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Looking for some length of cable of the P6042 probe


benj3867
 

I am looking for some length of the p6042 current probe cable.
It again broke where the cable enters the amplifier, and it is already shortened from the last time(s) this happened that removing the bad part would make it too short.

So, if anybody has some NOS length of this cable, or some old defective probes I can use the cable of, please help!
I believe the A6302 also uses the same cable, but I may be wrong.


P.S.,
It's hard to imagine that Deane Kidd is no longer with us for 5 years now :(, If I recall correctly he had a good amount of NOS cable back in the day.


Dwayne Reid
 

Hi there.

I have the exact same problem. I grabbed a thin-diameter HDMI cable and plan to use that. Several very-good quality twisted pairs inside.

No idea how reliable it will be over the years.

dwayne

At 01:04 PM 11/8/2020, benj3867 via groups.io wrote:

I am looking for some length of the p6042 current probe cable.
It again broke where the cable enters the amplifier, and it is already shortened from the last time(s) this happened that removing the bad part would make it too short.

So, if anybody has some NOS length of this cable, or some old defective probes I can use the cable of, please help!
I believe the A6302 also uses the same cable, but I may be wrong.


P.S.,
It's hard to imagine that Deane Kidd is no longer with us for 5 years now :(, If I recall correctly he had a good amount of NOS cable back in the day.
--
Dwayne Reid <dwayner@planet.eon.net>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
780-489-3199 voice 780-487-6397 fax 888-489-3199 Toll Free
www.trinity-electronics.com
Custom Electronics Design and Manufacturing


Tom Lee
 

Except for 1:1 probes, the center conductor of probe cable is made out of resistance wire. You can't just substitute random cable for it, even if it's "high quality". That resistance is part of the magic sauce that allows probes to provide large, flat bandwidths despite the huge mismatches in impedance with which they are typically forced to interface. This was an early Tek invention (patented by John Kobbe and Bill Polits), forced by their development of high-BW scopes, where "high" was 30 millions of hertz (oops, sorry -- cycles per second), achieved by the 541. The probes had to keep up.

--Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 11/8/2020 15:54, Dwayne Reid wrote:
Hi there.

I have the exact same problem.  I grabbed a thin-diameter HDMI cable and plan to use that.  Several very-good quality twisted pairs inside.

No idea how reliable it will be over the years.

dwayne


At 01:04 PM 11/8/2020, benj3867 via groups.io wrote:

I am looking for some length of the p6042 current probe cable.
It again broke where the cable enters the amplifier, and it is already shortened from the last time(s) this happened that removing the bad part would make it too short.

So, if anybody has some NOS length of this cable, or some old defective probes I can use the cable of, please help!
I believe the A6302 also uses the same cable, but I may be wrong.


P.S.,
It's hard to imagine that Deane Kidd is no longer with us for 5 years now :(, If I recall correctly he had a good amount of NOS cable back in the day.


snapdiode
 

The P6042 is a current probe, the two coax cables inside the cable are just 50 ohm cables. For that matter, I don't see how HDMI cable can help there either.
Unless there's another kind of P6042 out there.

http://w140.com/tekwiki/wiki/P6042


Tom Lee
 

Yes, it certainly is a current probe, so good ol' coax would be just fine. Being too lazy to look up the model number, I gave generic advice that applies to passive probes (I think I said so; and I consider the 6042 a non-passive probe). And yes, it is unclear how a twisted pair would help.

--Cheers,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 11/8/2020 21:05, snapdiode via groups.io wrote:
The P6042 is a current probe, the two coax cables inside the cable are just 50 ohm cables. For that matter, I don't see how HDMI cable can help there either.
Unless there's another kind of P6042 out there.

http://w140.com/tekwiki/wiki/P6042




snapdiode
 

I am updating my CV with "Corrected Prof. T.H. Lee of Stanford on November 9 2020" under "Other accomplishments".


Tom Lee
 

You're joining a club of thousands! :)

-- Cheers,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 11/8/2020 21:20, snapdiode via groups.io wrote:
I am updating my CV with "Corrected Prof. T.H. Lee of Stanford on November 9 2020" under "Other accomplishments".




Jean-Paul
 

Bonjour if P6042 is the DC current probe with permanently attached probe/cable/amplifier, there are many fine wires to carry the AC out, hall effect etc.

They are indeed prone to breaking as thin conductors and poor strain relief.

I have a set of 6042 spare parts somewhere, as I sold or swapped my 6042 years ago,

As the cables are removed from defective units they cables may be defective but salvageable.

If you are interested, happy to search my archives and send photos.

Located in California, USA shipping is OK, international not.



Bon chance,


Jon

PS: Open to any swapping of other TEK or HP spare parts!


snapdiode
 

Sadly the P6042 is a victim of both poor cable management and plastic embrittllement.

The strain relief at the cabinet is terrible and *why* the cable did that tight turn inside the large cabinet is a mystery. The big strain relief at the probe could have just been used at the cabinet too I think. It might have looked goofy maybe.

Before I broke my probe rendering the unit useless, I wanted to create my own new cable by using the jacket and shield of some quality coax, removing the dielectric and cable, and fishing in some new wires and cables with wire-pullng lubricant.

It's doable IMO. There must also be far better strain reliefs available now.


Roy Thistle
 

On Sun, Nov 8, 2020 at 09:20 PM, snapdiode wrote:


Corrected
Maybe, in the particular case discussed...but is there more?
If I read Kobbe and Polit's patent info correctly, they claim to have invented a kind of tapered transmission line... albeit specifically for a type of oscilloscope probe.
However, this kind of transmission line was first described by R. W. Klopfenstein in 1956.


Jean-Paul
 

Ben: I recall the cable is stiff and perhaps 6', with 5 wires and 2 coax. I looked but have yet to locate, been over 20 years, but I am certain I have it.

It was intermittent at the strain relief, so cutting the ends can make it work.

I am jammed now but be patient and I will find it. Do you have any TEK spare parts, preffer to swap if possible!

Finally the 6042 had a few other weak points that I recall:
Transistors on sockets, contacts became oxidized
DC offset /zero multi-turn pot was scratchy
DC was never very stable, needed constat readjustment

Will try to locate by end of the week and send a photo.

Bon journee,



Jon


PS: I received your email but any attempt to reply bounces as do ALL yahoo.com adresses for me. Do you have a work or alternate email besides Yahoo?


Christian
 

I have made custom coax in the past using materials bought from Daburn. They will sell you all manner of (expensive) interestingly-insulated conductors, braid, and sleeving. I had to make some counterfeit twinax once with their stuff (there was a difference of opinion between two teams as to where the signal return current could flow and I had to make a protected ground and could not use triax). Sometimes you can get a couple feet of whatever as a sample, since they are the manufacturer and can just go over and cut if from the master spools.

If we could come up with enough people who need this, I've had many kinds of custom multi-conductor cable made in the past, we could get new stuff made to spec. Usually you have to go 1000' feet stateside (at $5 per and up!) but I have a shop in China that will run off 100'; they make everything but the copper strands in-house. Fascinating funnel-shaped production line.


Tom Lee
 

Hi Roy,

Those two types of lines are completely different in character, underlying philosophy and implementation. Klopfenstein's tapered line provides a broadband, low-loss equiripple match only for the specific source and termination resistance values used in its design. Kobbe and Polits designed a line with a large broadband loss in order to tolerate arbitrary termination impedances, which is the relevant situation faced by probes.

-- Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 11/9/2020 08:37, Roy Thistle wrote:
On Sun, Nov 8, 2020 at 09:20 PM, snapdiode wrote:

Corrected
Maybe, in the particular case discussed...but is there more?
If I read Kobbe and Polit's patent info correctly, they claim to have invented a kind of tapered transmission line... albeit specifically for a type of oscilloscope probe.
However, this kind of transmission line was first described by R. W. Klopfenstein in 1956.




Christian
 

While we're here, I don't suppose that anyone's ever put the transformer head from one of these in an x-ray machine to see how the Hall sensor is located/oriented relative to the ferrite material?


snapdiode
 

Yes, someone did. I heard he's handsome, humble, nice to stray animals, and has chiselled good looks.

https://groups.io/g/TekScopes/album?id=13145

There's just not that much to be learned. The secret of the Hall effect thin-film is lost to time.


Jean-Paul
 

Bonjour à tous, have designed magnetics since 1970s, and used current probes extensively.
The Tektronix are the best. Second choice is Yokogawa, but only a small range.

Both passif AC and active DC Hall Effect designs are a black art, the core magnetics and mechanical are "unobtainium".

Most defective current probes have been dropped (even a few inches) or poorly mated by gorillas.
The ferrite is custom made and mirror finish jaws, extremely thin cross section and brittle.
Like a tiny ceramic vase. Just forget fixing a damaged core or Hall effect, at the probe tip. Buying used probes off epay is a random variable. Professionals consider them a consumable item.

For the cable the OP requested, I will message him via PM

Just the ramblings of an old retired EE

Jon