Thanks for the additional info, Gary.

As you can see, I'm having a difficult time understanding
just what the 7L12 does. There may be a typo in the data
sheet, but when I look at the time/div dial on the 7L12, it
just doesn't have the numbers to do anything slower than 10
ms/div. The other models in the 7L series have many more
sweep speeds available, based both on their data sheets and
on photos. I suspect that the 7L12 was different. In fact,
because the 7L13 has 100 Hz and 30 Hz RBWs, it would have to
have slower sweep rates.

Your finding with the 141 was that with a 300 Hz bandwidth
and 2 kHz/div width, a sweep rate of 50 ms/div was marginal.
I imagine then that a sweep rate of 10 ms/div (assuming that
would be compatible with the 300 Hz filter) would be ok with
P31. If I understand correctly.

I think we've gone about as far as we can without either
having a 7L12 in front of us or at least an op manual.
Thanks again.

73,

Chuck