Re: gEDA-user: Need opinion on O-scope

[Dave McGuire <mcguire@xxxxxxxxxxxxx>]

On Aug 24, 2008, at 8:09 PM, Dan McMahill wrote:
>>> I found an oscilloscope on ebay that the asuction ends tonight.   
>>> At the risk
>>> of gettting someone else interested in it it's at this link:
>>>
>>> http://cgi.ebay.com/Tektronix-7854-400-Mhz-Digital-Analog- 
>>> Oscilloscope_W0QQitemZ170253977697QQcmdZViewItem? 
>>> hash=item170253977697&_trkparms=72%3A552%7C39%3A1%7C66%3A2%7C65% 
>>> 3A12%7C240%3A1318&_trksid=p3286.c0.m14
>>>
>>> It's been years so I'm asking everyones input on this scope.
>>
>> I have the Tek 7903, so some things related to it will apply to the
>> 7854. These are 20+ year old oscilloscopes. Expect to have to
>> occasionally do a repair. Mine has needed it 3 times. Two were failed
>> (shorted) tantalum caps and the other was a connector that was
>> corroded. There are some Tektronix proprietary parts in these scopes
>> that you will only be able to get from a parts scope. Other than all
>> that the Tektronix 7000 series are very nice oscilloscopes. Whenever
>> mine dies and can't be fixed, I am not quite sure if I will get
>> another or go for a digital scope.
>
> I'll second what Darrell said.  I don't have that exact one, but  
> the 7k
> scopes were quality units.  There are a lot of plugins on the market
> which can offer you some nice features.  For example the 7A22 plugins
> will get you down to 10 uV (yes, that 'u' as in 'micro') per division
> which can be pretty nice for some things.
>
> Really I only have 2 complaints about mine.
>
> 1)  I only have about a 100 MHz one and I wish it were faster.
>
> 2)  It is heavy and my tolerance for heavy things has gone down
> significantly over the years.

   I've owned a 7704 and a 7904, and currently have an R7603 (hosting  
a 7CT1 curve tracer) and have found them all to be great units.  The  
7000 series dates back to the early 1970s, and the fact that there  
are so many of them still out there working everyday in labs says a  
lot about their quality and utility.

   They are maintainable and readily available.  There are plug-ins  
to suit pretty much every oscilloscope application, and even plug-ins  
to turn it into a curve tracer or a spectrum analyzer.  Documentation  
(both user and service manuals) are readily available, and user  
support is excellent...there are even quite a few mailing lists and  
forums that are frequented even by some of the guys who DESIGNED  
those scopes.  (Yahoo's TekScopes list comes to mind)  You can't get  
support that good with current-model equipment.  Really worried about  
it breaking and not being easily fixable?  Buy two, they're cheap.  A  
loaded one goes for ~$200...a thin one goes for half that, even less  
if you don't have to pay for shipping.  These are scopes that cost  
more than cars in 1971.

> I drool when I see these lunchbox sized scopes that weigh about 5 lbs!

   Yeah, but the nice small ones are always digital  
oscilloscopes...completely different instrument, as you know.  I've  
got a Tektronix TDS3012 lunchbox-sized digital scope that I love, but  
when things get dicey on the bench, out comes the Tek 2465A analog  
scope.

              -Dave

-- 
Dave McGuire
Port Charlotte, FL



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