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Re: Tek 1A5 and 132 on eBay for 85 bucks

snapdiode
 

Weird, eBay says "This item is out of stock" instead of sold... I hope the seller didn't pull it to get a higher price elsewhere...


Re: 2445B 2467B - non Tek probes

Ozan
 

I had a P6121 that appeared to be picking up excess noise, but it was an eBay
refugee, and I assume that it was damaged somehow. Whatever the problem was it
appeared to be in the tip of the probe.
One of my ebay 6139A's had a broken connection in ground ring inside the plastic (the ring that slides onto probe). It looked OK with the probe compensation signal. I chased oscillations in a phase noise system for days until I figured out all the "oscillations" were because of missing ground lead.

Ozan


Re: Tek 576 - step generator power amp - how to check?

Ozan
 

Hi Martin,

It is interesting to test dead transistors of 576 with itself, kind of circle of life ...

For fun, I examined the defective transistors (see the pics here:
https://groups.io/g/TekScopes2/album?id=260354).
I can't see these pictures, your link points to "TekScopes2" group (note the "2" at the end). There is such a group but Is it an active group?

Ozan


Re: 465B strange ripple

Stephen
 

Here’s a little follow up on my issues with this 465B.
The attenuators (C30 to C37) are definitely not always seated properly. It seems the contacts are not optimal, and sometimes they lose them. I have to press them down a little. Not good.
Also, it seems that the trace gets much sharper when I touch the chassis ground. It’s otherwise unusually blurry.
Also, I notice that same trace ripple when I try to compensate a probe. It’s not steady at all. The trace is bouncing up and down almost like a 50-cycle hum. That is noticeable at low frequencies. At higher ones, it’s probably there too, but it’s less visually noticeable. Sometimes I see this waves within the trace itself... You can see that on the pictures I posted above.

I’ve checked all the voltages, and they are all within specs, but I think the ripple is very high.
It’s actually very hard to clearly see it, as I can’t even get a clear trace of it on the 466 I used to check it.
Unless I didn’t measure it correctly, it does seem high except on the 110V TP.

Any help you can provide will be appreciated.

Thanks in advance.


Re: Wrong cable... How bad is it?

Stephen
 

First of all, thank you all for your messages and explanations.

After making a few verifications/tests, it appears that I don’t see much difference, if at all, at lower frequencies, between a 50Ω cable and a 75Ω one. Or it’s so small that it’s negligible.
I will invest in some higher end cables though, sometimes in the future.
For now I bought a few meters of RG58 coax, and made my own cables.
It’s probably good enough for most of the stuff I do and learn at this point.
I don’t do any RF stuff. Maybe I will in the future once I’ll get my chops up.


Re: Tm500 Extender on eBay

Michael W. Lynch
 

On Tue, Feb 9, 2021 at 03:56 PM, Eric wrote:


Be careful not to plug the pluging upside down it is an easy mistake to
make with the flexible extender from tek
I will admit, I made this mistake a long time ago. The Module end of my flexible extender does not have a "key", so the module end can be reversed with "not so good" results. In my haste, I got the thing plugged in upside down, turned on the power and released the magic smoke from a module. Now I am careful to check twice and plug once.

--
Michael Lynch
Dardanelle, AR


Re: Tm500 Extender on eBay

Eric
 

Be careful not to plug the pluging upside down it is an easy mistake to
make with the flexible extender from tek

Eric

On Tue, Feb 9, 2021, 3:40 PM John Williams <books4you4@mail.com> wrote:

Received the extender yesterday. I haven’t used it yet but looks really
good so far. Excellent packaging too. Stay tuned for a user report.






Re: Tek 1A5 and 132 on eBay for 85 bucks

snapdiode
 

I have a lot of power here! Someone just snapped it up! Congratulations!

We're twins now!


Re: 2445B 2467B - non Tek probes

 

On Tue, Feb 9, 2021 at 09:30 PM, Jeff Dutky wrote:


I had a P6121 that appeared to be picking up excess noise, but it was an eBay
refugee, and I assume that it was damaged somehow. Whatever the problem was it
appeared to be in the tip of the probe.
Hi Jeff,
I don't know the exact construction of the P6121 handpiece. It's a bit different from many other Tek probe in that the ground wire connection points backward. This (inevitably, AFAICS,) results in a longer ground wire than with other probes. The ground bushing at the front is the same as on other Tek 6mm probes.
AFAIK, Tek uses a continuous bushing from the cable end to the ground bushing near the tip on all passive models. It would seem that you had a defective probe. It could be that Tek witch's hats pick up a bit more hum/noise when open than others, don't know.

The P6136, as mentioned by the OP, is a member of a well-established family of probes with practically identical construction P6131, P6133, P6136, P6138(A), P6139(A). It could be worthwhile trying to find out why the OP's probe picks up an inordinate amount of noise, under what conditions, and at which frequency range.

Raymond


Re: Tek 1A5 and 132 on eBay for 85 bucks

snapdiode
 

That's a fantastic find! I recommend anyone to snap it up! I already have these so ...


Tek 1A5 and 132 on eBay for 85 bucks

John Williams
 

Here is a 1A5 in a 132 for $85. Looks pretty nice but no pictures of it working. Still a good price.

https://www.ebay.com/itm/Tektronix-1A5-Differential-Amplifier-in-a-Tek-132-Power-Unit-Vintage/324480953564?hash=item4b8c926cdc:g:GvEAAOSws2dgIuH3


Re: 549 transformer question

ykochcal
 

Yes I totally agree,
just did not want to exclude any possibility if a core was found that was
close.

There are real cores around but not everyone has the same access to them.

Not all the uses of the core have the same physical limits. So a Different
shape core might work in a 547 but not fit in a 647.

John

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ed Breya
via groups.io
Sent: Tuesday, February 09, 2021 12:11 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] 549 transformer question

That's true John, it would be less affected by the roughness. It depends on
one's skill at working the saw and the piece, to get a somewhat decent
finish and square/plumb fit. Ed


Re: Tm500 Extender on eBay

John Williams
 

Received the extender yesterday. I haven’t used it yet but looks really good so far. Excellent packaging too. Stay tuned for a user report.


Re: 2445B 2467B - non Tek probes

 

Raymond,

I had a P6121 that appeared to be picking up excess noise, but it was an eBay refugee, and I assume that it was damaged somehow. Whatever the problem was it appeared to be in the tip of the probe. I think I swapped the BNC off of that one to another probe that had a damaged BNC connector, and put the remains in my "to be investigated later" box (or maybe I swapped the compensation box to the cable and tip from a P6122 to make a good P6121; all I seem to have in the "to be investigated later" box are P6122s).

-- Jeff Dutky


Re: 549 transformer question

Ed Breya
 

That's true John, it would be less affected by the roughness. It depends on one's skill at working the saw and the piece, to get a somewhat decent finish and square/plumb fit. Ed


Re: 549 transformer question

ykochcal
 

"but not anything involving the core leg faces"

Due to the gapping I don't think that would be true in all cases.

As long as the total gap comes out about right, and a spacers could be used
to keep the distance in a rougher cut.

some cores have a figure "8" winding on the outer legs to balance them.

The 305 gapped all three legs of the "E"

John

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ed Breya
via groups.io
Sent: Tuesday, February 09, 2021 11:09 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] 549 transformer question

If you do manage to find cores that are similar enough in size, it is
possible to sculpt a larger core down to smaller size, or to make a wider
window. Any material feature that can be attacked on a diamond wet tile saw
can be ground smaller, but not anything involving the core leg faces - you'd
need precision grinding and lapping capability to restore the finish and
fit.

Ed


Re: 2445B 2467B - non Tek probes

 

On Tue, Feb 9, 2021 at 08:08 PM, Ondrej Pavelka wrote:


The main difference I noticed was the amount of noise/interference picked
up. I was surprised because the probe cable length as well as the ground
wire length is the same
That's very strange. I am not aware of these Tek probes picking up any significant noise/interference, let alone significantly more than competitive probes. Of course, all kinds - frequencies and signal levels - of external sources may influence the signal as it comes out of the probe but again, it shouldn't be significantly worse than other probes. A 500 MHz high-impedance 10x probe's output may - and will - show more HF noise entering it than a 100 MHz 10x, of course.

Raymond


Re: TDS5054 infos...

mill_glen_chevy
 

Nope. Miguel sent a link that was suppoed to go to some posts on EEVblog, but they didn't work properly and I couldn't figure out how the software works.

--
Brian St Pierre


Re: 549 transformer question

Joel B Walker
 

As Chuck says, there probably isn't that many people in need of a new transformer. IIRC, folks were asked to send in their old transformer in order to receive a rewound one. Also, there should be plenty of duds around to get cores from. I have a couple that I know of without even looking around. As for my 549, I have ordered an original beeswax impregnated 120-0275-00 from a 564 non B off eBay to try the method described a few posts ago.


Re: Waking a slumbering 475

Mlynch001
 

On Tue, Feb 9, 2021 at 01:01 PM, Jeff Davis wrote:


. I haven't found anything better than good old trial and error to do that and
have gone through literally dozens of reels of filament in developing the
parts that I do offer
Jeff,

I do quite a bit of 3D printing myself (non-commercial and for personal use) and you have hit the nail on the head. Most of the process is very straight forward. That is until the printing starts. I find that I must do several (sometimes dozens) prints before I am able to work through the “unforeseen” issues, orientation, surface finish and the “sizing” issues. The things that most people do not see with 3D printing are those behind the scenes details that appear when the STL file goes into the slicer. There are literally hundreds (at least) of parameters available within the slicer, with an unbelievable number of possible combinations and almost all affect the outcome. I have tried to print knobs for 24xx series scopes, not much success with FDM, as you say, the details are too fine. Some things lend themselves quite well to FDM, but small and finely detailed items are particularly difficult. I would also be glad to discuss any specific questions that people might have if they want to contact me privately.

--
Michael Lynch
Dardanelle, AR

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