Hmm...I have not destroyed any of mine yet, but that thin bit at the top has a slight lean on one of them. I do like your idea of the shrink tubing for support, so I made the fix by building them up (Left to Right). On the last one (black) I did not overlap at the top, as it would not shrink down to the size of the little whip of the antenna, but fits fine on the red. Even with the initial white tubing I could feel and see the difference with a slight shake. Each additional layer helped, as one would expect.
On the far right image of a different antenna, I made it progressive and longer. Each tube is 2 cm. It definitely re-enforces that spot.
I think I'm on my second SRH320A. The issue that I have with it is that the element above the "bump in the middle" is very flexible while the rest of the antenna is kinda stiff. That upper element will take a set if it's bent too far. As I recall, I accidentally broke my first one at that point. I keep wondering if a piece of heat shrink tubing about 2 inches long so it will bridge the upper element to the "bump in the middle" would provide some reinforcement to that junction.
I have all three versions of the 77CA antenna. No other dual band antenna I have tested beats them on UHF in the amateur band. On VHF it is definitely not as good as the 320A. I presume the repeaters you hit further were UHF. I can also see how the SRH320A performed better for APRS as it is much improved on VHF.
I have both the SRH320A and the SRH77CA and the latter is better. I can hit repeaters farther with better quieting. But oddly enough the 320 seems better for APRS.
