I would be a bit leary of a digital scope. the reason for that is that if
you put ina well modulated RF signal, the possibilities of aliasing are
frightening. I demo'd this to a HP rep - a 500 Megasamples/sec scope with a
30MHz
signal modulated 80% at 1kHz. He agreed that it was 'difficult' to decide what
was the truth!
The Tek 2000 or the earlier 470 series are pretty good. I'd recommend a
100MHz bandwidth job: even brand new probes aren't that expensive, so it's
worth
getting them. I have both Hameg and Gold Star scopes: they're fine, but a well
restored second hand Tek is likely to be a winner. I'd also advise getting
the full handbook/service manual. Newer scopes may well have special ICs in
there that are impossible to get. Also, try to avoid scopes with tunnel diodes
in the trigger circuits. This is because tunnel diodes are not only very hard
to find, but deteriorate over time, even when not used.
Remember, too, that scopes are nearly as bad as spectrum analysers - both,
given a chance, will lie like a personnel manager! Some 20 years ago, the Tek
rep was trying to sell us a new scope. The accuracy of the amplifer was 3%,
but he claimed that the digital calibration to 3 significant figures was
meaningful....
73
Peter G3RZP
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