3db
Coagie,
I just looked up 40kHz in the Radio Regs, it is allocated to fixed maritime mobile - they would not be putting a distress beacon in that band without guard channels. Also, a google search reveals a circuit diagram which has a loudspeaker symbol as the "final bit" and not an aerial symbol, so my apologies, you are correct. Must google before posting for things I am not familiar with!
3db, I messed up as well. I kept writing 43khz, when I should have written 37.5khz. I work off the top of my head too much without double checking. Anyway, thanks.