ACR 406 plbs emit on both 121.5 and 406. No such thing as a "weak" enough signal to let you talk when that thing is going off. You will need to shut either off to talk on 121.5 or any frequency close to it.
I just found this out last weekend.

There is turbulence severe enough to set off an ELT - but I think mine is installed in a horrible place - the lid of my baggage compartment. The lid slamming shut after turb is probably what set it off.
Lee - you don't need to hack one of these gps interfaces up to the ELT if it has a NMEA interface. Dynon makes a standalone gps receiver for its skyviews - should plug right in, no? Or with a little wiring to whatever DB connector is required. It's probably nothing more than RS232 - which is 4 wires. Not TSO'd but it will work - and will work reliably. $200. The ELT won't care whether the signal comes from a TSO or not - only your A&P and the FAA will. And since you can velcro the thing to your skylight and plug it in/out for your annuals - I might be willing to take my chances.
http://dynonavionics.com/docs/SkyView_GPS_Module.htmlI know these same damn waas-capable cheap ass gps receivers can plug into your mode-s compliant transceiver - but because of the wording of the TSO requirements for ADS-B IN you are not legal to use them - you have to have a very expensive TSO gps unit that weighs a poop-ton for the moment to comply w/ ads-b in.