you are of course going to have to help out there, as I fail my mind reading course at school
please educate us, I'm certain there must be any number of people wanting to know why its wrong.
Please also note that there are laws in europe that mean false and misleading information in advertising may lead to the company being prosecuted.
|I'm not defending the statements made by Eupen, I'm as much in the darkas the next person.
please educate us, I'm certain there must be any number of people wanting to know why its wrong.
Please also note that there are laws in europe that mean false and misleading information in advertising may lead to the company being prosecuted.
|I'm not defending the statements made by Eupen, I'm as much in the darkas the next person.
I am not deluded..saying that any number of people want to know.... is floobydust..zanash said:
e/m theory is boooooring..(I know)For an impedance discontinuity to reflect a signal within a transmission line, the wavelength of the signal must be in the same realm of the discontinuity in size. If prop velocity is in nanoseconds per inch for example, then a gig signal will encounter and reflect for entities that are in the inch realm.
If you examine their graphs, for example, you see not much attenuation until the frequency starts to get up to the 10 meg range. What discontinuity feature size is going to be required to begin reflecting signals at that frequency?
If you look at one of their data cables, you see 500 nH per meter, and 80 pf per meter...this translates into a Mu-Epsilon value of 4.49. This data points out the fact that they don't understand the relationships w/r to e/m field theory...they measured the inductance at either 100 hz or 120 hz, while the cable starts to do it's magic at 10 Mhz..4.49 is strictly the permittivity of the dielectric, the permeability of the ferrite has yet to show it's face at that low a frequency.
Note also they show the difference between their coax and standard on page 14....the graph has peaks at roughly 125, 250, and 375 Mhz..the ferrite isn't responsible for that...the measurement apparatus is at fault there..didn't anybody review that graph??
Also note that the wall outlets that are used everywhere on this planet, are themselves not of a characteristic impedance that is carried through the line wires.
I am confident their product does work in some capacity at attenuating rf style stuff, and see no reason not to try the stuff, it may find some very good nich applications, especially in enviro's full of or generating rfi.
They are not intentionally misleading others, they are doing a rather good job in their literature. Better than most, I must add.
If I were just starting out with motion control pwm servo amps in a complex multiaxis application, I would do well to consider their product. Having experience, I already know how to avoid far better, the issues their product addresses.
poobah said:Morning John... save your breath, they're not listening... a large cable maker with something to sell knows more than civic minded 3rd party scientists and engineers... heresay you know!
You never replied to my email from a few weeks back... or my spam blocker nailed you. Try again...
E-mail?
Can't find one. There has been a large increase in spam traffic of late, it may have been "absorbed" by Landrew.
Cheers, John
I bought some shielded Belden (branded Volex) power cords, in various gauges (three conductor). Cheap enough for me not to bother to DIY, and I think they are both foil and braid shielded. The thing is, they are moulded so I can't take them apart without destroying them. Anyone know how the shield is grounded, if at all? If I had any information that the shield is not connected to ground at all, I'd consider cutting off the moulded connectors and attaching my own.
I got a response from Volex: "Grounded at one end, the connector but not the plug end." Er, plug is what goes into the wall outlet... what the, they have it backwards! Maybe the contact made a mistake in his reply, but I'm not sure how to ask for confirmation without offending him
I guess I'll finish my X-ray set up soon and find out for myself...
I guess I'll finish my X-ray set up soon and find out for myself...
Nixie said:I got a response from Volex: "Grounded at one end, the connector but not the plug end." Er, plug is what goes into the wall outlet... what the, they have it backwards! Maybe the contact made a mistake in his reply, but I'm not sure how to ask for confirmation without offending him
I guess I'll finish my X-ray set up soon and find out for myself...
Oh, just get a cap meter and some aluminum foil..
Cheers, John
Hehe, I don't plan to be anywhere near it during operation. I do have an old dosimeter, but not thermoluminescent kind. But yes, it's a tube capable of 140 kV and 300 mA so I understand the potential for danger (not that house wiring could supply that much power).
I decided to get it mostly for cone-beam tomography, and possibly crystallography for another of my hobbies (chemistry).
By the way, any idea how the peak photon energy can be estimated from the accelerating potential? I understand that would depend on the tube geometry, but isn't there some approximation? The only figure I found is that 80 - 140 kVp gives average photons 60 kV from a standard medical tube... 80-140 is a very imprecise range, and I'm not sure the relationship between the two values is a linear one.
I decided to get it mostly for cone-beam tomography, and possibly crystallography for another of my hobbies (chemistry).
By the way, any idea how the peak photon energy can be estimated from the accelerating potential? I understand that would depend on the tube geometry, but isn't there some approximation? The only figure I found is that 80 - 140 kVp gives average photons 60 kV from a standard medical tube... 80-140 is a very imprecise range, and I'm not sure the relationship between the two values is a linear one.
Nixie said:
Can't help ya there. Peak photon energy of course, can't exceed the energy the electron has from acceleration, but I presume you mean peak intensity vs energy.. I don't know the envelope characteristic for Bremsstrahlung emission, I imagine K-shell emission would depend on target material.
Cheers, John
Yes, I was imprecise in my wording; a weighted (by intensity) average is what I really mean. The target in these rotating anode tubes is almost always tungsten, sometimes molybdenum, but save for some characteristic peaks I don't think it's the determining factor, since the peaks are fairly narrow.
ok, so if screening power cables, connect to the earth at the plug, but which end do i connect the screen in the mains lead from my pre amp to my power amp?
Or shouldnt i bother screening that one?
Or should i use a seperate lead from a socket to my power amp?
The power amp has no on/off switch.
Or shouldnt i bother screening that one?
Or should i use a seperate lead from a socket to my power amp?
The power amp has no on/off switch.
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