Talk:Musa connector

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Plug / Socket[edit]

The picture is labelled incorrectly. The connector on the end of the length of cable is a Socket and the panel mounting connector is a Plug. I will try and take some better pictures. --jmb 12:07, 30 June 2006 (UTC)

Incorrect article title[edit]

The connector is properly (And popularly) known as a MUSA. It's a (reasonably obscure) acronym. I seem to remember it's something like Msomething Unit Steerable Antenna. It was orignally developed to go in the middle of an antenna, as it allowed joints to rotate (or something like that) but got taken up by the broadcasting industry. —Preceding unsigned comment added by 132.185.144.123 (talk) 15:46, August 29, 2007 (UTC)

From the OED --jmb 16:55, 29 August 2007 (UTC)
A radio aerial consisting of a number of rhombic elements in an end-fire array, giving a beam that can be varied in direction by varying the phase relations between the elements.
1937 H. T. FRIIS & C. B. FELDMAN in Bell Syst. Techn. Jrnl. 16 340 The word MUSA is coined from the initial letters of ‘multiple unit steerable antenna’. 1940 Bell Syst. Techn. Jrnl. 19 309 The principal parts of the two musa receivers occupy three rows of bays each about 25 feet long and 11 feet high. 1946 Nature 10 Aug. 190/1 Vertical angles were measured on transmissions from Rugby received at Holmdel with ‘Musa’ equipment. 1966 McGraw-Hill Encycl. Sci. & Technol. I. 447/2 The multiple unit steerable antenna, abbreviated MUSA,..has a directional pattern 1° wide at 18 Mc. 1992 RS Components: Electronic & Electr. Products July-Oct. 146/1 A range of MUSA style coaxial connectors widely used in the audio/video industry.
Well, there ya go. Don't know how to go about renaming the article, 'm afraid. --132.185.144.121 15:07, 2 September 2007 (UTC)
When an abbreviation is pronounced as a single word, as this one is, it's quite normal for it to be written in lower case with just the first letter capitalized. So there's nothing wrong with the article title - leave it alone. --Harumphy 16:11, 2 September 2007 (UTC)

Impedance[edit]

To substantiate my change of the impedance to 50ohm, work it out yourself! The inside measurement of the male screen is something like 6.8mm. The centre female contact is 3mm, the dialectric (air) has a constant of 1. The formula is (i think...)

138^elog(D/d)

D=inside screen diameter
d=centre contact diameter
e=dialectric constant

What is interesting is that some connector manufactures have redesigned the original to become acceptable to HDTV bandwidth requirements while still preserving the original 50ohm characteristic of the Musa barrel and U-link. I think they have done this by smoothing the transition of the differant impedances. It is the sudden changes in impedance that causes the reflections that cause poor performance and by properly marrying the 75 ohm BNC end to the 50 ohm Musa they meet the -15dB return loss quoted by SMPTE. I have put this on Talk as I won't be trying to quote referances and a lot of this is my opinion but i'm interested and would like anyone to properly prove, disprove or correct anything i have said (especially the formula as it might be wrong cos it was from memory...)(Virtualinsanity (talk) 15:51, 24 November 2007 (UTC))

The formula is 138*log10(D/d). You're right - it does work out close to 50 ohms. --Harumphy (talk) 17:44, 24 November 2007 (UTC)