Ronny Svendsen asked some interesting questions about the use of red on the Skyhawk crush points and the A4D-2N (A-4C) radome change that caused me to go back and review those details. The crush-point question resulted in the post just before this one. I've just added some additional pictures to it and a comment by Rick Morgan with respect to the purpose of all that red. I also went looking for more radome examples. I had originally mentioned the change from the A4D-2N nose with the large black radome to one that was mostly gray/white with a small area of white or black on the tip. See http://tailspintopics.blogspot.com/2010/07/a4d-skyhawk.html.
It appears that this change may have been made with some urgency, because I've now seen several examples, some furnished by Ronny, of the later radomes that are probably field replacements because they are a solid gray that doesn't match the color of the forward fuselage and the black anti-glare paint does not extend forward onto the radome as it subsequently would. This is an example:
The new radomes also appear to come from different sources (two are tipped in white and two in black) which suggests an effort to field replacements as quickly as possible by buying them from more than one manufacturer.
I'd still like to know why the change was made and how the new radome differed in construction from the original one. For example, was the transmissivity now limited to the small area on the tip of the nose or was that just an erosion-resistant coating?