I review the Motorola frequency-hopping spread-spectrum (FHSS) licence-free DTR410, DTR550, and DTR650 radios.
Transmissions with the DTR radios are very clear and they have about the best range possible with any VHF/UHF portable radio. (Like any VHF or UHF portable, they are basically line-of-sight, so distance evaluations are always subjective.)
To test the range, I turned one on, left it in the kitchen and then walked down the street with a second one in my pocket while I went to the nearest pub for a cold draft. (It has been almost 30 degrees C this past week!) When both are on, pushing the PTT causes a short ‘handshake’ to take place to make sure at least one other unit is in range. This is indicated by the “Nextel-like” tone. Once the tone ends about 1/2 second later, you can start talking. If the other radio is not in range, you will instead hear a loud beep. You don’t even need a second person to do range tests.
Basically, I was able to walk about 1 to 2 kilometres through this dense residential area. The signal had to penetrate all the large, wood-frame homes, mature elm trees and a large school, all within the line of sight. When I made it inside the pub, I lost the signal but walking out the front door regained it again. (Don’t forget the other radio was INSIDE my house.)
This was quite impressive, and exceeded any FRS/GMRS or business radio I have used in the same area by at least 1 city block.
The DTR-series radios are digital radios, which means there is about a 1/2 second delay in the transmission. It also means that there is no fuzzy transmission from the far edge of their working range; they are either 100% clear or they don’t transmit at all. When tested side-by-side with one of the best of the bubble-pack GMRS radios, the DTRs were much clearer.
The clarity is the same or better than any high-end business radio, and the mil-spec build quality and weatherproof design makes them expensive but easily worth it in my opinion if you are seeking this level of quality, reliability and readability.
Because they are a FHSS radio, there is no licencing required in either Canada or the U.S. They transmit on the 900 MHz band, which is shared with millions of cordless phones and other electronic devices but the Motorola only stays on one frequency for 90 milliseconds, and would not cause noticeable interference with anything else. One cannot eavesdrop on a conversation with consumer-level scanners either.
All Motorola accessories designed for the radios fit well. It is important to note that not all third-party accessories fit properly. There is very little clearance in the socket for mic/headset accessories, and one MUST use the two-prong Motorola plug that fits these tight sockets. There are two versions of two-prong plugs designed for Motorolas, so I would highly suggest that before you use a non-Motorola product, you test them first.
The reason is actually quite simple. The one version has SLIGHTLY shorter prongs than the other style. One CAN make them fit by some judicious trimming under the prongs with a razor knife, but it is better to get the proper plug on your accessories in the first place.
Accessories such as speaker mics and two-wire surveillance kits work fine and the clarity is great. It is important to note that one can adjust both the volume and microphone sensitivity of the internal mic and speaker AND external accessories attached to the radio separately.
If you are using them in windy conditions, it is a good idea to lower the mic sensitivity or you will pick up wind noise that sounds much like static, but isn’t. (This is easy to change … once I found out what setting to use. More on that in a moment.)
So, everything is great about these radios? Well … not quite.
At the time of this review, the support from Motorola and the user manuals needed work. The manuals have contradictory and missing information and it took DAYS of working with the radios in one hand and the manuals in the other to try to figure out how to program them.
Here are some examples. On page 2-17, it explains how one can change the volume of the ringer, speaker, keypad, alarm and talk-permit tone (“Nextel-like” beep to confirm another radio is in range.) The only problem is, there is no ability to adjust the volume of the talk confirmation tone on that generation of DTR410, 550 or 650. The talk-permit tone simply gets louder as the speaker volume is turned up, and contrary to the user manual, there is no way to turn it down independent of the speaker. EDIT: This was added to the generation 3 version of the DTR radio firmware. See subsequent post. It appears Motorola printed a feature in the manuals long before they were actually available on the radios.)
On page 2-18, it also explains how to adjust the microphone sensitivity to the ambient noise of the environment. In the first paragraph, it states that a LOW setting means the setting for low ambient noise areas and increases the sensitivity of the microphone to high for good clarity of sound. (On low, even a soft whisper comes across clear and understandable.)
In the very next paragraph, it contradicts itself, and says that setting the ambient noise setting to low is designed for HIGH ambient noise environments and DECREASES the sensitivity of the microphone. When I tested it in very windy conditions, and the first paragraph is correct; the second paragraph is wrong. If you are using them in a high noise environment, set the ambient noise setting to HIGH, and if the ambient noise is low, set it to LOW. When set to LOW, it increases the mic sensitivity so you can clearly hear a whisper. When set to HIGH, it decreases mic sensitivity so high ambient noises like wind and running machinery do not overwhelm the signal.
Motorola has free programming software for all three models, although for many years, the software was only available for the 410. It now works on all three: 410, 550, and 650. To program them by computer, you need a special programming cable that plugs into a serial port on your Windows computer. For computers that do not have a serial port, use a serial-to-USB adapter. The most problem-free adapters use what’s called an FTDI chip.)
One can program the radios manually without the programming software of course, but this takes a very careful reading of the manual and a long and laborious process. On my private “net” of DTR radios, I wanted them to have unique names so I purchased the mini-keypad to help program them with unique names. I didn’t want the screen to read “public group1” and the user to be listed on my contact list as “12345678910” so I used the mini-keypad to change the names and add some more text messages.
With the mini-keypad, I erased the default messages, added some new ones, changed the name of each radio into something that actually made sense, moved from the default channel 1 into a less-likely to be used channel and then added each of the other radios as a private group. Once you do all this programming on one, you then do it for all the rest. Once that is done, you then have to go into the programming menu (which takes holding down the “home” button while pushing the PTT 3 times, then pressing right bar button, down button, left bar button, holding down the “home” button and pressing the PTT 3 times again, to get into the programming menu) on one radio, selecting the name of the other radio and then when programming the ID, you select “read” and press the “home” button of the other radio 3 times and then the PTT, and this adds the other radio to the first one.
You then do this in turn with each radio you have so that every radio will recognize every other radio. Simple. It actually works great, but you can begin to see why this takes hours to do all this. (And why I spent so much time down the street in the pub drinking cold beer!)
That being said, one can simply unpack them, turn them on and use them without any fancy programming needed. They default to channel 1 and unit ID 1, and Motorola DTR radio will work with any other DTR radio right out of the box.
Currently, I am now working with the various “public group” and “private group” options, plus trying to calculate how many possible channel combinations there are. (The DTR radios don’t really use fixed “channels,” they are Motorola’s proprietary channel hopping algorithm.) There are 10 “channels” one can set their radio on, and 100 possible unit ID numbers. Each radio must be set to the same channel plus the same unit ID number to be heard by each other, but each unit ID number can be used only once. By my math, this means there are 955 unique combinations one can use.
So the bottom line is that they are great radios, but with a complicated user interface and a confusing manual. But once programmed, the battery life (lithium batteries) is incredible, the range is about the best you can get in any UHF radio and the clarity of the transmissions is as good as any other business radio on the market. If you listen to the comparison sound files on the Buytwowayradios.com website, you may notice a slight “digital” robotic sound to some of the words, but in actual use, I don’t notice anything like that. Every word is clear, and there are times I wish my cell phone had this same readability.