Icarus Instruments
EXTenna Switch
The Icarus Instruments EXTenna Switch is a small device installed in an aircraft that permits an existing VHF comm antenna to be used with any handheld VHF radio. This greatly extends the range and readability of these battery powered handheld radios. The normal handheld radio’s “rubber ducky” antenna has very limited range when used inside an aircraft cockpit.
The EXTenna Switch eliminates the need to install a dedicated backup VHF comm antenna which is both expensive and adds drag to the airframe.
Installation - The EXTenna Switch is mounted on the aircraft’s instrument panel. It has two BNC connectors on the back side. The one labelled TX connects to an existing VHF comm radio’s antenna connector (normally comm 2) using a BNC jumper cable (not supplied). The one labelled ANT connects to the VHF comm antenna serving the same radio. The existing antenna cable can be rerouted to the EXTenna Switch, or an extension cable can be used if necessary. There is a jack on the front for connecting the supplied cable to the handheld radio’s BNC RF jack.
How To Use - The default condition is that the comm radio is directly connected to the existing comm antenna through the EXTenna Switch. When the pilot needs to use the handheld radio, the supplied cable’s 3.5mm connector its plugged into the jack on the EXTenna Switch. This disconnects the normal comm radio from its antenna and connects it to the handheld radio.
Installation Approval Process - The EXTenna Switch is a small, non-powered, passive device that weighs two ounces. Installation can be accomplished by using the Minor Alteration FAA guidance. The EXTenna Switch is designed to be installed by an FAA licensed facility except for Experimental aircraft.
The panel mounted EXTSW-1 is installed in a 1.75” W x 1.3” H vacant space on the panel using the supplied two screws. A precision steel drilling template is provided to ensure accurate placement of three small holes. Besides the two mounting holes, a third hole is needed for the antenna jack. An attractive label is provided to identify the jack’s purpose and the product name.
EXTPLATE is an optional accessory for the EXTenna switch that allows the switch to be mounted in an existing 2.25” instrument cutout. No panel drilling is required for this accessory.
Situations where the EXTenna Switch would be useful:
- Aircraft electrical system experiences a complete failure, rendering all comm radios unusable. Or an aircraft running on the “essentials bus” finally exhausts the aircraft’s battery. A handheld radio connected to an existing external comm antenna via the EXTenna Switch would then be used to establish ATC communications.
- Aircraft with only one VHF comm radio experiences a radio failure. The EXTenna Switch enables the immediate use of a handheld radio to contact ATC.
- Aircraft’s intercom system fails and pilot headsets are unable to connect to any VHF comm radio. A handheld radio can be used by utilizing the EXTenna switch to communicate with ATC.
- Pilot is told to call Clearance Delivery in 20 minutes and to not start the engines. A handheld radio using the EXTenna switch can be used to contact Clearance Delivery without having to start the engines or power up the ship’s main bus to enable the main radios. Pilots can also monitor local frequencies using the handheld to better understand the situation.
- Aircraft experiences a headset failure, and no spare is available. A handheld radio can be used to contact ATC by using the EXTenna Switch.
- Push to talk switch fails to trigger any radio. The pilot can then use a handheld radio using the EXTenna switch to contact ATC.
