[ARC5] More on the BC-1206

[Robert Eleazer]

Continuing with fiddlin' with my BC-1206's I now I have two that work.  The BC-1206-A, the one with the 28D7, worked after some tube wiggling.  Further examination revealed a design flaw.  

 

The tube sockets are held in place by pan head machine screws.  This is no problem with the octal tubes (ever notice the raised portion between the plug and the skirt on metal tubes?  It provides good clearance for the screw heads).  But for the 28D7, a Loctal tube, the combination of the lack of space between the skirt and the plug and the itty bitty short tube pins, leads to the tube not quite fitting in the socket tight enough to make good contact.  I am going to replace those screws with special low profile pop rivets.

 

As for the question of why they used two tubes in some cases and used the ones they chose - the only installations I know of for the BC-1206 were in fighter type aircraft.  The set did not work through an audio source switch but was wired into the same circuit as the SCR-522.  It was possible to hear the 522 and 1206 simultaneously.  Pilots even had to be cautioned to not try to talk to someone using the 1206.

 

These were mostly single seat fighter aircraft, so there was only one set of headphones to drive.  I don't know if the 1206 got any audio assist from the 522 audio.  The only multi-seat aircraft that I have found used the 1206 is the P-61, and in that case the radio was mounted in what must have been a highly awkward position behind the pilot's right shoulder, facing forward.  Even in the P-61 there was no reason for the radar operator or the gunner to hear the BC-1206, so I doubt they could.

 

The BC-1206 was very obviously suitable for the type of use in light aircraft that Dave is so enamored of (Dave: will send you pictures of my Lear set).  But I do not know if it was ever used for that purpose. 


Wayne