[Amps] Advice on instruments for ham use

[G3rzp at aol.com]

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