Test Equipment Anonymous (TEA) group therapy thread

[BU508A]

Received today some tools from Wiha.

A side cutter, because the one I have already suffered a little bit from *cough* abusing *cough*.

And this nice Allen set (Inbus in German).

The side cutter is a Wiha Z 40 0 03 118 (27388) and the Allen set a Wiha 369H11 (36453).



I've also assembled an H-field probe. For this, I've used some semi-rigid cable which I've bought second hand last year at the UKW Tage in Weinheim. The white tape around it is some Teflon tape for the insulation. It is the same type of Teflon tape which can be found in a hardware store as a sealing tape for plumbing.



I did not calibrate it, because I just want to check if something is going on. Useful for some repairs.
This is a screenshot of the magnetic field of a toroidal choke of a Joule thief. Built one a while ago as a little torch. The oscillator runs at around 338kHz at 0.84V.

[Cerebus]

I have stayed away from Raspberry in droves for just that reason. If I wanted to run a version of *NIX even more castrated than android, on essentially a 10-year-old android Pwn without all the portability or a decent screen or usable touch interface... well, okay, I've never actually gotten past the "10-year-old android Pwn" part, so...

I just don't see the excitement; get a 10-year-old Dell PC at the Thrift for $10 and you have the same thing and another $30-50 in your pocket. 

mnem
*couch-tuber-time widda fam*

Eh? If you're implying that the OS on the Pi is a castrated Unix you're rather off the mark. The default is to run Raspbian (now inexplicable renamed Raspberry Pi OS) which is just the current version of Debian stable (buster at time of writing) built for ARM with hardware floating point. Nothing castrated about it, it's just vanilla Debian, the same as I've been running on my own servers for 15 years since I migrated off of Solaris.

There's also three flavours of Ubuntu, LibraELEC, OSMC, a handful of oddities and now a stable RiscOS, and as of a couple of weeks ago an experimental, official VMWare ESXi 7.0.0

[Kosmic]

I've also assembled an H-field probe. For this, I've used some semi-rigid cable which I've bought second hand last year at the UKW Tage in Weinheim. The white tape around it is some Teflon tape for the insulation. It is the same type of Teflon tape which can be found in a hardware store as a sealing tape for plumbing.

Teflon is a really good rf shield. If you want your probe to act a little bit like an antenna, I would not cover the tip of the probe with Teflon tape.

[BU508A]

I've also assembled an H-field probe. For this, I've used some semi-rigid cable which I've bought second hand last year at the UKW Tage in Weinheim. The white tape around it is some Teflon tape for the insulation. It is the same type of Teflon tape which can be found in a hardware store as a sealing tape for plumbing.

Teflon is a really good rf shield. If you want your probe to act a little bit like an antenna, I would not cover the tip of the probe with Teflon tape.

Oh!

Upsi, wasn't aware of that. How about Kapton tape? Would that be any better?

And, btw, do you know why Teflon is acting like a good RF-shield?

[Kosmic]

I've also assembled an H-field probe. For this, I've used some semi-rigid cable which I've bought second hand last year at the UKW Tage in Weinheim. The white tape around it is some Teflon tape for the insulation. It is the same type of Teflon tape which can be found in a hardware store as a sealing tape for plumbing.

Teflon is a really good rf shield. If you want your probe to act a little bit like an antenna, I would not cover the tip of the probe with Teflon tape.

Oh!

Upsi, wasn't aware of that. How about Kapton tape? Would that be any better?

And, btw, do you know why Teflon is acting like a good RF-shield?

Kapton is also a really good isolator. Maybe just paint the tip of the probe ? Or use heatshrink ?

For Teflon, the dielectric constant is really low. Often used inside coax cables as isolator.

[Cerebus]

Teflon is a really good rf shield. If you want your probe to act a little bit like an antenna, I would not cover the tip of the probe with Teflon tape.

Another "Eh?". Why do you think that? Teflon is a dielectric, they make capacitors out of it. If it acted as an RF shield I think I'd have heard about it before now and I don't think the capacitors would work very well.

[Kosmic]

Teflon is a really good rf shield. If you want your probe to act a little bit like an antenna, I would not cover the tip of the probe with Teflon tape.

Another "Eh?". Why do you think that? Teflon is a dielectric, they make capacitors out of it. If it acted as an RF shield I think I'd have heard about it before now and I don't think the capacitors would work very well.

I have no idea how teflon capacitors are constructed. But the dielectric constant of teflon being really low, resistance is really high and leakage is low. Teflon wires are often used when trying to protect sensible signal from EMI.

Try to make a antenna with a piece of teflon wire for fun. It's not going to work really well

Edit: Ok, I think I'm mixing up good electrical properties and being resistant to electromagnetism. Technically Teflon should be transparent to RF.

[Cerebus]

Teflon is a really good rf shield. If you want your probe to act a little bit like an antenna, I would not cover the tip of the probe with Teflon tape.

Another "Eh?". Why do you think that? Teflon is a dielectric, they make capacitors out of it. If it acted as an RF shield I think I'd have heard about it before now and I don't think the capacitors would work very well.

I have no idea how teflon capacitors are constructed. But the dielectric constant of teflon being really low, resistance is really high and leakage is low. Teflon wires are often used when trying to protect sensible signal from EMI.

Try to make a antenna with a piece of teflon wire for fun. It's not going to work really well

I think you're confusing insulation and shielding, it certainly sounds like like it.  RF shielding materials are all good conductors: copper screens, steel, mu metal. It's the copper screen in a coaxial cable that does the shielding, not the polyethylene or PTFE insulation that keeps the screen and the core apart. PTFE is probably one of the worst conductors in the world, with a bulk resistivity of 10¹⁸ Ω·cm.

Dielectric constant has little to do with RF shielding. Polyester, an insulating material with a dielectric constant of around 3.3 is used to make glassfibre RF transparent radomes. The dielectric constant of PTFE is abound 2.1, not much lower than polyester. Vacuum has a dielectric constant of 1, but RF has no difficulty at all passing through it or radio telescopes might be a bit of a problem.

For the record, PTFE film capacitors are made just the same way as other film capacitors: layer of metallization, layer of polymer, layer of metallization and so on. Same as polyester and all the other polly-put-the-kettle-on capacitor materials: polystyrene, polypropylene, polyethylene napthalate, polyphenylene sulphide and so on.

[Kosmic]

Teflon is a really good rf shield. If you want your probe to act a little bit like an antenna, I would not cover the tip of the probe with Teflon tape.

Another "Eh?". Why do you think that? Teflon is a dielectric, they make capacitors out of it. If it acted as an RF shield I think I'd have heard about it before now and I don't think the capacitors would work very well.

I have no idea how teflon capacitors are constructed. But the dielectric constant of teflon being really low, resistance is really high and leakage is low. Teflon wires are often used when trying to protect sensible signal from EMI.

Try to make a antenna with a piece of teflon wire for fun. It's not going to work really well

I think you're confusing insulation and shielding, it certainly sounds like like it.  RF shielding materials are all good conductors: copper screens, steel, mu metal. It's the copper screen in a coaxial cable that does the shielding, not the polyethylene or PTFE insulation that keeps the screen and the core apart. PTFE is probably one of the worst conductors in the world, with a bulk resistivity of 10¹⁸ Ω·cm.

Dielectric constant has little to do with RF shielding. Polyester, an insulating material with a dielectric constant of around 3.3 is used to make glassfibre RF transparent radomes. The dielectric constant of PTFE is abound 2.1, not much lower than polyester. Vacuum has a dielectric constant of 1, but RF has no difficulty at all passing through it or radio telescopes might be a bit of a problem.

For the record, PTFE film capacitors are made just the same way as other film capacitors: layer of metallization, layer of polymer, layer of metallization and so on. Same as polyester and all the other polly-put-the-kettle-on capacitor materials: polystyrene, polypropylene, polyethylene napthalate, polyphenylene sulphide and so on.

Yep you're right. I realized my mistake just before your post.

Excellent explanation as always 

[BU508A]

I did some researching and checked the ε_r and µ_r of PTFE.

If one wants to have a good electric shield, then it is recommended to use a good inductor conductor, because this will shorten the electric field lines. This is the principle of a Faraday cage.

If one wants to shield magnetic fields, one has to use materials with a very high µ_r, e.g. Mu-metal. The effect is similar to the Farady cage, the magnetic field lines will be shortened in the Mu-metal shield.

PTFE has an ε_r of around 2 which is not that high. Air, for example, has an ε_r of around 1.00059. Since PTFE is a very good insulator (around 1*10¹⁷ Ohm/cm) the shielding effect for electric fields should be very low.

Same goes for the magnetic field. PTFE has a µ_r of around 1 and therefore nearly no shielding effect to magnetic fields.

Please have a look at this diagram:



Source

Based on this, I cannot see, how PTFE should shield the magnetic field on my H-field probe.

You are right, PTFE is used for the insulation of cables in metrology. The main reason for this is its very high insulation resistance. This material reduces leakage currents very well. Can bee seen for example in the input circuits of electrometers. All the stand-offs are made of PTFE.

It could be that I am mistaken somehow. If so, please let me know where.     

Edit: corrected typo caused by tiredness...  thanks Neomys

[mnementh]

I have stayed away from Raspberry in droves for just that reason. If I wanted to run a version of *NIX even more castrated than android, on essentially a 10-year-old android Pwn without all the portability or a decent screen or usable touch interface... well, okay, I've never actually gotten past the "10-year-old android Pwn" part, so...

I just don't see the excitement; get a 10-year-old Dell PC at the Thrift for $10 and you have the same thing and another $30-50 in your pocket. 

mnem
*couch-tuber-time widda fam*

Eh? If you're implying that the OS on the Pi is a castrated Unix you're rather off the mark. The default is to run Raspbian (now inexplicable renamed Raspberry Pi OS) which is just the current version of Debian stable (buster at time of writing) built for ARM with hardware floating point. Nothing castrated about it, it's just vanilla Debian, the same as I've been running on my own servers for 15 years since I migrated off of Solaris.

There's also three flavours of Ubuntu, LibraELEC, OSMC, a handful of oddities and now a stable RiscOS, and as of a couple of weeks ago an experimental, official VMWare ESXi 7.0.0

Nothing castrated except that it's built for toy ARM processors, sure. 

mnem
 

[mnementh]

Teflon is a really good rf shield. If you want your probe to act a little bit like an antenna, I would not cover the tip of the probe with Teflon tape.

Another "Eh?". Why do you think that? Teflon is a dielectric, they make capacitors out of it. If it acted as an RF shield I think I'd have heard about it before now and I don't think the capacitors would work very well.

I have no idea how teflon capacitors are constructed. But the dielectric constant of teflon being really low, resistance is really high and leakage is low. Teflon wires are often used when trying to protect sensible signal from EMI.

Try to make a antenna with a piece of teflon wire for fun. It's not going to work really well

Edit: Ok, I think I'm mixing up good electrical properties and being resistant to electromagnetism. Technically Teflon should be transparent to RF.

Teflon insulated coax is one of the closest to "ideal" for wave propagation we've got so far; that's why it is preferred for cables used in our RC radios and FPV antennae. Makes calculating resonant length a few steps easier for math-defective old farts like me.

Our test for plastics safe to use on antennae is to stick a sample in the microwave for a couple 30-second exposures. If it doesn't get hot, good to go. Some black PLA fails spectacularly; lightning, fire, smell like a mad science popcorn experiment gone horribly, horribly wrong...

mnem
 

[0culus]

I have stayed away from Raspberry in droves for just that reason. If I wanted to run a version of *NIX even more castrated than android, on essentially a 10-year-old android Pwn without all the portability or a decent screen or usable touch interface... well, okay, I've never actually gotten past the "10-year-old android Pwn" part, so...

I just don't see the excitement; get a 10-year-old Dell PC at the Thrift for $10 and you have the same thing and another $30-50 in your pocket. 

mnem
*couch-tuber-time widda fam*

Eh? If you're implying that the OS on the Pi is a castrated Unix you're rather off the mark. The default is to run Raspbian (now inexplicable renamed Raspberry Pi OS) which is just the current version of Debian stable (buster at time of writing) built for ARM with hardware floating point. Nothing castrated about it, it's just vanilla Debian, the same as I've been running on my own servers for 15 years since I migrated off of Solaris.

There's also three flavours of Ubuntu, LibraELEC, OSMC, a handful of oddities and now a stable RiscOS, and as of a couple of weeks ago an experimental, official VMWare ESXi 7.0.0

Nothing castrated except that it's built for toy ARM processors, sure. 

mnem
 

Med, you better get in here with that big bag of popcorn. 



 

[0culus]

Teflon is a really good rf shield. If you want your probe to act a little bit like an antenna, I would not cover the tip of the probe with Teflon tape.

Another "Eh?". Why do you think that? Teflon is a dielectric, they make capacitors out of it. If it acted as an RF shield I think I'd have heard about it before now and I don't think the capacitors would work very well.

I have no idea how teflon capacitors are constructed. But the dielectric constant of teflon being really low, resistance is really high and leakage is low. Teflon wires are often used when trying to protect sensible signal from EMI.

Try to make a antenna with a piece of teflon wire for fun. It's not going to work really well

Edit: Ok, I think I'm mixing up good electrical properties and being resistant to electromagnetism. Technically Teflon should be transparent to RF.

Teflon insulated coax is one of the closest to "ideal" for wave propagation we've got so far; that's why it is preferred for cables used in our RC radios and FPV antennae. Makes calculating resonant length a few steps easier for math-defective old farts like me.

Our test for plastics safe to use on antennae is to stick a sample in the microwave for a couple 30-second exposures. If it doesn't get hot, good to go. Some black PLA fails spectacularly; lightning, fire, smell like a mad science popcorn experiment gone horribly, horribly wrong...

mnem
 

Don't lie, you microwaved the "other stuff" on purpose, didn't you? 

[mnementh]

Maybe... 

BTW, I'm not saying that all ARM processors are toys; just the ones they put in Raspberry.   

mnem
I LOVE ARM processors... fly 'em alla time. 

[mnementh]

Urrgh. Spent all day trying to find the parts for my 4070A from a CA warehouse... ANY CA warehouse... eventually gave up and paid the moosefucker tax; ordered it from DigiKey. 

Now facing exactly the same fucking headache, only it's the keyboard on my Lenovo Flex-3... which, joy of joys, uses the same keyboard as the Yoga (incorporated into the top cover) so it costs a fucking fortune, even from Shanghai. Or Shenzhen. Or Hong Kong... you get the drift.

mnem

Got really fucking lucky this morning. After hunting for hours last night and again over my morning cuppa, I decided to try my "last-ditch hail Mary" fix that every once in a while brings a keyboard back to life: cutting a mm or two off the end of the ribbon so when I plug it in, the contacts get a bite in fresh material. It's working now, for the time being at least; so I  was then able to clear that assache off my list, and concentrate on the day's main assache: mowing/bagging the back yard full of leaves so the clippings could go out for pickup tomorrow morning.

Assache and a half: Of course it starts raining about 1/4 of the way done. 

I survived it; wasn't sure I would, but I fortified m'self with acetaminophen & ibuprofen and plenty of coffee to power through. Then crashed & burned for the last 4 hours. 

   

And finally: When Amazon wants to, they can kick ass. Ordered this at 08:00 before I started shopping keyboards. Arrived at 18:00 while we were putting the recycles out. If you see a DYNAMEX van on the streets, give it wide berth. Motherfuckers must drive like it's the Cannonball Run. 

TEN FUCKING HOURS. I was expecting my parts today from DigiKey, being as it was sent Express yesterday; one of the benefits of paying the moosefucker tax is you get premium shipping built-in, so I NEEDED those heat-sinks ASAP!

It was horrible to have to order that coax crimping kit just to get same-day-shipping on all of it, but I took one for the team.     Total cost: US$33, including PayPal's little markup on the exchange rate.

In all honesty, I was surprised at what arrived; the jaws are sintered metal, but decently clean molding and meet well, with the cutout on one side for a proper flare strain-relief. It appears the dies are retained with hob screws, so should be able to adjust them to some extent with shims if ever needed. All in all, a lot better quality than I expected to get in a kit with the stripper and 5 ea BNC  (yay!) & PL-259 *blerk* for RG-58. I figure if I can make 3 usable patches out of that 22ft BNC cable I was using for testing my 4070A, I'll have gotten my US$25  worth.

UPDATE:



I've had a chance to use these, and they are definitely good value for money. They align pretty well for cheap stamped steel and sintered-metal dies, the crimp renders clean with the expected bugle-flare on the end, all well-formed as expected. 

That said, not best pleased with the ends that came in the kit; while the center hole is the correct diameter, the barb is too fat to fold the braid back over and crimp both sheathing and braid folded over the sheathing.

I was able to get a good crimp by skinning the blue Pliovic sheathing off to just the right length and pulling the braid up over the barb, then crimping with only the braid between the ferrule and the barb. Also, the center pin of those connectors are too brittle for crimping; I had to solder. The cable seems to work well up to the 30MHz max of the UTG-962E; no idea how badly I've affected the capacitance and reflected signal of that BNC at higher frequencies.

Looking on the intardnet, it appears this is exactly the way these are commonly used for HDTV and security cam installs... blearrghh.

https://youtu.be/ktQVwfo-s9w


I'm sure someone will be along to bust my chops for getting the Horror Fraught Special... I'm down widdat. As long as those BNCs keep the wiggly lines in that wire, all I care aboot.   

mnem
*toddles off to ded*

[Neomys Sapiens]

I did some researching and checked the ε_r and µ_r of PTFE.

If one wants to have a good electric shield, then it is recommended to use a good conductor, because this will shorten the electric field lines. This is the principle of a Faraday cage.

If one wants to shield magnetic fields, one has to use materials with a very high µ_r, e.g. Mu-metal. The effect is similar to the Farady cage, the magnetic field lines will be shortened in the Mu-metal shield.

PTFE has an ε_r of around 2 which is not that high. Air, for example, has an ε_r of around 1.00059. Since PTFE is a very good insulator (around 1*10¹⁷ Ohm/cm) the shielding effect for electric fields should be very low.

Same goes for the magnetic field. PTFE has a µ_r of around 1 and therefore nearly no shielding effect to magnetic fields.

Please have a look at this diagram:



Source

Based on this, I cannot see, how PTFE should shield the magnetic field on my H-field probe.

You are right, PTFE is used for the insulation of cables in metrology. The main reason for this is its very high insulation resistance. This material reduces leakage currents very well. Can bee seen for example in the input circuits of electrometers. All the stand-offs are made of PTFE.

It could be that I am mistaken somehow. If so, please let me know where.     

corrected that for you

[Neomys Sapiens]

Received today some tools from Wiha.

A side cutter, because the one I have already suffered a little bit from *cough* abusing *cough*.

And this nice Allen set (Inbus in German).

The side cutter is a Wiha Z 40 0 03 118 (27388) and the Allen set a Wiha 369H11 (36453).



I've also assembled an H-field probe. For this, I've used some semi-rigid cable which I've bought second hand last year at the UKW Tage in Weinheim. The white tape around it is some Teflon tape for the insulation. It is the same type of Teflon tape which can be found in a hardware store as a sealing tape for plumbing.



I did not calibrate it, because I just want to check if something is going on. Useful for some repairs.
This is a screenshot of the magnetic field of a toroidal choke of a Joule thief. Built one a while ago as a little torch. The oscillator runs at around 338kHz at 0.84V.

Ahem. WHAT HAVE YOU DONE NOW?
Signed: Der Ohrenbevollmächtigte der Werkmittel-Missbrauchskommision

[Neomys Sapiens]

since Christmas is approaching, here's something to get you into the mood.

https://youtu.be/dIeuBPDUzB0

Great find. At the last supper scene it had me laughing tears.

[BU508A]

Received today some tools from Wiha.

A side cutter, because the one I have already suffered a little bit from *cough* abusing *cough*.

Ahem. WHAT HAVE YOU DONE NOW?
Signed: Der Ohrenbevollmächtigte der Werkmittel-Missbrauchskommision

*mumbling*

Not sure. Just found a dent in the blades the other day. Must have cut something not suitable which I wasn't aware of...

*protect his ears with his hands*

Not pulling ears, please!

[capt bullshot]

Received today some tools from Wiha.

A side cutter, because the one I have already suffered a little bit from *cough* abusing *cough*.

Ahem. WHAT HAVE YOU DONE NOW?
Signed: Der Ohrenbevollmächtigte der Werkmittel-Missbrauchskommision

*marbling*

Not sure. Just found a dent in the blades the other day. Must have cut something not suitable which I wasn't aware of...

*protect his ears with his hands*

Not pulling ears, please!

Hmmm? A bit of abuse should look like this. It's just _slightly_ damaged and still usable 

[bd139]

I have stayed away from Raspberry in droves for just that reason. If I wanted to run a version of *NIX even more castrated than android, on essentially a 10-year-old android Pwn without all the portability or a decent screen or usable touch interface... well, okay, I've never actually gotten past the "10-year-old android Pwn" part, so...

I just don't see the excitement; get a 10-year-old Dell PC at the Thrift for $10 and you have the same thing and another $30-50 in your pocket. 

mnem
*couch-tuber-time widda fam*

Eh? If you're implying that the OS on the Pi is a castrated Unix you're rather off the mark. The default is to run Raspbian (now inexplicable renamed Raspberry Pi OS) which is just the current version of Debian stable (buster at time of writing) built for ARM with hardware floating point. Nothing castrated about it, it's just vanilla Debian, the same as I've been running on my own servers for 15 years since I migrated off of Solaris.

There's also three flavours of Ubuntu, LibraELEC, OSMC, a handful of oddities and now a stable RiscOS, and as of a couple of weeks ago an experimental, official VMWare ESXi 7.0.0

Ugh ESXi on one of them. I think that just gave me cancer.

[Saskia]

My rockpi does a splendid job of preventing Hubby to load trojans and virus onto my notebooks. It's good enough for web browsing.
And cheaper than scrubbing 26 trojans after his visit to a Russian gun website.

[bd139]

RockPi 4 is interesting. Has M.2 slot and is not touched by Broadcom's tentacles

[Zucca]

Go ahead, try it out and report. I trust you 100%.
Meanwhile I learn how to tame the FreeBSD animal.