[Eliot Ness]

If the Hickok Simplex model 36 tube tester is this one:

https://www.ebay.com/itm/Hickok-Simplex-...7675.l2557

Then I'd have to agree with Mike that it probably wasn't a very good choice.

My personal favorite tube tester is the last one on Mike's list, a Precision model 10-12.  My main likes are its ease of use and accuracy against tested known good and NOS tubes.  I recently went through a smaller Precision model 920 that belonged to a friend and it works very nicely also.

The problem with buying a tester from eBay is if you don't know the seller, and they don't know how to properly check to see if a tester works properly, you run the risk of getting a unit with a bad meter or other defects that might be hard to track down if you're new to all of this.

My preference for buying a tester is from a trusted friend, a hamfest or radio meet where you can plug it in to make sure at least the meter works.  I have a friend with an abundance of tube testers and he is slowly selling them off.  I'm not sure what your price range is but if you bought one from Terry he would guarantee that it works and he is quite honest.  What he has left might be out of your price range, but if interested shoot me a PM and I'll send you his email address.  Be ready to tell him your price range and what style tubes you want to be able to check.  Good luck!