Topics

Maybe OT? TELEQUIPMENT CT71


Stephen
 

What do you guys think of this curve tracer compared to other “real” Tek ones?
What would it compare to in the official Tek line? Is it worth it?
I’ve never used a curve tracer before, and I don’t own one, I’m just curious.


-
 

Link? FWIW Hameg also makes or made a scope that had a built in curve
tracer. But I don't thinkit was more than one of the basic octopus style
CTs that was added to a regular scope. I'm sure it would work but it
wouldn't be as versatile or have as many controls as a 575, 576, 577.

On Wed, Feb 10, 2021 at 4:55 PM Stephen <stephen.nabet@gmail.com> wrote:

What do you guys think of this curve tracer compared to other “real” Tek
ones?
What would it compare to in the official Tek line? Is it worth it?
I’ve never used a curve tracer before, and I don’t own one, I’m just
curious.






 

According to the manual here (https://w140.com/tekwiki/images/8/83/070-1075-00.pdf) "TELEQUIPMENT is a registered trade mark of TEKTRONIX U.K. LTD." so it would seem to be as "real" a piece of Tek equipment as there ever was.


Stephen
 

On Wed, Feb 10, 2021 at 11:01 AM, - wrote:


Link?
https://w140.com/tekwiki/wiki/Telequipment_CT71


Stephen
 

On Wed, Feb 10, 2021 at 11:04 AM, Jeff Dutky wrote:


According to the manual here
(https://w140.com/tekwiki/images/8/83/070-1075-00.pdf) "TELEQUIPMENT is a
registered trade mark of TEKTRONIX U.K. LTD." so it would seem to be as "real"
a piece of Tek equipment as there ever was.
Yes I agree with you , but according to TekWiki, Telequipment was originally a British company acquired by Tektronix. So how much was Tektronix really involved...?


Dave Voorhis
 

On 10 Feb 2021, at 21:54, Stephen <stephen.nabet@gmail.com> wrote:


What do you guys think of this curve tracer compared to other “real” Tek ones?
What would it compare to in the official Tek line? Is it worth it?
I’ve never used a curve tracer before, and I don’t own one, I’m just curious.
I have one.

It has neither the range of features or the industrial build quality (or the storage capability) of my Tek 577 D1, but it’s still a nice, capable curve tracer.

On the plus side, it has an illuminated graticule, which my 577 doesn’t have.


Stephen
 

On Wed, Feb 10, 2021 at 11:32 AM, Dave Voorhis wrote:


On 10 Feb 2021, at 21:54, Stephen <stephen.nabet@gmail.com> wrote:


What do you guys think of this curve tracer compared to other “real” Tek
ones?
What would it compare to in the official Tek line? Is it worth it?
I’ve never used a curve tracer before, and I don’t own one, I’m just
curious.

I have one.

It has neither the range of features or the industrial build quality (or the
storage capability) of my Tek 577 D1, but it’s still a nice, capable curve
tracer.

On the plus side, it has an illuminated graticule, which my 577 doesn’t
have.

Storage?
What kind of features would you say it’s lacking?
Build quality isn’t good? From the pictures it looks like any other good Tek gear to me.


Dave Voorhis
 

On 10 Feb 2021, at 22:41, Stephen <stephen.nabet@gmail.com> wrote:


On Wed, Feb 10, 2021 at 11:32 AM, Dave Voorhis wrote:


On 10 Feb 2021, at 21:54, Stephen <stephen.nabet@gmail.com> wrote:


What do you guys think of this curve tracer compared to other “real” Tek
ones?
What would it compare to in the official Tek line? Is it worth it?
I’ve never used a curve tracer before, and I don’t own one, I’m just
curious.

I have one.

It has neither the range of features or the industrial build quality (or the
storage capability) of my Tek 577 D1, but it’s still a nice, capable curve
tracer.

On the plus side, it has an illuminated graticule, which my 577 doesn’t
have.

Storage?
What kind of features would you say it’s lacking?
Build quality isn’t good? From the pictures it looks like any other good Tek gear to me.
Telequipment that was owned by Tektronix from the late 60’s through the 1970’s, I think. They made relatively low-cost equipment targeted at the service market, rather than the higher-end engineering market targeted by Tek.

Some differences:

The CT71 is technically simpler than the 577 and generally light-weight construction and cheaper circuit boards, lower power (10 watts max compared to the 577’s 100 watts), and a fixed front-end with multiple device adaptors, instead of a front-end plug-in (several available) with multiple device adaptors on the 577.

The 577 has a multi-turn precision vernier for offset and switchable aid/oppose, whereas the CT71 is a standard 1-turn pot and aid-only.

The 577 is switchable 1 - 10 or 1 - 100 (?) steps; the CT71 is 1 - 10 steps only.

The 577 has single-sweep and pulsed modes, which the CT71 doesn’t have.

The 577 D1 (but not the D2 model) has analog storage, which reduces flicker with slow sweeps and allows you to easily observe curve shift over time due to heating and such, which the CT71 doesn’t have.

The 577 has a front-panel circuit breaker to cut out the collector supply if the DUT is shorted; with the CT71 you replace a fuse.

Etc.


Stephen
 

Thank you Dave. Good points.
Is it still worth getting?


Tim Phillips
 

from Tim P (UK)

I have a CT71, although, for me, it is used mainly for checking Tunnel
Diodes.
It's certainly adequate as a go / no-go tester, and will show the switching
current.

Tim


Tim

On Wed, 10 Feb 2021 at 23:28, Stephen <stephen.nabet@gmail.com> wrote:

Thank you Dave. Good points.
Is it still worth getting?






Stephen
 

On Wed, Feb 10, 2021 at 09:04 PM, Tim Phillips wrote:


from Tim P (UK)

I have a CT71, although, for me, it is used mainly for checking Tunnel
Diodes.
It's certainly adequate as a go / no-go tester, and will show the switching
current.

Tim
From what you guys are saying, it’s ok, but nothing to write home about. Is getting a 7CT1N a better option?


Jean-Paul
 

Hello all,

If the Tele equipment is low cost, and precision and ranging are satisfactorily, suggesting go for it.

If you need more serious measurement, over wide range, reccomend 576 and 577 are best, but costly and hard to ship. Finally the 7CT1N 7000 plug-in is a compromise, smallest size and uses existing mainframes.

Bon Chance


Jon


Dave Voorhis
 

I think it's a good piece of a kit. If the price is right, buy it.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Stephen
Sent: 10 February 2021 23:29
To: TekScopes@groups.io
Subject: Re: [TekScopes] Maybe OT? TELEQUIPMENT CT71

Thank you Dave. Good points.
Is it still worth getting?


 

Hi Stephen,
The CT71 is a perfectly acceptable curve tracer. Tektronix acquired Telequipment to offer lower cost scopes to customers who could not afford, or did not need, the laboratory quality scopes that Tek made.

I had a chance to use the CT71 at the vintageTEK museum a little over a year ago to see if it would work with my Vacuum Tube Curve Tracer adapter. It worked perfectly well. The triode and pentode curves it displayed were exactly the same as I got on a 575, 576, and 577.
I did not have a chance to do a side by side comparison of the CT71 with the other Tek curve tracers but from its specs it is better than a 575 and it is much smaller.

Owning a curve tracer like the CT71 can teach you an enormous amount about how semiconductors of all kinds work. The only thing that was different on the CT71 was the way you connected the transistor, diode, etc. to it. It doesn't have the three banana jacks that are common to all of the Tek curve tracers. Instead it has binding posts. That means you won't be able to use Tek transistor adapters on it, but since it already has sockets in addition to its binding posts that should not be a problem at all.

At one point in my career I used one of the Telequipment dual-trace scopes for about a year once I discovered they had one important advantage over the Tektronix scope I had been using at the time. In a Tek scope a signal is clamped as soon as it goes off screen so it won't go any further. There is nothing wrong with doing this in most cases since the user doesn't need to know what happens off screen. But if you are adding two signals together by using A+B and inverting the B signal then it would be nice to be able to keep increasing the sensitivity of each channel to show more detail about the differences in both signals. You can't do this with a Tek scope since as you increase the sensitivity of each channel they are actually going so far off screen before they are added together (which would bring them back on-screen) that they have been clamped.

The Telequipment vertical amplifier used different circuitry which allowed the signal to go way off screen which was an important difference because their vertical amplifier was able to recover much faster when I applied wild voltage swings to it from a D to A converter I was testing for its settling time as it was forced to go from its maximum positive output to its maximum negative output then back to zero. No matter how far off screen I drove the signal on the Telequipment scope it was able to return back to zero faster than the D/A converter so I could measure the D/A's settling time. The Tek scope took so long to recover once the trace went off-screen that the A/D was already settled at 0V when the trace returned on-screen.

The lesson I learned that year was that Tek scopes are not necessarily the very best scopes made. There are pros and cons to every scope and it is important to understand the requirements of the measurement you need to make so you select the right instrument to measure it.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Stephen
Sent: Wednesday, February 10, 2021 1:55 PM
To: TekScopes@groups.io
Subject: [TekScopes] Maybe OT? TELEQUIPMENT CT71

What do you guys think of this curve tracer compared to other “real” Tek ones?
What would it compare to in the official Tek line? Is it worth it?
I’ve never used a curve tracer before, and I don’t own one, I’m just curious.







--
Dennis Tillman W7pF
TekScopes Moderator


Stephen
 

Merci Jon.


Stephen
 

Dennis,

This is very interesting indeed. I’ve been thinking about acquiring a curve tracer for a while now, but they’re not quite as available for sale in Europe as they are in the US. And they’re quite expensive, even without shipping....
So when I found this CT71 locally, I was interested in knowing more about it. I will be using it also for tubes. So I’ll make an adapter and a separate power supply for that....
I don’t know what a fair price would be for one of these CT71...


 

Hi Stephen,
It won't be easy to decide on a fair price since you are in Europe and since the CT71 is not very common. In the US a fair price for a 575 is somewhere between free and $100. A 576 is close to $1,000, a 577 is usually less than a 576.
If you are planning on testing tubes I suggest you read the paper I wrote on testing vacuum tubes with a curve tracer. It explains in great detail how to do it. I will send a copy to you at your email address.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Stephen
Sent: Thursday, February 11, 2021 9:54 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Maybe OT? TELEQUIPMENT CT71

Dennis,

This is very interesting indeed. I’ve been thinking about acquiring a curve tracer for a while now, but they’re not quite as available for sale in Europe as they are in the US. And they’re quite expensive, even without shipping....
So when I found this CT71 locally, I was interested in knowing more about it. I will be using it also for tubes. So I’ll make an adapter and a separate power supply for that....
I don’t know what a fair price would be for one of these CT71...







--
Dennis Tillman W7pF
TekScopes Moderator


Dave Voorhis
 

On 11 Feb 2021, at 17:54, Stephen <stephen.nabet@gmail.com> wrote:

Dennis,

This is very interesting indeed. I’ve been thinking about acquiring a curve tracer for a while now, but they’re not quite as available for sale in Europe as they are in the US. And they’re quite expensive, even without shipping....
So when I found this CT71 locally, I was interested in knowing more about it. I will be using it also for tubes. So I’ll make an adapter and a separate power supply for that....
I don’t know what a fair price would be for one of these CT71...
Mine was £40 from eBay, via an accepted “Make offer.”

I’ve seen a few CT71’s subsequently come up for auction and go for, if I recall correctly, well over £100.


Stephen
 

On Thu, Feb 11, 2021 at 08:51 AM, Dave Voorhis wrote:

Mine was £40 from eBay, via an accepted “Make offer.”

I’ve seen a few CT71’s subsequently come up for auction and go for, if I
recall correctly, well over £100.
They want 400€ for it. I guess I wouldn’t pay over 200€, and that’s already a lot I guess.


Roy Thistle
 

On Wed, Feb 10, 2021 at 02:04 PM, Jeff Dutky wrote:


TELEQUIPMENT... so it would seem to be as "real" a piece of Tek equipment as there ever was.
I get them, sometimes, when I can get them for very little. (I'm talking about Telequipment oscilloscopes.)
Here in the colonies, lower end Telequipment scopes seem a fav of the audio service/audiophile types.
They're not junk; but they're not Tek quality either.
Often I can get... or have got, a Tek 5000 series scope, for little more.
And those, for band limited audio work, are much better oscilloscopes.