There are several ELT on the market for the experimental aircrafts. For our composite plane, we must add a ground plane under the center antenna. That's somewhat of a hassle and most builders dread it - me included. There is an ELT (Ameri-King 451) claimed to have TSO approved antenna that does not require a ground plane. I downloaded their installation manual and found that its rather straight forward. It's installation procedures mirror other popular brands as well. It has a GPS hook up which will download every 5 seconds. In the event of an accident that warrants the activation of the ELT, the GPS location will be transmitted concurrently - reducing the search and rescue time from hours to minutes. The only concern I have is that this ELT uses its own battery power throughout its operational period (~5 years). Seems to me, that's quite a constant draw on a battery. Regardless, so far so good...until I found out more from customer reviews. According to the reviews, there were many complaints of early battery failures and poor repair support. I also found an article relating to employee complaints of poor quality parts being used for the ELT and that FAA was getting involved. Hmmm...
I finally decided to go with a different brand - the ACK-E04 instead. I checked around for competitive prices for the ELT and found they are pretty much the same from various sources. I decided to buy it from Aircraft Spruce which is only 6 miles from the Chino Airport. I purchased the complete installation kit. The ACK-E04 requires a ground plane, 12V power from the electrical system, a ground line and a RS232 for GPS input. It happens that Tim Andres has the same unit. That's even better, I can learn from him! 2 days after I purchased the ACK unit, I heard that FAA shut down the Ameri-King ELT product line. Talk about ducking the bullet.
The ACK-E04 consists of a main transmitter/battery, a remote control unit, a horn, and a whip antenna. I decided to mount the transmitter under the pilot seat, the control unit at the IP and the whip antenna along the back side of the pilot seat - attached to the center seat support structure.
ACK provides a mounting/retaining tray and straps for the transmitter/battery. To secure the tray/strap, Tee Nuts.
Per ACK-E04 installation manual, the ground plane for the ELT does not have to be a solid sheet of metal (as most builders assume). At minimum, it needs 4 wires/copper ribbons, with minimum length of 12" long, radiating outwards, from the center vertical whip antenna (provided).