Hello everyone

 I want to get the longest life out of the 5 foot Y12 GB made  tube that been imported from united kindom the question is
Wich ballast is the best to use for tube life? I have 5 foot preheat/ switch start ballast and HO SRS  ballast.

Jeremy

I think Switch Start and electronic starter with preheating time

It depend on how the tube will be used:
For occasionally used showcase I would use preheat circuit with manual preheat start: It is simple and there is nothing to degrade and so change parameters over time.

For long time use per start the SRS would mean least stress on the filament wire (the current to the arc is fed from both sides). But this ballast start the lamp with not really completely heated up filaments.

A HF ballast mean less stress during the running phase (quite constant ionization, no electrode cool downs and reignitions after each zero crossing,...), but they will cold start the lamp, so usable only when there will be only very few starts.
Programmed start ballasts won't help, as you will likely not found any designed for correct operation with such old lamp (without premature cold-ignitions)
IS ballast with one wire per lamp end does wear the electrode more during each start, but will be able to operate the lamp even when the filament break (the older T12 tend to suffer from structurally brittle filaments)

For frequently switched place the preheat with an electronic starter (S10e,...) would be the best - no cold starts,...

Thank Medved

 It look like I will Go with a manual preheat option by drilling out the starter can place a normal open switch
In it,. That way I am not modding my fizzy light pack.

The SRS is raising a question to me in 1 aspect. 5ft 58w T8 is 670mA and i expect that this is the correct current for 65w T12 too. HO lamp is about 800mA. The 65w T12 is meant to accept either 670 or 800mA, but i guess that at 670mA it is warm enough for proper hot cathode discharge, then the 800mA will only wear it faster...

The HO is not 65, but 80W.
There could be tubes rated for both, but they would be labeled correspondingly (like 65/80W or so).

I doubt a tube labeled only "65W" would be rated for the 800mA ballast.

To carry the extra load, the HO tubes have special electrode arrangement (extra anodes) to relieve the filament, without such feature the higher current will most likely overheat the filament...