In an aviation environment where the ability to communicate affects so many operations, a good comms systems is vital.
The days when aircraft were served by clunky old comm sets with selector dials the size of 20 cent pieces are nearly gone now, with only a few stubborn remnants still in the air.
Modern radio transceivers are slimmer and easier to use when compared with the relics of yesteryear, and with the pace of cockpit technology increasing, comm sets are being forced into the integration era.
Many new cockpit systems now have a VHF transceiver integrated into the platform.
Flight decks and GPS systems often include a comm, which enables aircraft owners to scuttle one of their old sets in order to fit the new package in the stack.
In these instances, a stand-alone transceiver or NAV/comm will generally serve as the second, or even third, comm.
However, there are some GPS manufacturers that don’t offer integrated comms, but prefer to have built-in capability to link to a transceiver so frequencies can be selected in the GPS then loaded in the comm as the standby.
As a basic member of a modern integrated cockpit, it is essential that the right comm is in place; one that will work almost flawlessly with other avionics.
The last thing you need is to install all new bells and whistles only to find you are hampered by a comm set that will not play the game.
Honeywell Bendix King makes one basic comm-only transceiver but it has three varieties.
The KY 196A is a standard 760-channel 28-volt system, the 197A is a 14-volt version, and the 196B supports the 8.33kHz channel spacing required in Europe, giving you no less than 2,280 channels.
The KY 196/7A will store 11 frequencies at once: the active, the standby and nine in memory. Changing is via flip-flop or optional yoke-mounted switches.
This until also has an open mic trigger that automatically shuts down the set and flashes the display if the mic has been open for longer than two minutes.
That prevents accidental frequency jamming.
Bezel labels and knobs are backlit so they are easier to see at night.
A basic comm set without NAV capability.
BK’s TSO’d KX 125 is a very handy NAV/comm that is well laid out and logical to use.
The left hand side of the unit is reserved for the VHF transceiver and the right hand side for the NAV.
In the centre is an integrated digital CDI and OBS display.
There are independent selection knobs for the comm and NAV functions that are spaced well apart, which reduces the chances of you picking the wrong one and frequency changing for both is via their own flip-flop.
The VHF is the customary 760-channel set with a 35-second stuck-mic alert.
The NAV offers 200 VOR/LOC frequencies and the digital display can be set to either Radial or Bearing mode, with Radial giving you the standard TO/FROM flags and Bearing giving you a simple bearing to the station.
This is a handy unit that can also be interfaced with an autopilot, glideslope, DME and external CDI.
The KX 155 and KX 165 NAV/comm units are virtually identical, the only difference is that the 165 has a digital radial read-out and the lower-cost 155 doesn’t.
The display in both is a gas-discharge type with a photocell to automatically dim the digits.
Selection of the 760 comm and 200 NAV frequencies is via a three-stage knob and changing is via flip-flop.
Both units include a 40-channel glideslope receiver, but this can be optioned out.
Two stand-alone transceivers come from the Garmin stable: the Apollo SL30 NAV/comm and Apollo SL40 comm.
At first glance the SL30 is much like other units: 760 comm frequencies, 200 NAV frequencies, flip-flop changing.
Underneath, there are a couple of smart tricks it can perform.
Firstly it can decode the Morse identifier coming in from the station so you don’t have to worry about it; and secondly, it will also monitor the standby comm. or NAV frequencies.
This is very handy as it will enable you to dial up an ATIS, AERIS or AWIS on standby and listen without having to leave the active frequency.
Distance information can be displayed if the SL30 is connected to a remote DME or GPS, and it also interfaces with compatible autopilots.
The Apollo SL40 is a standard single VHF transceiver.
If that is all you want then this unit will suit you perfectly.
It has all the features of the comm side of the SL30, but it comes with an integrated two-place intercom.
In this respect it reflects its market well: uncomplicated GA, LSA and RAAus aircraft.
Icom are best known for their range of hand-held transceivers and scanners, but they also make a very respectable panel-mount comm set, the IC-A210.
While most manufacturers are using LCD or LED displays, Icom has fitted this unit with organic light-emitting diode (OLED) digits.
This technology has a reputation of being very clear to read with high contrast, and the display has an auto-dim function that adjusts for the optimum brightness in the available light.
The functionality includes the favoured flip-flop frequency switching and has an auto-stack feature, which remembers the last 10 frequencies used.
It can also accept numbers loaded into the standby from compatible GPS systems.
Another handy feature is a built-in DC-DC converter, which means you can install it in airside vehicles operating with 12-24 VDC electrical systems.
The IC-A210 has been made to slot into a radio stack space made vacant by most other common transceivers.
Bundaberg avionics manufacturer Microair claims their M760P comm is one of the smallest in the world.
As it fits neatly into a 57mm instrument hole and weighs 0.4kg, that is probably a fair claim.
Naturally, a unit as compact as this one is not going to have a lot of tricky bits, but it still manages to give frequencies down to 108Mhz, flip-flop functionality, an internal intercom and stuck-mic indication after 30 seconds.
The active and standby frequencies are displayed one on top of the other rather than side-by-side.
There is a fair bit of button-pushing required as you might expect, so a good read of the manual is recommended.
Not the most dazzling unit available, but is proving its worth in aircraft that have very limited panel space, and it seems to get the job done.
Narco has been making avionics since the Wright Flyer was a paper plane.
Their latest is the MK 12D+ TSO NAV/comm.
At 63mm high, this is a bulkier unit than its competitors (the next tallest of those sampled was 52mm), but that does have the effect of making for an uncluttered front panel.
As is customary, the comm is on the right and the NAV on the left.
To change the comm, you have the option of changing the active without it going through the standby first, or changing the standby then using the flip-flop to send it active.
Frequency selection is via knobs and a 10-channel memory is standard.
The display itself is the gas-discharge type and it has auto-dimming.
The NAV side is fairly conventional with the active on the left and standby on the right.
Changing frequencies is done as per the comm side.
When selected, a radial read-out FROM the station appears in the display where the standby would normally be.
A glideslope receiver is optional.
Narco also manufactures the MK 12D NAV/comm, which is a direct replacement for the Cessna RT 308 through to RT 328C series of radios.
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