ACK E-04 ELT

[Rick524]

I'm trying to connect my Garmin296 to my ACK-04 ELT so the elt receives lon/lat updates about once a second.
It appears the gps is sending data to the elt, but the elt isnt responding. I've tried 9600 baud and 4800 baud
nema outputs from the gps with no luck.
Has anyone had success with this setup?

Thanks!
Rick
Sonex 524

[Jason]

Rick,
I'm the manager of the experimental division of Aerotronics, we build custom "Plug and Play" panels for experimental aircraft. I've been using the E-04 almost exclusively since they began production. Its a great ELT and the GPS position function is a wonderful addition. Here are a few pointers to consider.
1) you'll have to program the GPSMAP 296 to output the GPS position, in the setup menu you'll be looking for the "COM 1" subtitle. under the "Serial Data Format" select "NEMA in/NEMA out". This should be a 9600 baud rate.
2) I assume you have the Power/Data cable, you have to use the blue wire from this harness and run it to the ELT.
3)The ELT will also require power and ground to operate the GPS function. That little four pin connector at the ELT is a bit tricky and difficult to solder without bridging two pins. I would use a multimeter to confirm you have power and ground in the correct pins. You can also measure for VDC (volts DC)on the wire coming from the GPSMAP. An analog meter is easier to see however a good digital will pick it up as well, the NEMA output from the 296 can be measure and you'll be looking for a 5 VDC pulse typically once a second however if I remember correctly the 296 updates once every two seconds. You have to make sure your outside and the GPS is locked on. The manual for the ELT shows how to wire in a LED thru a resistor to one of the pins at the connector. Basically the ELT will receive the GPS signal and if its valid retransmit it out to the LED. This will result in the LED flashing with the GPS update rate. The ELT can be configured for various baud rates however it comes defaulted at 9600 baud. So you shouldn't have to mess with it.

I have many customers struggle with the small connector at the ELT, for this reason I ordered and stock extra connectors and will often solder them up with a length of wire, the LED already installed and mail them out. I'd be willing to do this for you as well if your having a tough time with it. I hope this helps

Jason Smith
Scratch building Sonex #460
Aerotronics 406-259-5006

[Rick524]

Hi Jason, thanks for taking the time to reply to my message. I'll answer you here rather than on Sonextalk as this
isnt totally Sonex related.
I worked as an electronics tech for 38 years, but mostly on communications equipment. I have no problem soldering
cables to connectors. I've checked the plug to the elt and its good. The data from the gps is there on the blue wire
(com 1). I set up comm 1 on the gps for nmea/vhf out, which is 9600 baud (no choice). Also installed a jumper in the elt to make it 4800 baud and set the gps com 1 to nmea in/nmea out, which is 4800 baud. As before, I can see the data going into the elt with my dvm or with the led tester, but still dont get any change in state on the elt transmit line (pin 2).
It seems like the elt isnt happy with the data its receiving and wont acknowledge it. I think my next step is to connect my laptop to the gps and run a communications program like hyperterminal and see whats coming out of
the gps. The elt manual shows what format it expects to see.

Thanks again for the help Jason. I'll post a message here when I figure it out.

Rick
Sonex 524

[Rick524]

It works! In the ELT manual, page 18 note 1.......under advanced nmea settings in the 296, set the speed from fast to normal and the Garmin priority to off. :mrgreen:
Tried both 9600 and 4800 baud settings and no problems. Now, back to airplanes.

Rick
Sonex 524