At Dr. Fretgood we currently do not have a tube tester.  Why?  Well I'll do my best to keep it short.

Tube testers are good for testing the following aspects of tubes: shorted filaments, shorted internal plates/grids etc, some testers test the mu or gain of the tube.  Does a tube tester tell you if a tube is definitely good and will work in your amplifier?  NO.  Does a tube tester test for microphonics?  NO.  Most tube testers do not test tubes at the high voltages that are inside a guitar amplifier.  The short of it is this.  THE BEST WAY TO TEST A TUBE is to put it in your amplifier.  You can then be the judge of the tube's tonal characteristics, and microphonics.  If said tube has a short typically the worst that can happen is that the fuse blows.  Fuses are $1.00.  Finally, if you feel more comfortable having us at Dr. Fretgood install your tubes then we're happy to do that for you.  It's best to have us perform this service if you're installing new power tubes in a fixed bias amp as power tubes more often than not need to be biased.