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Any good? Tektronix THS720A Scope..

Hi,
Just looking on eBay there is a Tektronix hand held THS720A scope.
I`ve been after a scope for quite a while and this looks interesting.

The auction says "Each channel is isolated". I think I`ll be delving in
to amplifiers and audio equipment, I know the output stage is often not
ref'd to ground. Can anyone advise me if this scope can be used to look
at output stages and ground ref'd signals (like the amp input)?

The eBay item is 7583716250, and the URL, if your're interested is:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=7583716250&rd=1&sspagename=STRK:MESE:IT&rd=1

Also, does any one know what these scopes are generally like?

Cheers,
DannyB
 
D

Dr. Anton T. Squeegee

Hi,
Just looking on eBay there is a Tektronix hand held THS720A scope.
I`ve been after a scope for quite a while and this looks interesting.

The auction says "Each channel is isolated". I think I`ll be delving in
to amplifiers and audio equipment, I know the output stage is often not
ref'd to ground. Can anyone advise me if this scope can be used to look
at output stages and ground ref'd signals (like the amp input)?

The fact that the unit is battery powered means that the inputs
would be inherently isolated from earth ground. However, the 'ground'
side of both inputs may not be isolated from each other within the
instrument. Only the owner's or service manual could tell you that.

With that said: I would think you could easily do as you describe
with this unit. I will also add that it's kind of hard to go wrong with
Tektronix.

Granted, there are some 'scopes they've made (or marketed) that
are truly terrible in terms of serviceability, and I don't think you'll
ever see another unit from them with the versatility and long-term
durability of the 7000 series, but the one you're looking at seems like
a fine general-purpose unit.

Happy tweaking.


--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute.
(Known to some as Bruce Lane, ARS KC7GR,
kyrrin (a/t) bluefeathertech[d=o=t]calm -- www.bluefeathertech.com
"If Salvador Dali had owned a computer, would it have been equipped
with surreal ports?"
 
C

Charles Schuler

Hi,
Just looking on eBay there is a Tektronix hand held THS720A scope.
I`ve been after a scope for quite a while and this looks interesting.

The auction says "Each channel is isolated". I think I`ll be delving in
to amplifiers and audio equipment, I know the output stage is often not
ref'd to ground. Can anyone advise me if this scope can be used to look
at output stages and ground ref'd signals (like the amp input)?

If you connect the ground lead of channel 1 to some point in a circuit you
can connect the ground lead of channel 2 to another point without shorting
the two points together ... a very nice feature but also a "gotcha" for
folks who assume ground is ground and is common. In other words, when using
both channels, connect both ground leads to the appropriate reference
points. Be wary of the maximum voltage differential!

If you have never used a digital scope before, you might find this model not
to your liking. It is a fine instrument but many prefer older analog scopes
(however, they are getting to be hard to find).
 
J

Jim Yanik

The fact that the unit is battery powered means that the inputs
would be inherently isolated from earth ground. However, the 'ground'
side of both inputs may not be isolated from each other within the
instrument. Only the owner's or service manual could tell you that.

With that said: I would think you could easily do as you describe
with this unit. I will also add that it's kind of hard to go wrong with
Tektronix.

Granted, there are some 'scopes they've made (or marketed) that
are truly terrible in terms of serviceability, and I don't think you'll
ever see another unit from them with the versatility and long-term
durability of the 7000 series, but the one you're looking at seems like
a fine general-purpose unit.

Happy tweaking.

Is that model still sold in the current TEK catalog?
If not,then it's Long Term Product Support (LTPS)is 6 years after the last
time it was offered in the catalog.TEK has a list of what's currently
serviceable.www.tek.com.

The KEY is that after LTPS is over,there's NO repair service for it from
TEK.
There are NO component-level schematics or parts lists in their "service
manual",so you won't be able to fix it yourself.
Parts will NOT be available from TEK.They dispose of all exchange
assemblies and parts not common to other current models once LTPS is past.

And being a digital scope,it's calibrated by software loading in the cal
constants during the cal procedure.
TEK does them on automated cal systems.
 
T

Tom Del Rosso

Charles Schuler said:
If you have never used a digital scope before, you might find this model not
to your liking. It is a fine instrument but many prefer older analog scopes
(however, they are getting to be hard to find).

It seems so, but why did this happen so suddenly? Five years ago the
models from 25 years ago were abundant.
 
C

Charles Schuler

Tom Del Rosso said:
It seems so, but why did this happen so suddenly? Five years ago the
models from 25 years ago were abundant.

Most of the manufacturers quit making the basic analog models. Then, many
users found that they don't like digital scopes (especially the low-end
ones) and bought up, and continue to buy, the used basic analog scopes.
 
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