Date   

Re: Maybe OT? TELEQUIPMENT CT71

Dave Voorhis
 

On 11 Feb 2021, at 22:00, Roy Thistle <roy.thistle@mail.utoronto.ca> wrote:

On Thu, Feb 11, 2021 at 09:43 AM, Dennis Tillman W7pF wrote:

Owning a curve tracer like the CT71 can teach you an enormous amount about how
semiconductors of all kinds work.
Well, I hate to disagree... so to speak... but, I doubt Stephen needs a curve tracer.
That's not to say, I don't have them, or wouldn't want to buy them... but, not for the money that people want for them.
For that matter, I’d guess most of us — at least those of us who are hobbyists — don’t need any oscilloscopes, either.

I have four curve tracers — a Telequipment CT71, a Tek 577 D1, a Tek 571 (repair in progress), and a very limited one built from a £15 eBay kit.

I don’t need any of them, but I’m glad I have them. Oscilloscopes are fundamentally (but not exclusively) T vs V graphing devices. Curve tracers are fundamentally I vs V graphing devices. Having both gives a complete picture, so to speak, of electronics behaviour that only T vs V doesn’t give.

I don’t care if they’re expensive. I’ll almost invariably save money buying good kit now — even at an inflated price — than if I wait for an even higher future price, and I have the pleasure of using it now. There’s no fun in hoarding money you never spend, is there?

So you might as well buy some curve tracers with it.


Re: Tm500 Extender on eBay

Ke-Fong Lin
 

The edge connector (EDAC 307-056-500-202) is less than 8 euros at Mouser.
The extender PCB is a bit larger than usual, but a chinese fab (say JLCPCB) will probably do it.
It's probably a bit more expensive if using a US fab.
But I don't see how the PCB is going to cost more than 20 euros, even if made in the US.
So yes, $70 is a bit stiff.

To give you an idea, I've done a small project (https://github.com/anotherlin/tek_tm_ext) for a flexible TM500 extender.
The total BOM cost is less than 20 euros for sure.
JLCPCB charges around 16 euros for 5 extender PCB (ENIG).

One question for you Roy. You have mentioned a time or two that this is too
expensive. So I wonder what you would consider a fair price. It seems to me
that this is considerably cheaper than the flexible ones I have seen listed
for upwards of $250 bucks. I think at $70 that the guy making these is
probably not making a lot of money here. So please let us know what we should
be looking to pay for something like this. Thanks.


Re: Maybe OT? TELEQUIPMENT CT71

Roy Thistle
 

On Thu, Feb 11, 2021 at 09:43 AM, Dennis Tillman W7pF wrote:


Owning a curve tracer like the CT71 can teach you an enormous amount about how
semiconductors of all kinds work.
Well, I hate to disagree... so to speak... but, I doubt Stephen needs a curve tracer.
That's not to say, I don't have them, or wouldn't want to buy them... but, not for the money that people want for them.
When people told me to go play on the freeway... I learned a lot about the dynamic performance of different types of vehicles... by watching them from the freeway overpass. But, I didn't have much of a clue as to what was going on under the hood.


Re: EIP 101B Spectrum Analyzer Plug-In on E-bay

Alain Mionnet
 

Dan,

I have the ancestor of the EIP 101B , the EIP 101 since 2008 but I never taken care about this. It is in a closed frame called 201 ( the mains transformer 115/230v is inside) Below it is a pushbuton that could be the P ON (with light inside) and a BNC connector , I believe Vertical output.(that is Lin or log scale for the detector)
1 years ago I wanted try to know about this and find nothing. In last january I found it really by a big chance, intrigued by "the third party section" , with the front picture that is very close !
Mine is not also beautiful that on the wiki page...but the inside is not so bad and complete.
So does Dan have the EIP 101B on ebay above?
I will give more informations soon.The plug-in have the same size and is similar mechanicaly et with the rear connector.
It is 2 EIP identification plates, one on the frame box and one on the plug-in.I have not the 2 center N connectors below and with the link between.
Some ICs have no marking.
I know a microwave engineer who was in EIP, Phase Matrix and still in NI but his last publication is from 3 years ago. I'm afraid that he is retired because I think it was the time.


Alain

France


Re: Tm500 Extender on eBay

John Williams
 

One question for you Roy. You have mentioned a time or two that this is too expensive. So I wonder what you would consider a fair price. It seems to me that this is considerably cheaper than the flexible ones I have seen listed for upwards of $250 bucks. I think at $70 that the guy making these is probably not making a lot of money here. So please let us know what we should be looking to pay for something like this. Thanks.


Re: 7104 out of focus/astigmatism

Francesco Franzini
 

Just more detail on the issue..

I noticed something strange, especially on readout trace, during the warm up, i see the trace intensity pulsating and moving a little bit (seems modulated), also this issue goes away after the warm up.

Results of the tests:
HV level (all of them) are stable, with no variation during the warm up, unfortunately i do not have any HV probe for oscilloscope to check the waveforms as per service manual, i tried with cooling spray selectively on the HV components with no luck.
All connections seems to be good, everything is clean and in good shape, i haven't found any corrosion or issue on the connector.

Since the issue last almost 30 min I will continue to check the low voltage level to see if i found something wrong.

Francesco


Re: Maybe OT? TELEQUIPMENT CT71

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.


Re: TM50X DC ripple?

Roy Thistle
 

On Thu, Feb 11, 2021 at 11:19 AM, Jared Cabot wrote:


Allowable ripple is specified in the Tek TM500 mainframe tester manual, shown
in the tables.
Yes... but the following warning appears whenever the give them: "These voltages are quite dependent on line voltage and are sensitive to line voltage waveform distortion."
So are they really "specified?"
Probably why the specs use PARD in the actual TM506 instruction manual?


Re: 2465B CH1,2 compression

Jean-Paul
 

Hello all

I Swapped just CHAN 1,2 switch hybrids from another scope with Maxtek Hybrids, 1994 that is 100% OK.

Chuck Harris was indeed correct, U500 IS BAD causing the distortion. Was orig TEK dated 1991.

Need to get a 155-0236-00 Channel Switch IC

Bon Journee,


Jon


Re: Waking a slumbering 475

Roy Thistle
 

On Thu, Feb 11, 2021 at 01:28 AM, Jeff Dutky wrote:


in order to exercise the LOW LINE indicator.
Yes; but that's to test the lower limit of the specified AC voltage range. (Not to go significantly lower than that limit. Is it not?)
PARD testing on SMPS and linear, uses a variable AC line voltage source... like a Variac autotransformer... to test for tolerance within the specified line input range... but not below it.


Re: Maybe OT? TELEQUIPMENT CT71

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.


Re: Looking for 067-0625-00 Peak-to-Peak Detector Photos

Gudjon Gudjonsson
 

Hi Jared and Dan

There is an older discussion with link to photos on the forum
https://groups.io/g/TekScopes/topic/tektronix_067_0625_00_peak_to/27735549?p=Created,,,20,1,0,0

Regards
Gudjon


Re: Maybe OT? TELEQUIPMENT CT71

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.


Re: Looking for 067-0625-00 Peak-to-Peak Detector Photos

Dan G
 

Hi Jared,

I can upload photos of mine to TekWiki, if you'd like. I can take pictures of both sides
of the PCB, but I am not prepared to open or otherwise disturb the RF cavity.


dan


Looking for 067-0625-00 Peak-to-Peak Detector Photos

Jared Cabot
 

Hi all,
I'm thinking of building my own version of the 067-0625-00 Peak-to-Peak Detector, and I am hoping someone has one that they can take a few decent photos of each side (maybe even with a ruler for scale) so I can get a reference of the Tek design to construct mine from.

Any help will be greatly appreciated. :)


Thanks!
Jared.


Re: TM50X DC ripple?

Jared Cabot
 

Allowable ripple is specified in the Tek TM500 mainframe tester manual, shown in the tables.

https://w140.com/tekwiki/wiki/067-1201-99


Re: Maybe OT? TELEQUIPMENT 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


Re: Waking a slumbering 475

stevenhorii
 

I think what happens on eBay is that if a seller plugged a piece of
equipment in and nothing happens, they list it as “untested”. Others are
more honest and say “powers on - no other testing done” or “does not power
on - parts only”.

I have had experiences both ways with Tek equipment on eBay. A 7A26 plug-in
that was described as “powers on - displays a trace, no other testing
done”. It worked in my 7844 for about a minute before one of the tantalums
self-destructed (unfortunately taking adjacent parts with it and burning
the underlying circuit board). It certainly may have been tested but for a
very short time. Other times, I bought a couple of plug-ins (7B92A and a
7A24) that were described as “parts only”. However when put in my scope,
they both worked fine. A quick performance test of the 7B92A showed that it
was either in calibration or close to it (though I did not do all the tests
- I primarily was looking at sweep speed accuracy against a high-precision
quartz frequency standard). The 7A24 worked fine, but I would not have done
any quantitative stuff with it without calibrating it.


On Thu, Feb 11, 2021 at 13:24 Roy Thistle <roy.thistle@mail.utoronto.ca>
wrote:

On Wed, Feb 10, 2021 at 07:36 AM, Torch wrote:


Before giving it to me, the owner plugged it in and turned it on
That's usually what inexperienced sellers do with these old Tek scopes
(unless you can catch them before they do it.)
If it's working, I suppose they figure, they can ask more for it.
But, if it gets killed, it probably goes into the garbage, or sells for a
lot less.
I'd say, if you got one (buyer or seller)... don't plug it in, until you
check it out.






Re: 465B strange ripple

Stephen
 

On Thu, Feb 11, 2021 at 07:01 AM, n4buq wrote:


Stephen,

I don't know if this has already been considered, but do you see that ripple
with the input switch set to GND for the channel you've selected?

Thanks,
Barry - N4BUQ
Hi Barry,

I’m not in front of it at the moment, but as far as I can remember, no.


Re: 7104 out of focus/astigmatism

Francesco Franzini
 

Thank you both for your advice, i will get back with the results !!!

I realize that is didn't explained very well the issue, the oscilloscope goes out of focus/astigmatism slowly and constantly, and slowly and constantly recover focus and astigmatism, and at any point of this "process" working with focus and astigmatism setting i am able to have perfect trace and readout.

Francesco

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