textronix 3a72 scope
 

Just picked up ( actually it too heavy to just pick up)
one of these old boat anchors. The cost was less tnan
a large coffee so I guess the fellow Ham wanted to move
it out of his basement!!
It makes a nice squiggly line when plugged in but without
a manual, I may have to turn it into a back doorstep.

No hits back on a "google' on this model.
Anyone familiar with this unit??

George- Nova Scotia

Hi George,

The 3A72 is a plug-in amplifier not a complete scope. You
probably have something like a Tek 561, 4 or 5.

Have a look here for more info.

http://www.barrytech.com/tektronix/v...ekvintage.html


Cheers - Joe

Hi Joe,
Of course, you,re right - I only read the marking
on the amp. It,s a Tek 568 and looks like
a pretty nice unit. Must search for some
more info on it
Thanks

George

On 8 Jan 2005 12:37:22 -0800 (George)
wrote:

Just picked up ( actually it too heavy to just pick up)
one of these old boat anchors. The cost was less tnan
a large coffee so I guess the fellow Ham wanted to move
it out of his basement!!
It makes a nice squiggly line when plugged in but without
a manual, I may have to turn it into a back doorstep.

It's one of the very early 3 series Tek vertical amp plugins for the
560 series of scopes. You mentioned that your scope is a 568, but
which time base plugin does it have?

I like the 560 scopes, but the max bandwidth is only 10 MHz. For the
3A72, the bandwidth is only 650 kHz. The 3A1 and 3A6 will give you the
full 10 MHz bandwidth, and there are lots of specialty plugins which
are available out there for fairly cheap.

The 568 was made to work with a special digital unit which I believe
was supposed to readout times and voltages in digital form. I'm not
actually sure of what it was supposed to do, but it's mentioned in
Stan Griffith's Tek book. I've never worked with one.

Personally, I am most fond of the 564B, which is a later solid state
storage scope mainframe, but still limited to 10 MHz.

I'm always amazed at how often 10 MHz is plenty.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
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Jim- The time base is a 3b2 and the amp is a 3a72.
Just downloaded the complete manual from BAMA=
all 100+ pages.!!! Its going to take a while to see
if I figure out this "tool". I understood it could also
be used as a signal generator but the manual reads as if I should
already know all these things?
One of those BNC connectors must be used to input a signal to the
scope and/or output a
455khz sig. I,ve got the whole winter to play
with it.
George VE1NK

On 11 Jan 2005 15:53:32 -0800 wrote:

Jim- The time base is a 3b2 and the amp is a 3a72.
Just downloaded the complete manual from BAMA=
all 100+ pages.!!! Its going to take a while to see
if I figure out this "tool". I understood it could also
be used as a signal generator but the manual reads as if I should
already know all these things?
One of those BNC connectors must be used to input a signal to the
scope and/or output a
455khz sig. I,ve got the whole winter to play
with it.

The 560 series of scopes could use either 2 or 3 series plugins. Of
these, the 3 series were the more advanced, but the 3A72, and a few
others, are exceptions. There were several 3A7? plugins, all of which
started out as just 7? plugins, and were even more primitive that the
2 series. Consequently, the 3A7? plugins are not very desirable,
except for the 3A74, which is the only 4 channel plugin made for these
scopes.

I had to look up the 3B2 plugin. I've never seen one, but I found that
it was made to provide digital output to work with the 567 and 568
scopes. It is usually paired with the (also digital capable) 3A2,
which I've also never seen. It is only a 500 kHz plugin, however.

The 3A72 plugin only has inputs, and this is where you need to feed
the signals that you want to display on the scope.

The 3B2 has an external trigger input as well as a couple of outputs,
but you can ignore them for most uses.

I'm not familiar with the 568. I doubt if there is a 455 kHz output on
it, but I could be wrong. If it's there, then it must have something
to do with the digital display unit, which you don't have (and
probably don't want, it's just as big as the scope!)

If you want more information on these and other early Tek scopes,
including pictures of all the items we've been talking about, there is
a good book available on them. Look for "Oscilloscopes, Selecting and
Restoring a Classic" by Stan Griffiths. I believe you can find Stan on
the web and buy the book directly from him.

3 series plugins sometimes appear at swap meets for very reasonable
prices. I've paid as little as $5 for one, but then it required tubes
and repairs. I have quite a few of these, including a number of
working spares, so if you are interested in purchasing some upgrades,
I probably have them.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------