I know, I'm lazy. Is a locator beacon which operates on 121.5 still acceptable ? I have a feeling that there is a new frequency these days ?
Every beacon transmits on 121.50MHz. That is what the rescue vehicles use for VDF (VHF direction finding) to find you when they are within a few miles. This is not changing.
What has changed is the need for the other frequencies on which the beacon transmits as well.
243MHz was widely used on fixed beacons (ELTs) but the satellite monitoring of that frequency is AFAIK gone, as of about 2009.
406MHz is now the only frequency which is satellite-monitored and most (all?) mandatory-beacon-carriage regs require this.
The other factor is whether the beacon has a GPS. If it does, the GPS data is transmitted with the 406MHz signal and the satellite network passes that on, so they can find you potentially a lot quicker.
Thanks Pete, I saw an old Tron for sale and wondered if it was worth bothering. Clearly not :-)
It will be slightly more useful (longer range) than the famous Breitling watch with the built-in 121.5 transmitter 
