[Jayce]

I never really knew there was much difference between metal and glass tubes except for shielding and hearing at least some were internally grounded. Never seemed to matter much to the old service guys around here either it seems as I have had several radios with glass tubes in place of metal tubes over the years. Usually I haven't had much issue with a glass tube swap, but have had some radios that definitely played better with the correct metal tubes in place. Usually I will try to swap metal tubes back in when the radio calls for it, but my supplies have been dwindling and it has never been easy to run across metal tubes locally. Even the now defunct TV shop in town was running low on metal tubes before they closed. Glass or GT types have always seemed more common to find around here, which might explain why the radios I find often have glass swapped for metal. Add to the fact that scrappers abound or did abound around here, it is possible that any stores of metal tubes were just tossed in the hopper.

Edit: I should say that my supply of earlier 30's, 6 volt metal tubes has dwindled. Still fairly easy to find later tubes for AA5 sets.