is the led on a 1st series phantom tx  red

Yes - it's red.
The TX is an SL6 model, I believe.
Here is a description of how to bind a new one to your quad.
http://droneflyers.com/talk/thre ... r-to-phantom-1.723/

Note - the FC40 model would be different - 5.8GHZ

Well... that depends.  I have two different DJ6 2.4 GHz remote controls.  One has a red indicator and the other has a green indicator and 3 beeps when turned on.  See the screen capture for the firmware versions. (I am not doing the v1.0.2.26 firmware because I do not have an A2 flight controller)

droneflyers.com Posted at 2014-12-29 06:54
Yes - it's red.
The TX is an SL6 model, I believe.
Here is a description of how to bind a new one to ...

Holy cow!  I just watched that video and can't believe how it AND the DJI Phantom 1 documentation is so out-of-date! You had to actually open up the Phantom just to relink the transmitter?!?  The same "Advanced Manual" (dated 2013-03-22) also shows you had to open the remote control and physically rewire it to change between mode 1 and mode 2!! (you can now do it with just a mouse click in the DJI NAZA Assistant).

Back in August 2013 DJI came out with an upgrade kit kit to the main board with integrated PMU(Power manage unit) and GCU(Gimbal control unit)，and has added ports for wireless video transmission module and Zenmuse H3-2D.  I don't know when they actually started including the new board in the production models but my first Phantom 1 v1.1.1 I bought from Woot.com in Feb 2014 had that as well as some additional featured they neglected to include in any of their documentation on the support or wiki websites, namely you DON'T have to disassemble the Phantom simply to relink the Phantom and remote control!  All that is required now is to stick your finger in the battery box and push the button!
By the way, the manual for the FC40 does have updated instructions!

My P1 was purchased November 2013, so it didn't have that button....unfortunately!