I recently purchased a RV-7 and spent this last week installing an ACK E-04 ELT. I was trying to figure out the best way to input a GPS source for the ELT. I did not want to break into the wiring harness for the GNS-480 at the moment, so opted for a separate GPS.
I originally looked at a Garmin 18x, but opted for a less expensive variant, the BR-355 GPS ($34 from amazon). I did not want to make a hack job of building in a 5V regulator and adapting connectors. Being that my background is in electronics, I went ahead and built a circuit board that had the same connectors. This is what I came up with.
The PCB mounts to the front of the ELT. The E-04 plugs into the 4 pin DIN connector. The BR-355 gps plugs into the 6 pin DIN connector. All it needs is 8-16V power into the 9 pin Sub-D. The Sub-D connector also has the serial lines from the GPS if you want to expert that to other avionics or ADSB receivers. A built in LED allows you to trouble shoot GPS connectivity without building the harness described in ACK?s manual.
With this someone could add GPS to their new or existing ACK E-04 pretty easy and cheap. Things get cheaper with higher quantity, so I was wondering anyone else would be interested in these PCB?s. I would just charge the cost of components. I estimate $15-30 depending how many people (not including GPS).