[Amps] 3CX1200Z7 backup tube?

[Eric Irvine]

I just acquired an Ameritron AL-1200 for HF contesting, and am considering
acquiring a backup 3CX1200Z7 tube. I understand that tubes can degrade if
unused for several years -- should that be a concern with this tube?  It'll
be a pain to swap out tubes every few months to keep the backup tube in
shape. With the quality of this tube I'm expecting it won't need replacing
for quite some time but its my inclination to get a backup.

Eric
VY1EI