Lest we not forget the Radio Logging Whistle. 

Proper name I now know as 
"Electro-Bug" Radio Whistle
  These units were used by the Highline logging outfits to signal the Yarding Tower,
 when to pull the logs in after the choker-man hooks them up. 
They were a transmitting belt, worn by the chokerman, with a base receiver unit in the tower.  

I had a sketch of this unit online until
I received an email Feb 10, 2013, from Ron Kondrat.
Turns out Ron was a Factory Technician
At Challenger Electronics/Baron Communications
 from 1979 to 1987.
He used my drawing, and added the technical notes.
Thanks to Ron for the info.
Turns out they had competition in the field.
Ron worked on these as well, and brought back some memories for his as well.

It was the main competition to the Rothenbuhler Engineering "Talkie-Tooter".

      The belt "transmitter" unit was made from stainless steel, in a semi-circle design riveted to a leather belt.  In the belt a flexible 10-12” antenna was inserted. Inside the transmitter unit was 2 circuit boards, and a nicad battery pack.  Each set had it's own frequency, so no chance of cross signals in the field, from one operator, to another.   They were finicky to work on, and always seemed to be in for repair.  The choker-man took out his frustration and possibly requiring a work break, by beating these units to death.  I swear some were driven over by D8 Cats!   The receiver's barely ever needed repair, as they were bolted to the wall in the yarder, so took very little abuse.  The odd bent antenna, or broken power wire was about it for them.
       We had customers like Skoglund Logging, Brown Brothers. Crown Z, and various others.  They were expensive to rent, but also expensive to keep running. 
        Before the Radio Whistle, this job was done by "Whistle Punks", who would stand on the side of the logging show, and when they seen the Choker-man finish putting the choker on the selected log, would pull a rope and signal the operator of the yarder, to pull the main line in.
       These units were obviously a better system than that.
       Most of the other guys on the crew hated working on them, but I think Ken Rowe and myself enjoyed every minute of it.  They were a real challenge.  Especially with a burly logger with cork boots, standing waiting at the door, to pick one up, for the next days early shift.  You learned to be a diplomat, as well as a radio repairman.  I can honestly say, they were all great customers we dealt with.  They also understood how these things could be mangled, and would be repaired in minutes for them.
      They couldn't operate without them, and we knew that.
      For some strange reason, BC Tel quit renting them, and like other profitable parts of the business, were sold off.  Between mobile radio installs, these were our filler job.  Some bean counter didn't see it that way I guess.