Talk:Star quad cable

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Delivery of Split Phase Power[edit]

This article is about starquad cable which is intended for signal applications (low voltage and low current). Starquad has filler elements that strictly control the geometry. While the information in the split-phase section is a reasonable description of the advantages of using starquad for such an application , the references do not show any use starquad for power delivery. I'm inclined to delete the section.Constant314 (talk) 16:24, 19 March 2016 (UTC)[reply]

Rather than deleting this section, I have opted to edit it to make it a general discussion of other applications for star quad cable. The split phase example is technically feasible, but I cannot find any references for this specific application. The details were too specific to be relevant to the general discussion. It seemed more appropriate to provide a list and short overview of other uses for star quad configurations. For example, star quad cable is commonly used for audio speaker wire in order to reduce the magnetic fields emitted by the high currents that are used to drive speakers. Furthermore there is an example of an open-wire star quad radio transmission line cited in the transmission line page. I included this. I will be adding references for the star quad speaker wire, and I may include a mention of quad telephone wire, but the purpose of quad telephone wire is slightly different. Quad telephone wire uses a star-quad geometry to reduce the crosstalk between two pairs.--John Siau (talk) 13:56, 15 April 2016 (UTC)[reply]

Capacitance[edit]

The references do not support that the capacitance of starquad is double the capacitance of single pair. They only say that star quad in many cases has extra capacitance. References do not give any particular spec on capacitance. 200pF/ft is probably WP:OR. Reference does give frequency response curves for 100m with 600 ohm driver and 600 receiver. Constant314 (talk) 16:43, 19 March 2016 (UTC)[reply]

Please note that 600 Ohm audio transmission systems are rarely used today. Most modern systems use low impedance transmitters (usually 60 Ohms) and high-impedance receivers (usually 50 kOhms or higher). 600-Ohms systems are considered obsolete because of their limited ability to drive cable capacitance and because of their very poor common-mode rejection.--John Siau (talk) 14:04, 15 April 2016 (UTC)[reply]

Most microphones have an output impedance of about 150 Ohms. This number is probably most appropriate for examples involving microphones. 60-ohms should be used for examples of balanced line-level systems.--John Siau (talk) 15:44, 15 April 2016 (UTC)[reply]

I agree that the references do not support that the capacitance is double for star quad. It is generally higher, but it is not double.--John Siau (talk) 14:06, 15 April 2016 (UTC)[reply]

While you are at it, the introduction is probably too long. The guideline is not more than four paragraphs.Constant314 (talk) 15:06, 15 April 2016 (UTC)[reply]

Do you mean the introduction the the main article or the introduction to the second section?--John Siau (talk) 15:44, 15 April 2016 (UTC)[reply]

The intro to the main article. It is just a guideline. Nobody is going to delete the article because it has five paragraphs.

Also, I get 0.2 dB attenuation at 20 kHz for the 80m cable (12,000pF). I think you forgot that the capacitive impedance is reactive instead of real. Constant314 (talk) 15:49, 15 April 2016 (UTC)[reply]

The impedance of 12,000 pf at 20 kHz is 663 Ohms 20*log(663/(150+663)) is -1.77 dB. I corrected the 1.9 to read 1.8.--John Siau (talk) 16:30, 15 April 2016 (UTC)[reply]

The 663 ohms is reactive, hence imaginary

20*log(j663/(150 + j663)) = 20*log(1/(1 + j0.226)) = -20*log(1 + j0.226) = -20*log( sqrt { 1 + 0.226² }) = -20*log( sqrt {1.051})= -20*log( 1.0253) = 0.217 dB Constant314 (talk) 17:35, 15 April 2016 (UTC)[reply]

Yes thanks for catching the error! I will make edits.--John Siau (talk) 18:06, 15 April 2016 (UTC) Done--John Siau (talk) 18:13, 15 April 2016 (UTC)[reply]

Magnetic or electromagnetic?[edit]

There are several references to magnetic fields, etc. Should these be electromagnetic? Bubba73 ^{You talkin' to me?} 05:28, 9 April 2022 (UTC)[reply]

It doesn't really matter. If there is a changing magnetic field then there is a changing electric field. So, from the point of view of rejecting unwanted coupling, both magnetic and electromagnetic are valid. However, in this case, the magnetic part of the electromagnetic field is easier to visualize and describe, so you might want to stick with that. Constant314 (talk) 06:12, 9 April 2022 (UTC)[reply]

Thanks, I'm use to seeing "electromagnetic".

Also, in the article, sometimes "star quad" is hyphenated and sometimes it isn't. Which should it be? Bubba73 ^{You talkin' to me?} 06:35, 9 April 2022 (UTC)[reply]

I would go with star-quad since that the way it was with first edits. Constant314 (talk) 07:20, 9 April 2022 (UTC)[reply]

Broken links[edit]

Reference one (1), ten (10) are a broken links — Preceding unsigned comment added by 152.117.115.186 (talk • contribs)