Nice on the 1590A, I am actually looking at one now. Far as I can tell the difference is very slight between the two. The sweep generator is dead on this unit. I was testing the single shot but it doesn't trigger correctly as it will not reset. If it's on auto, not normal but only auto, you can watch the triggered light come on as normal. If my assumption is correct I can grab this 1590A and swap out the sweep. On a related note, I do have a 100% working Tek 2245A on the way. But this BK has won my heart so I'm still going to fix it.