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100 Tek 535 oscilloscope with some plugins




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This article is from the Antique Radios And Phonographs FAQ, by Hank van Cleef vancleef@netcom with numerous contributions by others.

100 Tek 535 oscilloscope with some plugins

I have a chance to get a Tek 535 oscilloscope with some plugins for
a very reasonable price. Is this a good thing to have, particularly
when you say that oscilloscopes were rare in service shops in the 30's
and 40's?

Grab the scope, if it is working and calibrated, and has had the
selenium rectifiers replaced with silicon (Tek made conversion kits for
this).

There's been some thought given to coming up with a Tek Scope Faq. Stan
Griffiths published a very good little book (available from Antique
Electronic Supply) on old Tek scopes named "Oscilloscopes: Selecting and
Restoring a Classic." Both Stan and I worked for Tek, and we've been
holding something of a steady forum on the boatanchors list on the
topic. In the used market, Tek scopes abound, for quite low prices,
considering what they are. The most common models are the 545A, 535A,
and 547. Almost any of the others in the 530-540 line are good scopes
that come back to life quite well and give yeoman service. The common
plug-ins for these are the CA, K, and G, and you will want at least one,
if not all three. The 547 requires a 1A1 for full bandpass, but will
work with any of the letter series. These scopes are big and heavy,
around 65 lbs, and gobble up about 500 watts of power.

On smaller scopes, the 561A with plug-ins is a good scope, although
limited to 10 Mhz bandpass. The 310 is a little (3" tube) cutie that
can be very handy, although they are somewhat prone to overheating if
you try to run them all day. I'm not going to try to sum up what is in
Stan's book here. He has 200 pages devoted to descriptions of old
scopes and plug-ins, and the vast majority of the equipment described is
good for working with radios. The later 7600 series scopes with the
right plug-ins are also good choices, but tend to be more expensive, and
more difficult to repair.

I'd pick any of these over the 585 (which does NOT work with
letter-series plug-ins unless you have a special adapter), some of the
specialty scopes like the 517, 519, and 502.

On other brands of scopes, Hewlett-Packard tried to compete with
Tektronix for a while. Some of their scopes, particularly the lower
performance units, were fairly good, and some others were marginal. The
Fairchild-Dumont 766H was at least the equal of the Tek 547. However,
so far as I know, they are more or less orphans today, with very few
people having documentation, spares, parts units, etc.

Other scopes? Most of the others are much lower performance scopes than
the Tek 530-540, and a good many of them are lower quality as well.
Unless you are a scope collector, don't bother with the WWII-era P4
synchroscopes, the old RCA's, or the pre-Fairchild Dumonts. One
particular group of scopes to avoid is the Lavoie, Hickock, and
Jetronics "Tek wannabe" scopes that government agencies bought in large
quantities. These, along with "Tek wannabe" plug-ins, are easy to spot.
They look like Tek stuff, but don't have any manufacturer's name on
them. Identification is by a screwed-on nameplate. Genuine Tektronix
has the Tek logo, the name "Tektronix," and other very clear markings on
it. These are, to be blunt, nothing but electronic junk.

My personal preference is for simpler scopes. I use a 533A or a 310 for
most work, and don't find myself at all hampered by 15 Mhz bandpass
(533A) or lack of a delaying sweep (useful for pulse and digital work),
or a dual-trace setup. The real value provided by an oscilloscope is in
qualitative graphic displays. For serious quantitative measurements,
other test equipment is simpler and more accurate, and it takes a good
deal of skill and experience to set up and use an oscilloscope to make
good quantitative measurements.

While you can buy "repairable" Tek scopes and plug-ins regularly for
$10-$50, I feel reluctant to advice the novice to run right out and to
this. Stan Griffiths has about as much experience working with Tek
scopes as anyone, and I certainly would not want to get into a
productivity contest with him. Both of us feel that trouble-shooting a
sick scope is fairly straightforward and easy, and we buy "repairables"
and fix them fairly quickly and easily---most of the time. But a 545
has something like 75 vacuum tubes (I never counted all of them---there
are eight here, ten there, seven more another place, etc.), and someone
who is not familiar with Tek scopes and trouble-shooting methodologies
in general might have a terrible time. Both of us have bought stuff
and found, when we started trouble-shooting, that someone had been there
before us and "fixed" almost everything except the real problems. It's
obvious that somebody else tried to fix some of these, and couldn't.
Both of us have specialized test equipment, and both of us know how to
set up a completely uncalibrated scope. For someone who isn't really
prepared to play "scope wizard," and who wants a solid, reliable scope,
finding someone who knows Tek scopes and who has
clean-working-calibrated units for sale for $125-$150 may be a lot
better bet.

 

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