Tips, tricks, hints and more on mic and headphone cables, and staying organized
Feb 1, 2009 12:00 PM, By Chriss Scherer
Watch out for snakes
Robin Cross, chief engineer at KCUR-FM Kansas City, needed a snake for the station's remote kit. The snake had specific needs for types of connection: A commercially available snake would work, but required a greater expense than the station wanted. Also, the KCUR remote kit is just that � a kit. There is no remote truck, so the snake needed to be lightweight. Cross improvised and created a solution.
Cross' custom snake
He used Belden 1804 for the four mic cables. The 1804 has four wires � two blue and two white � within an overall braid, which improves the CMRR of the cable. The outside diameter of 1804 is 0.15�.
He also bought four headphone extension cables (�" F to �" M). He bought two different sizes of woven expandable sleeving from Grainger in ?" (PN-1UXW8) and �" (PN- 1UXY1) sizes. Other sizes are available. The reels came in 50' lengths. The smaller size was used to separate a mic and headphone cable. The larger size was used for the overall snake. In working with the sleeving it became apparent that he needed to melt the entire sleeve and then work the wires that were to go inside through the side of the weave. He color coded each mic and headphone cable in pairs with Scotch colored electrical tape and then covered that with clear heat shrink.
This tip came to us some time ago, but was buried in the pile. David R. Wilson, engineer for the Cromwell Group in Nashville, TN, offered these ideas.
When you have two full-timers and two part-timers to cover 22 stations, it isn't easy to keep up, much less make progress. I have been using a twiki (www.twiki.org) to document what I have been doing, all expenses (eventually), and make a list of hot links to manuals on the Net. I have several things that I attempt to do on a schedule. Due to many surprises that schedule is not always followed to the letter.
I have also had some interesting challenges. One of the stations for which I am the chief engineer has a history of getting knocked off the air because of equipment failure or abuse by nature. Besides doing a lot of troubleshooting, grounding and minor changes to the equipment, I put in a programmable logic controller (PLC) to control the site several months ago. Things have been much quieter since. When the main transmitter goes down something will usually be on the air in six seconds.
The backup will come up when it is ready. If the main does come back up the PLC will shut off the backup transmitter and put things back to the default status. A power failure will add an additional 8 seconds to the recovery time. If both transmitters are blown up and the PLC is down as a last ditch effort the IBOC transmitter will come up in analog+IBOC by default.
Otherwise, lots of overtime seems to work.
Last month, John Landry offered some tips on finding a cable break by using an inductive tester. He also described a method to use a power amplifier to increase the test signal in noisy environments. In the printed version of the story, he mentioned a situation where he used an available speaker amplifier. This might have caused some confusion to suggest that the speaker was attached to the far end of the cable. The speaker amplifier was used just like the Crown power amplifier that was described. No speaker was attached, just the output of the amplifier to feed the line being tested.
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