TDMA on DMR. If you need more output power than a handheld DMR radio provides, purchase a mobile DMR radio.

Batteries and Chargers
Battery operated radios need a charger. Most radios come with at least a wall type charger. Some have desk chargers included or available for optional purchase. Some models have gang chargers available. You may want to consider a mobile charger or 12v battery adapter. The SL75x0 series can be charged using a USB cable, just like many cell phones. I always recommend having at least one spare battery and rotating them. You should follow manufacturer instructions for initial charging for maximum battery life. Remember to properly dispose of old batteries. Lithium ion batteries should not be thrown into the trash!

Warranty and Service Contracts 
If you buy an expensive new radio, you may want to consider the warranty and possibly purchase an extended service contact. Few amateurs have the technology or skills to work on these radios.

(Source: Abstracted from Amateur Radio Guide to Digital Mobile Radio (DMR) written by John S. Burningham, D.I.T.)