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At issue is that the stretching occurs even when the trace is not extended
past the top or bottom graticule. It isn't horrible but quite noticeable. I
have another 7704A, two 7603s, and a 7514 and none of those show this problem
quite like I see it on this 7704A. Yes, with an AC signal that approaches or
passes the CRT's vertical limits, I see rippling on virtually all these scopes
and I understand that but this "stretchy, multiply-scanned image" thing is
only seen this way on this 7704A.

Again, it isn't like I can't read the characters, etc., it just seems it is
abnormal and would like to find out why.

Thanks,
Barry - N4BUQ

I looked back through this thread, and I don't know what the deal is here,

so

please forgive if I've missed something. In the OP, I think it was an issue
about the readout distorting severely when the vertical signal is

over-driven

and off-screen. This is entirely normal behavior. The Tek verticals tend to
have great dynamic range, but even they have their limits. I think that

Albert

et al have touched on this in previous messages about what it looks like at
normal levels.

If the RO works fine with signal displays on-screen, or a little beyond,

then

fine. If they don't do as well way off-screen, then you're tilting at
windmills. The RO is irrelevant if you can't see a waveform anyway. If you

see

weird non-linearities or stepped conditions on overdrive, it's likely

thermal

delays, sweep rate, and RO framing rate getting into the picture too. What
matters is how it looks when things are "normally" displayed. If OK, then

case

closed. At certain sweep rates and vertical excursion, it's quite normal to

see

the RO rippling up and down a little. The question is, what's acceptable. It
should be not obnoxious, and preferably, but not invisible.

Ed