Imbedded integration has nearly driven the stand-alone VHF transceiver to extinction. But for non-glass and simpler utilitarian panels, the traditional panel-mounted com radio lives on.
Even if your primary system is an integrated Garmin G3X or Dynon SkyView glass suite, a stand-alone com might make sense for emergency backup or for ground ops. A dedicated com can be convenient for fetching clearances and airport info without having to power up the entire panel.
In the March 2016 issue of KIT-PLANES, I looked at Experimental audio panels, and in this article I’ll move down the stack to the VHF transceiver. As you’ll see, how you choose might depend on panel real estate, whether or not you need VHF navigation capability, and EFIS interface.
If you’re building your project from scratch and have the panel on your bench, it’s time to scope out placement options for the radio’s control head. It used to be that com radios came in one form factor: A six-inch-wide radio stack-mounted chassis. Today, there are more options as some radios are two-piece systems, with a remote transceiver and a space-saving panel-mounted control head. This includes two models from UK-based Trig Avionics and German company Becker Avionics. There is also the Dynon SV-COM, designed to integrate with the SkyView suite. See the sidebar below for more on that glass integration.
The 6-watt Trig TY91 and higher-powered TY92 (which transmits 16 watts in a 28-volt electrical system) remote-mounted radios are designed with dedicated panel-mounted control heads wired to a remote transceiver.
PS Engineering’s PAR200A audio panel can serve as a controller/tuner for the radio, saving more space yet. The TY-series remote transceiver measures 5.5 inches long and stands 1.7 inches high, which should make it easy to mount in a variety of locations within the airframe.
If you don’t use PS Engineering’s PAR200A, Trig’s dedicated control head is designed to fit in a standard 2-inch instrument cutout or any area on the panel that can accommodate the 2.4-inch-wide by 1.8-inch-high chassis assembly. Total system weight is roughly one pound. The controller only occupies roughly 3 inches behind the panel, which offers flexible mounting options, especially for backup.
I like Trig’s choice of rugged interconnect hardware, which includes common D-sub wiring connectors. And when it comes to wiring, consider what you want for features based on coexisting equipment because like other models, the TY-series can bring significant audio capability to starkly equipped aircraft. There’s an integrated two-seat intercom, and for headset-free operation, the units come equipped with an integral speaker amplifier for direct connection to a cabin speaker. Trig says the TY91 can even be battery operated, making it an option for gliders and other aircraft without capable charging/electrical systems.
The controls on the radios are straightforward and simple, the way a com radio should be. There’s a volume and squelch knob, frequency tuning knob, and frequency transfer button at the bottom of the radio’s bezel. To the left of the LCD display, a frequency-monitoring button allows for monitoring the tuned standby frequency, while a memory button commands the nine-frequency memory storage bank. Visit www.trig-avionics.com.
With its Compact Line of products, Becker has a two-piece com radio: The model AR6201. It replaces the previous AR4201 series. Like the remote Trig TY91, the blue on white LCD-equipped AR6201 transmits 6 watts of power in a 12-volt electrical system. It also has a four-place voice-activated intercom, entertainment input capability, plus a 99-frequency storage bank, which will automatically store the last nine frequencies used.
In addition to the low voltage warning system, I like that a single Becker transceiver (that’s the RT6201 remote box) can support two control heads, which may be useful in tandem-seat aircraft, for example. It also has a scan mode, which monitors the chatter on the standby frequency. The AR6201 with 25 kHz frequency spacing sells for around $1,700 and is also available in 8.33 kHz spacing. Visit www.beckerusa.com.
Long discontinued—but still supported by Garmin—is the SL40 com and SL30 nav/com. These slim-line radios were designed by UPS-AT and Garmin acquired the product line when it bought the company. If you own one in need of repair, flat-rate factory repair cost for each is $550.
Garmin’s GTR225 com is a touch larger than the SL40 radio it replaces, but it brings modern amenities, including a database and onscreen facility nomenclature.
The GNC255A navcom is a full-function transceiver equipped with VOR, localizer, and glideslope receiver. It’s compatible with a wide variety of OBS indicators and EFISes.
Garmin’s GTR 200 is a non-certified com radio specifically designed for two-seat Experimentals and LSAs. It includes a built-in 2-place intercom.
The current production stand-alone com transceiver is the $1,995 GTR 225, and the $4,495 GNC 255A nav/com, which is equipped with localizer and glideslope receiver. Both of these radios borrow some technology found in Garmin’s GTN-series navigators, including the nav and com boards. Standard is a 10-watt com transmitter, and a version is available with a 16-watt transmitter.
If you’re wiring your kit’s avionics from scratch, you’ll appreciate the bezel-mounted USB port (no need to externally wire a USB port into the harness), which is used to update the system software and also the internal database. More on that in a minute.
If you operate in hot climates, Garmin has you covered with a cooling fan integrated into the radio’s chassis to draw forced-air cooling through the unit, plus inlets along the right side of the GTR/GNC chassis that allows air to flow through the unit. I once powered the unit for long periods of time in a packed RV-10 panel saddled to a test bench in a hot hangar, and the unit remained efficiently cool, while the cooling fan kicked on when appropriate.
The radios use traditional buttons and control knobs and an LCD display which doesn’t have a touchscreen. But that’s fine by me. Even on Garmin’s touchscreen GTN navigators, my fingers prefer tuning frequencies the old-fashioned way. Still, what immediately impressed me about Garmin’s redesigned radios is the straightforward feature set.
Garmin’s GTR/GNC-series VHF radios have a chassis-mounted cooling fan for better efficiency in tight stacks and for hot-climate ops.
In fact, the volume control, squelch control, and navigation radio IDENT control layout and functionality is borrowed from the Garmin GNS 430 and 530 navigators. Plus, frequency tuning is the same as it ever was—simply dial the frequency on the standby window on the right, and transfer it to the active window on the left, using the familiar flip-flop transfer button.
Garmin designed the GNC 255A to be compatible with a wide variety of indicators—perhaps one you already have installed. This includes Garmin’s GI-106A CDI, G500/600, Aspen Evolution PFD, the G3X, and third-party EFIS systems that have an ARINC 429 databus. For old-school panels, the GNC is also compatible with the BendixKing KN 62 and 64 series DMEs for displaying onscreen DME data, while pressing the OBS key displays the current OBS setting and a graphic CDI.
The interface doesn’t stop at the navigation receiver. It’s the com radio interfacing that makes the GNC/GTR units more advanced than any radio available for retrofit. It starts with an internal frequency database of airports and VOR stations. This data is provided for download on the Garmin web site and loaded to the unit with a thumb drive.
Pressing the function key enables the menu structure, where you can select the database feature to look up the airport name or station ID, much like you would in a GPS. There’s also a reverse lookup feature, which fetches the facility name associated with the frequency that the user manually tunes, using the database and a valid GPS position input. Further, when the radio has received data from an external GPS receiver or DME, it displays distance, speed, and time to station.
Once the frequencies are tuned, the monitor function allows for listening to the standby frequency without leaving the active frequency. For example, while approaching the airport, with the ATIS tuned into the standby, simply press the monitor button to copy the information.
Both units measure 1.65 x 6.25 by 10.4 inches and are designed for radio stack mounting.
Garmin also has a non-certified com radio with a feature set more suitable for two-seat LSA and Experimental aircraft—the GTR200. Priced at $1,359, the GTR200 is a descendant of the certified GTR225. It features a 10-watt transmitter, plus an integral two-place stereo intercom with pilot isolation function. This can save panel space and wiring effort in simple applications.
The GTR200 measures 1.35 inches tall by 6.25 inches wide. The display has a 45 side viewing angle and measures 3.0 x 0.48 inches, with a 200 x 33-pixel resolution.
A dedicated Monitor bezel key serves for listening to the standby frequency. Garmin took the interface one step further and incorporated its 3D audio function, which is found in its flagship audio panels. This provides special separation of the standby and active frequency in each ear when wearing a stereo headset. The 3D function spills over to the intercom function, too, separating the passenger chatter from one ear to the other.
Adding to the full functionality of the built-in intercom is automatic squelch and a pilot-controlled auxiliary input that is controlled with a dedicated bezel key (this can function as a control for music input or warning systems, for example). I like that the GTR200 is highly configurable, enabling one-touch access to the 121.5 emergency frequency, intercom music muting, plus the ability to recall saved frequencies.
A nifty feature is the on-screen volume graphic, which shows a rolling bar and the percentage of volume as you adjust it. Speaking of graphics, the GTR200 can display a textual name of the facility that is tuned in the active and standby windows. This data is fetched, via serial databus, from Garmin’s G3X integrated avionics and the late-model Garmin portable navigators.
The GTR200 makes use of a simple 37-pin connector, which stretches the chassis 9.3 inches deep. The entire system weighs just shy of two pounds, including mounting rack and connector hardware. Download a pilot’s guide at www.garmin.com.
With a solid reputation in the land mobile and amateur radio market, in addition to its popular and long-standing line of aviation portable transceivers, Icom makes the IC-A220 panel-mounted transceiver, which replaced the older A200 radio. Icom offers adapters for plug-and-play with the older radio.
Borrowing styling and technology from its land/mobile brethren, Icom’s A220 transceiver has a bright display and rugged user controls.
The two-pound A220 fits in a standard radio stack and measures 6.0 by 1.0 by 10.0 inches. It has an 8-watt transmitter and like its portable brethren, comes standard with generous features. This includes an advanced memory bank with programmable six-character channel name (it can store 200 channels), NOAA weather channel, plus one-touch 121.5 mHz emergency frequency access. The Dual Watch function allows you to monitor the active and standby channels simultaneously.
The A220 uses an OLED (organic LED) display, which enables a wide viewing angle and provides for high contrast and good sunlight readability. It also has a two-place voice-activated intercom. I like the ANL (automatic noise limiter), which helps to reduce noise in the receiver. Better yet is the dial and key lock—useful for careless fingers and in turbulence.
Using a serial data port, the A220 can fetch frequencies from an external GPS receiver or EFIS database. It’s compatible with Garmin and BendixKing serial outputs.
The A220 typically sells for about $1,299 with a custom wiring harness—a good value, in my view. Visit www.icomamerica.com.
With a factory and headquarters in South Africa and a facility in Torrance, California, MGL Avionics sells directly to the end user, in addition to OEMs. It offers two com radios—the V6 and V10.
The MGL V6 is a space-saver, has smart user features, and automatically adjusts mic gain for cleaner transmit modulation.
The 6-watt, LCD display-equipped, $1,095 V6 fits in a standard 2-inch round instrument cutout, weighs nine ounces, and requires roughly four inches of depth behind the panel, including its connector. A remote version—the V6R—is available for interface with the iEFIS, Odyssey/Voyager or the R2 control head. The radio accommodates two auxiliary inputs for aural alerts, plus a stereo music input, and has a four-place voice activated intercom.
MGL’s proprietary VOGAD (voice-operated gain-adjusting device) automatically adjusts the microphone gain as you speak, reducing background and engine noise in the carrier. There’s also a stuck microphone alert and a PC interface for loading frequencies.
The radio has two rotary knobs for volume and frequency tuning (which tunes in large steps when turned quickly, or in 25-kHz steps when tuned slowly). The V6 is compatible with the company’s iEFIS system and Dynon’s SkyView for frequency transfer.
The larger $1,050 V10 fits in a 31/8-inch instrument cutout and uses the same VOGAD technology as the V6. But unlike the V6, the V10 doesn’t have rotary knobs. Instead, pushbuttons adjust the frequency, while volume and squelch is adjusted with dedicated bezel keys, as is the frequency transfer and menu functions. If I had the choice, I might select the V6 with its intuitive and more traditional knobs over pushbuttons on the V10.
Both radios are available with custom wiring harnesses, including an RS-232 harness for interfacing with EFIS systems. See www.MGLavionics.com for more.
If you’re trying to save space in the radio stack, the $1,125 Val Avionics COM 2000 is worth a look. At 3.25 pounds, it stands barely an inch tall, but requires nine inches of depth behind the panel. The radio has a utilitarian feel and look, with a bright orange LED display with large characters.
The COM 2000 has an 8-watt transmitter, 15-frequency storage with user-defined alphanumeric channel identifiers, plus an RS-232 serial port for communicating with EFIS displays. The radio is plug compatible with the Garmin-AT SL40 radio, and VAL says it meets or exceeds TSO standards. VAL also makes the accompanying NAV 2000 VHF nav receiver, equipped with localizer and glideslope receiver, plus RS-232 databus for EFIS interface. It will also play on the VAL INS 429 electronic CDI.
Speaking of EFIS, the COM 2KR and NAV 2KR are remote-mounted com and nav transceivers that have limited compatibility with Dynon’s SkyView and Garmin’s G3X, and full capability with the Advanced AF-5000 series and Grand Rapids Horizon HXr system. For more, visit www.valavionics.com.
Consider the Wiring
As you can see, the market scan reveals a variety of model choices, many of which have advanced interface potential that will require additional wiring. If I had to pick, I would favor Garmin’s GTR200 for stand-alone com, GNC 255 for a full-up VHF navcom, and Trig’s TY91 for its price, space-saving footprint and compatibility with PS Engineering’s PAR200A audio system.
As I advised in the audio panel roundup, radio performance will only be as good as the interface wiring. This means careful routing of the coaxial cable from the radio to the antenna, while also using a quality antenna installed with the proper doubler plate for strength. For fabric aircraft, consider the size and quality of the ground plane and its effect on performance.
Last, consider antenna placement. While bottom-mounted antennas might offer better performance in flight, they may not offer the best range while on the ground, especially when the aircraft is tucked between hangars and buildings. For a nav/com, a separate navigation antenna is required, and could require signal splitters for receiving glideslope and VOR from the same antenna.
Carefully consider and accomplish this antenna work first, while the fuselage is open and accessible.