The 406 is quasi spread spectrum, and only on for short bursts. dont waste your time with it. The 121.5 , which is supposed to be phased out (sadly, big mistake) is AM and most of the ham radio double ducky type antenna switching direction finders will therefore not be able to home on it. Get a old aircraft radio, have a local ham disable the transmit. Tune it to121.5. pull out the "agc" ie automatic gain control signal, isolate it and tie it to a meter. Buy a yagi antenna for that band with at least 4 elements. Put the yagi on a stick to get it away from your body. Buy a couple of inline antennuators from digikey ie
30db, 20 db, 10 db, and 3 db. As you get closer, stick in the next biggest attenuator in the cable to knock the signal down. Hunt on 243 for non military epirbs, the harmonic will always be very weak. For very close in, hunt at 364.5 , this will be a very weak signal resulting from harmonic generation in teh output stage. You'll need a yagi with gain for that frequency.
If your really in trouble, tie a rope to your handhand 121 receiver and lower down a short piece of metal pipe, just a bit longer (say 4") then the radio plus antenna length this is the "waveguide beyond cutoff" technique and attenuates the signal nicely when your close in. IE the pipe shields the antenna, on a hadheld, the whole radio, body AND rubber ducky, is the antenna
I still have a hard time beliveing a USCG search team would not have a compentent Radio Officer around, and no access to regional or national consultant or local hams. If your really USCG, try talking to your local CAP squadron, they may bebetter able to teach you.
Steve Roberts