Going too cheap on a 'scope might be regretted. Buying too recent a low-end
instrument might be a disappointment as well. A 20-year-old 465 in really
decent functional condition and with al its parts and manuals can be had
nearly any day from a retailer of such hardware for $400, including a pair
of 100 MHz probes with most of their accessories, and often for less than
that. It (including the somewhat less well-suited 'B' version) will do
ANYTHING you need on most classic hardware. Knowing that, by itself, is
worth quite a bit, because you KNOW when you power it up, it will do what
you need. What might be even more interesting is the more or less
equivalent TEK 466, which is a storage scope. That will let you do even
more than the 465 and, when you can find one, won't cost much more.
A current-generation low-end analog 'scope will not begin to do what a
20-25-year-old one will do, because 25 years ago, the 20 MHz scope was the
typical workhorse. If you look at today's, it's a toy.
If you find a used TEK 935 (?) which was considered a "student" instrument
for use in schools, etc, it's all solid-state, which means you don't have to
use up $5 in power to warm it up, and spend $5 more for a six-pack to drink
while you wait, and, though it hasn't got the high bandwidth, it has the
delayed timebase, and two channels triggerable either externally or
internally, etc. You shouldn't have to pay even $200 for one of these,
complete with the two probes, which, by the way, are probably over half the
cost.
Dick
-----Original Message-----
From: Tony Duell <ard_at_p850ug1.demon.co.uk>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Tuesday, November 23, 1999 7:47 PM
Subject: Re: Oscilloscopes
>> I agree but I would not recommend someone dropping a couple hundred bucks
to
>> fix an old 20Mhz scope as I am sure they would not limit their use
>
>It probably wouldn't cost anything like that much... Most older 'scopes
>are easy and cheap to repair.
>
>> *exclusively* to vintage minis. A 20Mhz scope in RF/High speed logic
>> troubleshooting/design is totally useless. A 20Mhz scope isn't even very
>
>_Nonsense_. I've done a heck of a lot of troubleshooting on quite modern
>stuff using that 15MHz 'scope I mentioned earlier. It all depends on how
>you use your instrument and if you know how to interpret the results.
>
>> good at looking at the color burst of a video signal in any detail.
Again, I
>> find most folks design/troubleshoot in a variety of areas and that's why
we
>> need scopes with all the toys. I don't see Tek making any more 20Mhz
boxes.
>
>Maybe not Tektronix, but there are still 20 and 30 MHz 'scopes in the
>catalogues. And most of them are horrible -- they don't trigger properly,
>etc. You'd be _much_ better off spending the money to fix up an old
>Tektronix than buying one of those. Of course if you can afford a new Tek
>with all the bells and whistles, well that's great!.
>
>The other thing is that a Tektronix '20 MHz' scope will, in general
>display something useful for signals of a considerably higher frequency
>(I've 'pushed' a 50MHz 547 (_really old_) to at least 75 MHz). Yes, the
>amplitude calibration is off. All signals look like a sine wave. But you
>can still make measurements if you have to.
>
>At least one company seems to define an 'x MHz scope' as : If you turn
>the Y gain right up and apply the maximum allowed signal then you'll see
>_something_ at 'x MHz'. I am not joking...
>
>-tony
>
Received on Tue Nov 23 1999 - 21:23:57 GMT