I just ordered some 6BQ7As, 6N1P-EVs, and RCA 5U4G ST from eBay. Although these tubes are claimed to be "tested good" by fine rated sellers, I am still somewhat concerned about whether it is safe to try tubes on the Stratus without testing them by myself using a tube tester. However, I don't current own a tube tester.
What do you guys think? Do you own a tube tester? And, is there any (rule of thumb) eyeball test that can be done? I am also wondering if the Stratus has some built in protection mechanism against malfunctioned (such as shorts in tubes) or incompatible tubes.
In addition, as a more specific question, is the RCA 5U4G ST compatible with the Stratus? Specification wise, are they identical to a regular 5U4G?
To my knowledge, ST merely refers to the coke bottle shape of the tube. If it's a 5U4G then it's completely drop-in.
My rule of thumb on the fleabay is to only order tubes from a place I know or that have been tested and THE RESULTS POSTED. You never know what you're going to get when it says "tested good" or even "tested 100%." If they know what they are doing then they will post the results for each triode or section so you know that you are getting internally matching tubes as well - very important. If they don't post that, then I figure they're amateurs or they're hiding something and preying on amateurs.
In terms of safety, unless you have a tester I think there's little you can do to be 100% sure. In the case of a driver or output tube, things wouldn't be so bad - the amp just wouldn't work. The rectifier is the one you need to watch out for. I blew two rip-off rectifiers in my BA and nearly blitzed one of my ears...