Originally Posted by Riffmeister
You're only about 30 years off with that.
30 years? Explain. Note by CATV I mean the CATV company installations, not some independent master building antenna system. Perhaps that is the confusion.
The shielding issue is not a big deal. There are dual shield and quad shield RG59s. RG6 is simply better with higher frequencies than RG59.
Yes RG6 is better at HF. I though I made that point. And basic RG59 of that era was not double shielded. Remember that RF egress from CATV systems was a hot FCC issue in the early 1980s CATV construction explosion.
RG59 for TV and video has a characteristic impedance of 75 ohms. And many older TV studio installations used 50 ohm connectors, which was not a problem with baseband video.
As I said true
RG59 was 73 ohms. There were and are many RG59 size
cables made that are indeed 75 ohms but the classic stuff was 73. yes a 50ohm BNC connector is not an issue at 5mhz and 73ohms is close enough too at these frequencies.
RG59 is ubiquitous in analog TV installations. And I include Belden 8281in that because it is not RG6, it is a dual shield RG59. And also not as universally used as you suggest. For many installations a much less expensive and more flexible RG59 was used, such as 8241.
I know many industrial video systems as well as broadcast stations did use RG59 exclusively and at limited distances it was fine. But most network size plants and large production facilities always used 8281 or 9231. And it was RG6 sized, same rough diameter as 1694 although center conductor is a different gauge. I have seen far more 8281/9231 in the analog days than I ever saw RG59 as a program quality video cable. I used RG59 too but only for reference and monitoring feeds.Edited by Glimmie - 6/17/13 at 7:33pm