Talk:Installing a TV aerial

From DIYWiki
Jump to navigation Jump to search


why would one delete this:


- Nearly all TV aerials are described by the manufacturer as 75 ohm aerials, yet nearly all are really designed as 300 ohm aerials, with construction details reducing this to some degree, but not to 75 ohm. Connecting a 300 ohm aerial to 75? cable causes loss of gain, tendency to reflections, and some degree of degradation of signal quality. - - Better aerials have a small balun inside that transforms the 300 ohm signal to a genuine 75 ohm feed. All CAI approved aerials have this. NT 23:55, 4 March 2009 (GMT)

It did not really seem that relevant since the article already strongly suggests CAI aerials (which will all have a balun when required (i.e. allowing for CAI approved Log periodic aerials which are naturally balanced and have a 75 ohm impedance)). It was also somewhat inaccurate as currently described (see Bill's comments about the effects of parasitic elements on characteristic impedance).

Perhaps a simpler statement would be in order? --John Rumm 00:24, 5 March 2009 (GMT)

Note I have added an aerial quality assessment "bullet list" to the CAI section mentioning baluns now. I also took out the gain categories bit since this is duplicated in the gain section anyway. --John Rumm 01:05, 5 March 2009 (GMT)

A recommendation to use CAI approved aerials doesn't mean everyone will use them. For those that dont, a balun is a key indicator of quality. Perhaps what I wrote was unnecessarily long, not sure, was trying to explain why a balun is a basic for decent performance. NT 10:46, 5 March 2009 (GMT)

Yup agreed... I think the message to get across is that its worth having and an indication of a better aerial. rather than give a technical explanation of what it does or how it works.

Hopefully the bit I put in the CAI section covers this:

"If in doubt when choosing an aerial, look for one which:

   * Has a strong construction if you're using it outdoors
   * Has a reflector made from several elements and not a simple perforated reflector plate stamped out of a flat sheet of metal.
   * Includes a balun to ensure proper matching to the aerial downlead (note, "log periodic" aerials do not require baluns). "

--John Rumm 12:14, 5 March 2009 (GMT)

Sounds like a good solution NT 22:36, 6 March 2009 (GMT)