Silver RCA Cable-share your experience, opinions here!

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Waly

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No, it's probably a correct and money saving decision. Last time I've checked a Keithley picoammeter schematic, the protection was between the hot and the guard. Since the guard is driven to minimize the leakage, the diode sees essentially zero volts during normal operation. So the 1N914 leakage is also zero, a picoampere diode as BAV40 (5pA@5V) would not do any better. Actually I've never seen a diode with 1e-17 leakage (62 electrons per second), they may exist for some nuclear detector applications?
 
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mmerrill99

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Joined 2014
jneutron said:
BTW, several encoder vendors have specific shielding requirements for their long encoder runs. It is a double shield technique, coaxial shields.

But only one of them is connected to ground at both ends. One is connected only at the receiver. The inner shield does not connect at the encoder, the outer shield is connected at both.

The theory: The inner shield is an electrostatic shield. If this were the only shield, the different potential between grounds would show up as common mode noise in the differential pair signal.

The outer shield connects to ground at both ends. Any ground current will travel the shield, and the shield will try to limit the common mode voltage excursion. The beauty of this system is that there is no magnetic field within the outer shield as it is cylindrical. So it prevents any coupling to the inner signal wires, and further reduces the voltage potential end to end that the electrostatic shield protects against.

The down side to this is...I typically have 4 to 6 of them running 100 feet from rack to equipment. While each cable protects it's internal signals from shield currents, nothing can protect the other cables from the external field of the shield currents. So the design from the vendor falls apart once multiple devices are used.

jn
Click to expand...

This seems to be an application of what you mention - a USB cable with 3 coax shields which can be connected in various ways
Lush^2 - Share your configuration experiences - General Forum - Computer Audiophile

Is this a suitable mitigation of Shield Current Induced Noise - What's your take on it?
Jim Brown's paper is an interesting read on this Shield Current Induced Noise - Causes and Solutions

BTW, do you have examples of this dual shielded coax?
 
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scott wurcer

scott wurcer

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Joined 2004
jneutron

jneutron

Member
Joined 2004
mmerrill99 said:
This seems to be an application of what you mention - a USB cable with 3 coax shields which can be connected in various ways
Lush^2 - Share your configuration experiences - General Forum - Computer Audiophile

Is this a suitable mitigation of Shield Current Induced Noise - What's your take on it?
Jim Brown's paper is an interesting read on this Shield Current Induced Noise - Causes and Solutions

BTW, do you have examples of this dual shielded coax?
Click to expand...
The paper is reasonable. One factor in cable design he missed is how cylindrical the braid is. The fillers are sometimes used (not sure if intentional or not) to make the braid fully cylindrical. If not done, the braid will couple to the wires.
One place I would be concerned about is his test setup, he forms a loop by connecting the shield drive to scope channel B.
Other than those small points which probably have little impact on results and conclusions, a well done paper.
I don't have any of the cables, cables are turnkey for all the installs, the techs would cut the rack end to length, the cutoffs always end in scrap. We had lots of scrap as we'd pull ten or so like type cables through tray and conduits so didn't have the luxury of pull to length.
Since we have multiple cables in tray, the concept of triax is of no help to us due to one cable shield being next to another.
Jn
 
W

Waly

Banned
Joined 2011
W

Waly

Banned
Joined 2011
scott wurcer said:
I use an electrometer to measure log conformance to as low a Vd as possible. Also watch out for those glass diodes and photo current.
Click to expand...


I used FJH1100 from Fairchild (now Onsemi) that have 3pA@5V Max. and they were under 20fA@1V but those are expensive, about 10 quid a pop.


BAV45 are also good, if you can sort them, but the good samples in metal can are today as rare as hen's teeth.
 
Rick Miller

Rick Miller

Member
Joined 2008
Cap burn in

Here is a link to a YouTube video showing how Audioquest burns in capacitors that are used in their power line conditioners. Someone had brought up that on the Audioquest web site they talk about using a method that is from NASA for burning in their caps. This shows how it is done.

Start at 6:15 into the video.

YouTube

Do you think that they would invest this kind of time and money if it did not make the caps sound better?
 
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