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Michael Black[_2_] Michael Black[_2_] is offline
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Default 75 ohm Termination Question

On Thu, 13 Feb 2014, Jeff Liebermann wrote:

On Thu, 13 Feb 2014 17:41:28 -0800, Bennett
wrote:

On 2/13/2014 5:17 PM, Jeff Liebermann wrote:
On Thu, 13 Feb 2014 10:40:26 -0800, Bennett
wrote:

A friend replaced her Comcast TV box with an over-the-air antenna but
continues to use Comcast Internet service. This leaves her
Comcast-supplied splitter with an unterminated socket - does it matter?

Yes, it matters.

Should I bother to terminate it?

Yes, you should terminate it.

(A barrel connector isn't a good replacement for the splitter as the
splitter provides a grounding point.)

Sorta. Apparently she has a 2 way splitter installed with one port
left unterminated. A barrel connector is a very good replacement.
However, you're correct that you'll need to do something about the
grounding point. If this is indoors, just remove the grounding wire,
wrap it around the barrel connector, and hold it in place with a small
hose clamp. For outdoors, use a proper grounding clamp:
http://www.solidsignal.com/pview.asp?p=pvgb1&d=perfect-vision-pvgb1-single-grounding-blocks-%28pvgb1%29
https://www.google.com/search?tbm=isch&q=cable+tv+grounding+block
For outdoors, also don't forget to recreate the coax drip loop so that
water doesn't run into the connector block, or into the house.
http://activerain.com/blogsview/3168531/drip-loop-really-do-you-need-it-wenatchee-and-leavenworth-home-inspection
http://images.meredith.com/diy/images/2009/03/p_SCW_240_02.jpg


Thanks for all your replies. It's an indoor splitter. Since I had a 68
ohm resistor and appropriate connector (but no hose clamp), I just built
a terminator. Factory-builts are cheap - if you want 10, 25 or 100 but
I only needed one.


Not good enough. If you just crammed a 68 ohm resistor into the
F-connector jack, you probably have a fairly good approximation of an
antenna. It's going to radiate junk, and pickup more junk (ingres).
If you insist on doing it like that, wrap the resistor with some
insulating tape, and then cover it with aluminum foil.

One time I was looking into switches that couldn't be accidentally
toggled, and I thought of type F connectors.

I'm sure I took a bit of wire for the center conductor, then a bit of thin
copper sheet. PUt the wire into the centre of the copper sheet, soldered
it, then soldered the copper sheet to the outer part of the connector.
So switching was by screwing in the connector or unscrewing it.

I'm blank about soldering the copper sheet to the outer part of the
conenctor though, but I can picture the finished connector.


Yeah, you're right that nobody sells them in small quantities. The
best I can do on eBay is 10 pcs for $3.85 including shipping.
http://www.ebay.com/itm/261230167868

That's why I tend to keep junk. Terminators may seem like the most
mundane thing found in a pile of junk on the sidewalk, but if you need
one, you actually save money and effort, while the 60gig iPod that I found
somewhere else needs a battery in order to be useful.

Michael