[Milsurplus] RAX receivers

[Mike Hanz]

On 10/29/2010 2:45 PM, Mike Morrow wrote:
> I like the very interesting photos that you have of the radio installation
> for a PB4Y-2 at http://aafradio.org/sidebar/PB4Y2_Line_Maintenance_Manual.html
>
> It appears that the antenna lead for the RAX-1 units is NOT directed to
> the receiver antenna post of the ATC transmitter above the RAX-1.  There seem
> to be routing brackets for the RAX-1 antenna lead AWAY from the ATC, but it
> also appears that the lead is short as if in fact it was to be connected to
> the ATC.  It looks like the end of the RAX-1 antenna lead is already stripped
> of insulation for that purpose.  Maybe my interpretation is wrong...I suspect
> that the RAX-1 antenna lead would have been fastened to the ATC...but I don't
> understand why that lead appears to be in brackets heading downward, not
> upward to the ATC.

Good eye!  I went back and looked at my original high def scans, but I 
didn't notice any more Adel clamps for the RAX antenna lead below the 
stringer between the ATC and RAX sets, though.  It could have gone to 
the ATC, but it also looks like it /might/ have reached the back of the 
lowest terminal in the antenna patch panel above the ATC as well.  There 
are two of those patch panels with the spark plug tips on them...1/2" 
Plexiglas, they look like.  That capability would allow some swapping of 
HF antennas for various reasons, both transmit and receive, command and 
liaison.

> There's also a C-26/ARC-5 to the left of the ATC that appears to be
> for the R-26/ARC-5 that's in the rack with the R-23/ARC-5.  The R-23,
> R-26, and ARB/ATB clearly share the same antenna.  It wouldn't
> surprise me if there wasn't an intent to use the R-26 as a backup
> liason receiver.

That makes sense to me, too.

> The ARB and ATB appear dedicated as HF command sets with controls for them
> only at the pilots' position.  I'm surprised that there's not a radio
> operator's control box and tuning dial for the ARB at the radio operator's
> position.  It appears that the ARB was NOT an option as the ATC's liason
> receiver in this installation unless the pilots were going to control it.

That's a good point, although the crewman sitting at the ATC position 
might have had a primary job of surveillance rather than radio 
operator.  After all, the pilot/copilot very likely already had the ATC 
controlled with the Navy version of the C-87 and therefore needed 
something to do, what with the VHF set being the ultimate *primary* 
comms capability in 1944... <ducking and running>:-)

While a compelling presentation, the close association of the ARB 
control head and ATB control may or may not be significant - we just 
don't know, since I have no photos of the left and right sides of the 
flight deck.  I find it unusual for the ATC and whatever served as the 
liaison receiver not to have a remote capability for the flight command 
crew.

- Mike