Interesting EBay item
http://cgi.ebay. com/Russian- USSR-Military- SPY-Direction- Radio-Receiver_ W0QQitemZ1303556 80856QQcmdZViewI temQQptZLH_ DefaultDomain_ 0?hash=item1e59c dd658
This was strapped to a soldier's body and he'd walk around with antenna looking for a transmitter.
More instructive is that the seller is hardly motivated but has drawn a line in the grassy dirt on price. Sad, is that many starving people have subsisted on just such a diet.