[Radioroslyn]

Yes, as Terry said electrolytics will not hold up long in this application. 

Small value electrolytics are not rated for the ripple current they will be subjected to in a tube power supply filter. The lower the capacitance, the lower is their ripple current rating, and a modern 2 uF electrolytic was not designed to be an input filter in a vintage tube power supply. They will overheat and eventually fail.

Back when the 511 was designed, capacitors were expensive and so they used the smallest capacitance paper caps possible. These caps could however handle the ripple with no problem.

Today, the best option for replacement is a film type cap. They are designed to handle such service and will basically last forever. These are the type I use and have been very happy with their performance.

https://www.tubesandmore.com/products/C-FS-630

Thank you both for letting me know about this!  I never knew about such a thing.  I will be sure to get film type cap replacements.  So these are not electrolytic wet style caps?  Are these are modern dry caps?  I have several early AC sets, would you guys recommend these type of caps for all early AC filament sets with power supplies designed close to this model 511 such as Radiola, Zenith, ect?

Thanks

Jon

Hi Jon,
> So these are not electrolytic wet style caps?
Yes that is correct.

>Are these are modern dry caps?
Yes again. They are NOT electrolytic wet or dry.
They are non polarized film caps. Much like your
yellow mylar caps used the replace bypassing
 and coupling cap, only much larger in capacity.

Generally I would recommend using them in older
sets that have small capacity filters.

Terry