[retailer]

The 45B is a nice valve tester and is quick and easy to use with the ease of use coming from having only 3, 9 position selector switches marked A B and C to set up the valve element connections for testing. This compares to other testers that use anywhere from 9 to 13 switches. There is a few down sides to this though - as new valves came on the market the engineers at Taylor found that some valves could not be accommodated, one the most notable and common types is the EL84(6BQ5).
This led to the introduction of the 45C which increased the number of switch positions to 18. The other down side is that if a valve is not listed in the data manual then it is up to the operator to work out the A B C switch positions for that valve - this can take a bit of time to get your head around. To complicate matters further there seems to be at lease 3 versions of the valve base wiring so you need the correct manual for your tester.
Some years back one of the members of this forum ( I forget who) I believe wrote a program (I think in Javascript ) to do the heavy lifting so to speak, once the valve pinouts were input it would work out the A B C switch settings, I also believe a link was posted for use by forum members. At the time I had also written a program in VB to do the same thing I didn't bother posting a link as the Javascript version was available but I do recall sending a copy to the forum member that had written the Javascript version.
If you can get the Taylor for a reasonable price and it is in good order then do so, it is better than an emission tester and also better than the crop of testers such as the Eico 666 that are part way between emission and GM testers. While it is not as comprehensive as say an Avo it is a lot easier and quicker to use.

You can get around the EL84 issue by making up a B9a Novel to octal adapter taking care to wire the valve elements as a 6V6, this allows you to use 6V6 A B C settings.