On 14/03/2010 17:44, MartinR wrote:

So a miniature radio, altimeter and temperature gauge are worthless?

The ones I used to help launch at Crawley used thermionic valves!

MartinR

The one we found in Kingsdown wood on the East Kent coast in the late
seventies used thermionic valves, and a little one-use-only lead acid
battery or two to provide LT and HT. It had a note on it which I think
said that tampering with the battery was a really bad idea, it was an
obsolete design, and would be please dispose of it. It had been launched
from near Gravesend.

Needless to say, once the battery was rendered non corrosive, disposing
of the thing wasn't exactly at the forefront of our minds.

Several years later, the one we found in the Thames was transistorised,
but drowned ...