Nice clean BC-224, you get extra points for the loudspeaker! I always wanted one but not willing to shell out the$50 to a $100 they are going for these days. Just like the BC-348 apparently, if you want to be the "Big Time" collector, you got to have one. Imagin in your case you picked them up at some point in the past where they were cheap, but those days are gone! I saw one at Gilbert for $50 and several at Hamvention that were $60 and above.

Enjoyed the writeup about the dropsonde, amazing what they were able to do without microprocessors and the like, on the subject of modern students I have seen them use Microcontrollers to simulate basic logic gates.  Too much trouble to use a 74 series or 40 family devices, lets model operation of a AND or OR gate with an Arduino. Or better yet use an Arduino to latch a led on or off.

Ray F/KA3EKH