2445B 2467B - non Tek probes


Ondrej Pavelka
 

Hi folks,

I have 2445B for quite many years, thanks to this awesome group and some super helpful members like Siggy or Chuck and others I dealt with leaky caps on the A5 board, backed up and copied calibration over. It's all good and I can't really be happier. Well except I just acquired 2467B in basically new condition. The only problem I have the P6136 probes becoming brittle and falling apart. The 2467B came with two Testek 600MHz probes but as much as I could live without the ID button, not having the coded ring is a nightmare when swapping between probes.
Anyone on here managed to 3D print or make in any other way adapter which would make the probe coded? I can clearly see the Testek probes are superior to P6136 but the lack of the coding ring is driving me mad. I was swapping between coded and unconditional probes during one calibration of an instrument and guess what..... Yes I completely ruined the calibration and had to redo the entire 6 hour process again......

Any way to convert the Testek probes oris there a pass through adapter to make the probe coded?
I didn't really appreciate the ingenuity of the coded probes up until I lost it.


 

On Tue, Feb 9, 2021 at 12:54 AM, Ondrej Pavelka wrote:


I can clearly see the Testek probes are superior
to P6136 but the lack of the coding ring is driving me mad.
I couldn't find 600 MHz Testec (Testek?) passive probes, 500 MHz being the max. What did you find that makes the Testek probes superior to P6136's? Are you talking about the (1.2 GHz) active ones?

In most cases, it doesn't make much sense to use any passive probe at these high frequencies, because of their large input capacitance of around 10 pF min. I don't know any passive 1:10 probes spec'ed higher than 500 MHz.

Tek P6137's aren't very expensive and recommended for the 2465B/67B. I guess that makes more sense than trying to add a readout feature.

Raymond


Harvey White
 

The passive probe pin for readout scaling requires an offset pin.  Electrically it's a resistor to ground.  I haven't seen any replacement BNC connectors like that, so you'd have to adapt an existing probe box with the proper resistor to the task.  Dead 6xxx probes with readout pins are relatively common, so you could redo the box with a BNC on one end, and the existing BNC (and pin) on the other.

Harvey

On 2/8/2021 6:54 PM, Ondrej Pavelka wrote:
Hi folks,

I have 2445B for quite many years, thanks to this awesome group and some super helpful members like Siggy or Chuck and others I dealt with leaky caps on the A5 board, backed up and copied calibration over. It's all good and I can't really be happier. Well except I just acquired 2467B in basically new condition. The only problem I have the P6136 probes becoming brittle and falling apart. The 2467B came with two Testek 600MHz probes but as much as I could live without the ID button, not having the coded ring is a nightmare when swapping between probes.
Anyone on here managed to 3D print or make in any other way adapter which would make the probe coded? I can clearly see the Testek probes are superior to P6136 but the lack of the coding ring is driving me mad. I was swapping between coded and unconditional probes during one calibration of an instrument and guess what..... Yes I completely ruined the calibration and had to redo the entire 6 hour process again......

Any way to convert the Testek probes oris there a pass through adapter to make the probe coded?
I didn't really appreciate the ingenuity of the coded probes up until I lost it.





 

Harvey, Ondrej,

I've had a lot of success merely swapping the BNC assembly (hex nut and BNC with readout pin in the plastic shell) from one probe box to another. I've done this successfully for P6121s, P6131s, and P6106s, using similar (otherwise damaged) probes as the donors. The scale resistor, at least, seems to reside entirely in the plastic housing around the BNC connector.

I have NOT tried this with any probes that have the ID function.

-- Jeff Dutky


 

Ondrej,

I've been looking at the very nice passive probes manufactured by Probe Master, as replacements for Tek's P6075A, P6106, and P6131, as they offer probes with the right specs that also have a scale readout pin. Tyrosys and CalTest also offer probes with readout pins, and the prices seem reasonable.

-- Jeff Dutky


Harvey White
 

Right, if you mean the entire box, then that has the compensation network in it.  If you mean just unscrewing the BNC connector and transplanting that, the resistor is about a 1/10th watt resistor hidden in the probe innards.  It is possible to take the probe apart and gain access to that resistor.  At the moment I don't remember exactly how, but the BNC plastic shell is NOT molded in place and can be removed.

IIRC, the ID function is in the probe itself, and shorts an additional wire to ground, (try shorting the ring to ground at the scope end).

What the plugin does is up to it (move trace, "identify" or ground trace....

Harvey

On 2/8/2021 8:45 PM, Jeff Dutky wrote:
Harvey, Ondrej,

I've had a lot of success merely swapping the BNC assembly (hex nut and BNC with readout pin in the plastic shell) from one probe box to another. I've done this successfully for P6121s, P6131s, and P6106s, using similar (otherwise damaged) probes as the donors. The scale resistor, at least, seems to reside entirely in the plastic housing around the BNC connector.

I have NOT tried this with any probes that have the ID function.

-- Jeff Dutky





 

Harvey,

I have been trying to figure out how to remove the plastic shell on the BNC connector and have not had any luck, even where i have connectors that are partly disintegrated. Maybe I have simply been too gentle in my investigations. If you can recall how this is done, I would be eager to know.

-- Jeff Dutky


 

Also, I know that some folks don't want to shell out for brand new probes, either out of budget, or out of a desire to keep the scope "genuine" (or because the probes that Tek made for the scope have the right capacitance for the scope). I have, thus far, had remarkable good luck buying second hand probes from eBay, despite both evident mishandling by the sellers (cables too tightly wound or folded), and clear advertisement as being non-working (e.g. a P6106 whose tip end and been replaced with an SMA connector, appeared to be completely defunct when I first tested it. I decided to use it as a donor for another probe with a damaged BNC connector, and while disassembling it I discovered that the cable was unseated in the compensation box. I reseated the cable end and now it works like a charm!)

My advice, if you really want original Tek probes to go with your Tek scope, is to try your luck on eBay. So long as you are spending a lot less than what Probe Master or CalTest charge it seems like there's a fair chance of success.

I will say, however, that the subminiature probes, like the P6131 that goes with the 2465, and the 6137 for the 2465B, seem much more fragile than the earlier modular probes. I've seen a lot of P6131s for sale on eBay that either have broken probe tips, or where the tip assembly is missing altogether. Putting together four good P6131s was much more challenging (and expensive) than putting together six good probes of earlier models (1 pair P6075As, 1 pair of P6106s, and one pair of P6121s). Also, the witches hats for the subminiature probes seem almost impossible to find.

-- Jeff Dutky


Jean-Paul
 

Bonjour a tous::

Since 1970s have used all types of probes and accumulated a huge collection, TEK, and other brands.
The TEK are by far the best in function, specs, ruggedness and reliability. Even HP and Yokogawa probes cannot compare.
I cannot comment on the third party brands , but if they are Chinese clones, I would think they are poorly made and not for serious use.
"Penny wise and Pound Foolish"

2465/7/B have BW 300-350-400 MHz and specify P6137 for the BW mentioned.
Even if an off brand compensates the input capacitance, as mentioned the probe ID and multiplier resistor will be wrong.
I have found the correct probes on epay and Ham fleas in the past, I would suggest patience and keep looking out for the specified probes.

As mentioned, 10X probes are in general not accurate for wideband use as the self capacitance and ground clip inductance affect the observed waveform.
We use either 50 Ohm coax direct to the scope or the very fine Tek Zo probes such as P6156.

Suggest to read the TEK Circuit concepts book "Oscilloscope Probes" for probe considerations and technique.

Just the ramblings of an old retired EE!

Bon Chance,

Jon


Roy Thistle
 

On Mon, Feb 8, 2021 at 10:33 PM, Jeff Dutky wrote:


My advice, if you really want original Tek probes to go with your Tek scope,
is to try your luck on eBay.
There is only one other market that is "......" than paybay, and that's utube. (Where "......" is a word egregiously disparaging in meaning.)
Like penny stock pumpers... there are those, on both, working hand-in-hand to manufacture bogus value from flumadiddle.
That's my opinion, and I'm sticking to it.


Mark Litwack
 

Hi Jeff,

The plastic housing around the BNC pulls off. It's a tight fit but it will come off.

Inside you will find the pin, a spring, and a MELF resistor that are all held in place by the housing. They will fall out once you get the housing off, so be careful not to let them roll away on you.

-mark

On Mon, Feb 8, 2021 at 10:47 PM, Jeff Dutky wrote:

Harvey,

I have been trying to figure out how to remove the plastic shell on the BNC
connector and have not had any luck, even where i have connectors that are
partly disintegrated. Maybe I have simply been too gentle in my
investigations. If you can recall how this is done, I would be eager to know.

-- Jeff Dutky


Harvey White
 

I tried to find the one that I had taken apart, but without success.

I think that there are two types, possibly distinguished by the plastic color.

The one that I remember was light gray.  The plastic was in two pieces, the body and a ring at the end.  I seem to remember that the ring can be pried off.  Once that is done, the mechanical parts can simply be pushed out.

The second one that I just looked at was a black plastic.  In this case, the body apparently had the ring permanently attached. There are a number of small fingers that grab the back of the metal insert.  I suspect that you can just push out the connector using a defunct panel mount BNC shell.

Harvey

On 2/8/2021 10:47 PM, Jeff Dutky wrote:
Harvey,

I have been trying to figure out how to remove the plastic shell on the BNC connector and have not had any luck, even where i have connectors that are partly disintegrated. Maybe I have simply been too gentle in my investigations. If you can recall how this is done, I would be eager to know.

-- Jeff Dutky





Ondrej Pavelka
 

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

On Tue, 9 Feb 2021, 01:17 Raymond Domp Frank, <hewpatek@gmail.com> wrote:

On Tue, Feb 9, 2021 at 12:54 AM, Ondrej Pavelka wrote:


I can clearly see the Testek probes are superior
to P6136 but the lack of the coding ring is driving me mad.
I couldn't find 600 MHz Testec (Testek?) passive probes, 500 MHz being the
max. What did you find that makes the Testek probes superior to P6136's?
Are you talking about the (1.2 GHz) active ones?

In most cases, it doesn't make much sense to use any passive probe at
these high frequencies, because of their large input capacitance of around
10 pF min. I don't know any passive 1:10 probes spec'ed higher than 500 MHz.

Tek P6137's aren't very expensive and recommended for the 2465B/67B. I
guess that makes more sense than trying to add a readout feature.

Raymond






Ondrej Pavelka
 

Sorry the 600 was a typo it's the 500MHz probes it came with.

On Tue, 9 Feb 2021, 01:17 Raymond Domp Frank, <hewpatek@gmail.com> wrote:

On Tue, Feb 9, 2021 at 12:54 AM, Ondrej Pavelka wrote:


I can clearly see the Testek probes are superior
to P6136 but the lack of the coding ring is driving me mad.
I couldn't find 600 MHz Testec (Testek?) passive probes, 500 MHz being the
max. What did you find that makes the Testek probes superior to P6136's?
Are you talking about the (1.2 GHz) active ones?

In most cases, it doesn't make much sense to use any passive probe at
these high frequencies, because of their large input capacitance of around
10 pF min. I don't know any passive 1:10 probes spec'ed higher than 500 MHz.

Tek P6137's aren't very expensive and recommended for the 2465B/67B. I
guess that makes more sense than trying to add a readout feature.

Raymond






 

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


 

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


 

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


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


 

Ozan wrote:

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.
Yes, that sounds very familiar: I had a dirty ground connection on a 45 year old probe I inherited with one of my father's scopes. Everything cleared up when I pulled the ground lead and cleaned the spring clips thoroughly. Sadly, the construction of the P6120/21/22 probes makes this kind of fix extremely difficult, if not impossible.

If I had better understood how probes were matched to instruments (and been familiar with the recommendation matrix in the Tek catalogs) I could have simply standardized on P6105s and P6106s for all my scopes (except for the 2465) and been a slightly wealthier man today.

-- Jeff Dutky


Ondrej Pavelka
 

I'm very pleasantly surprised, I written to Testec whether there is a way
to swap connectors from non coded to coded and they replied there isn't but
they like people who fix old oscilloscopes and synthesisers and they will
send me one of their coded 500MHz probes for free!

On Wed, 10 Feb 2021, 01:49 Jeff Dutky, <jeff.dutky@gmail.com> wrote:

Ozan wrote:

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.
Yes, that sounds very familiar: I had a dirty ground connection on a 45
year old probe I inherited with one of my father's scopes. Everything
cleared up when I pulled the ground lead and cleaned the spring clips
thoroughly. Sadly, the construction of the P6120/21/22 probes makes this
kind of fix extremely difficult, if not impossible.

If I had better understood how probes were matched to instruments (and
been familiar with the recommendation matrix in the Tek catalogs) I could
have simply standardized on P6105s and P6106s for all my scopes (except for
the 2465) and been a slightly wealthier man today.

-- Jeff Dutky