RadioBanter - View Single Post

May 13th 05, 08:49 AM

wrote:

Folded dipoles were pretty common for TV. They are around 300 ohms. 4:1
baluns are common, so I figured 300/4 was how they got 75 ohms.

75 Ohm coax was used in early RADAR equipment for the video from the
receiver to the displays, as well as the internal video wiring.

It's hard to think of anything cheaper than the F connector, and for
mass market, you want cheap.

The "F": connector wasn't the first connector designed for 75 Ohm TV
coax. A lot of early MATV devices had the coax crimped directly to them
with a crimp ring used on the cheap "F" fittings. You had to cut the
ring off to remove an item for service. This was still common into the
early '70s. Early CATV systems were connected with "N" connectors that
had to be hand assembled and soldered to braided shield coax cable.
Drops to homes didn't use directional coupler type taps. They used a
"Stinger". You stripped the jacket off the cable and bolted a split
block over the .412 inch coax, then used a tool that cut a clean hole in
the shield. After the tool was backed off, you threaded the proper
"Stinger" into the hole, and connected the drop to the house. This
system was barely usable on 12 channel systems, and had so much RF
radiation that it had to be replaced when more channels were added to
prevent interference with other RF services.

--
Former professional electron wrangler.

Michael A. Terrell
Central Florida