Showing posts with label connectors. Show all posts
Showing posts with label connectors. Show all posts

10/07/2011

VSIS-EU Cable TV Ground Loop Isolator Review

VSIS-EU Cable TV Ground Loop Isolator
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This story, like many others on this board, have striking similarities to each other.1. I buy an expensive new media center toy...
2. I experience buzzing from my speakers with the new device installed...
3. Call the cable company after tracing the buzzing sound to a poorly grounded CATV line (house is properly grounded too)...
4. Cable guy comes out and finds no problem even though he can hear the buzz as I plug in and unplug the coax...
5. Cable guy says TV has to be up pretty loud to hear buzzing, blames problem on TV...
6. I go into GTFO of my house mode... (important step)
7. Buy Viewsonics VSIS-EU CATV Ground Loop Isolator...
8. Plug in isolator...problem solved...no more buzz....
9. Post wonderful review for this product, immediately...

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9/23/2011

RCA VH48 Splitters (3-way) Review

RCA VH48 Splitters (3-way)
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In order to evaluate splitters, it is important to understand how they work. A splitter is not an amplifier. It takes a signal and divides it, so the sum of all the outputs must be less than 100% of the original signal strength, assuming even the slightest bit of signal loss. The goal is to have as little signal loss as possible.
Splitting a signal is like splitting a bowl of cake batter. If you split it in two, each new bowl would have 50% of the original, but some of it sticks to the original bowl, and some sticks to the mixing blades or spatulas. You might get 48% in each bowl, but if you were hoping for 76%, it's impossible. If you split one of the two new bowls, you will get two more with less than 25% each. A "78% batter loss" in one of the new bowls would be reasonable and is 88% of the maximum that is theoretically possible. (22 out of 25) Those who claim to be getting an 80% signal loss with splitters are in reality getting 80% of the theoretical maximum, and getting only a 20% loss, if the signal had been split twice. If they needed to add a new cable to use the splitter, it could also be part of the signal loss.
Some reviewers got a stronger signal from the port closest to the input. That means that internally, the signal is split once, half going to port one, and split again for the next two. A 7 db drop would be in the expected range for the second and third. My testing confirmed that the first port had a signal strength in the expected range for a two way split. The other two ports can do nothing more than divide what is left.
My setup consisted of an attic antenna with a two way Monster Cable splitter. It had very low signal loss. Replacing it meant that if the first port of the RCA splitter worked as described, the best I could expect from it was a signal level close to what I was already getting. I connected the first port to a cable that went to the family room, which is the farthest connection. I measured the signal before, and again after I changed splitters. I found that the signal strength was essentially the same as before for each TV channel. Any differences were within the margin of error caused by atmospheric conditions.
The signals remained within a percentage point in most cases, some higher than before. The signal to noise ratios were in about the same range as before, but there was a measurable difference in the AGC (Automatic Gain Control) levels. They were consistently about 1% higher (bad) but it's unlikely to be relevant for digital signals unless you start off near a 50% AGC level. You don't need to know what AGC is, only that the splitter does not cause a major problem for it.
The family room cable goes through a two way splitter before getting to the TV. That meant that the TV really got the same signal level as the other two outputs from the RCA splitter, just as it did with the previous splitter. The two way splitter also fed a media center PC, giving it the same signal level as the other outputs. Windows 7 Media Center allows users to measure signal strength, but does not give numbers. Each channel showed the same number of bars as before the change, as expected. In both cases, I got the maximum number of bars, all green.
Since the circuitry to split the other two ports is identical to that used with the first port, and since the connectors are the same on all ports, it's reasonable to assume that the quality is equally good for all ports. I don't have hard measurements from the other two ports but my bedroom TV now works the same with half the signal, and my office PC now has a strong connection.
In my case, nothing but the splitter changed between the antenna and the family room for these tests. If you have a cable going to your TV and you add a new splitter, you end up with three cables instead of one, and four more connectors. Unless you know how much signal loss there is from the cables and connectors, you can't tell how much is from the splitter. My signal loss dropped significantly when I stopped using the RG-59 coax that came with the house, and ran more direct RG-6 quad shielded cable throughout the house, both inside the walls and out. I used Steren Permaseal-II connectors, which minimized signal loss.
If you get this splitter and it does not perform to your satisfaction, getting a better one may not be the answer. Make sure that your cables are all of top quality and have top quality connectors. Don't use cables with twist-on connectors. Make sure that all your connections are tightened with a wrench. Make sure that you don't have splitters anywhere with more outputs than you need. And if that still does not work, look into getting a signal booster.
Some reviewers have criticized this splitter for its frequency range. TV frequencies go from 54 MHz to 890 MHz. This splitter goes from 5 to 1000 MHz and covers the entire spectrum. There are many uses for splitters, but if you are not splitting a TV signal, this may not be what you need. Cables that go into your set top
box might not be carrying TV signals at all but carrying digital data that the set top box can decode. Some data may be in higher frequencies. If you have cable TV, check with your provider. They might even give you splitters and cables for free rather than risking signal leakage.
Overall, this splitter worked almost as well as a much more expensive one, and the "almost" part was so small that it did not make a difference. If you need a three way splitter for TV frequency signals, I'd recommend this one.

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9/20/2011

Mini Null Modem DB9 Male / DB9 Male, Adaptor Review

Mini Null Modem DB9 Male / DB9 Male, Adaptor
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I needed a small form factor Null Modem and a Gender Changer, this item promised to be be both in one package. Upon installation in my setup (GPS to position enabled radio) the GPS unit was not communicating with the radio. Checking the GPS, I found it to be functioning fine, checking the cables, I found them to be working. I then checked the individual pin-outs on this device and found all pins to be a straight through. 1->1, 2->2, 3->3, etc. This is NOT a null modem but it makes a fine gender changer if you happen to need one. If you need a Null Modem, buy something else.

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8/29/2011

Cables To Go 10480 DB9 F/F Null Modem Cable (1 Feet, Beige) Review

Cables To Go 10480 DB9 F/F Null Modem Cable (1 Feet, Beige)
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Needed a short null modem cable to use in conjunction with USB to serial cable. Works quite well good speeds and clean data can't ask for much more from a cable.

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8/21/2011

TII 212 Broadband Cable TV Lightning Surge Protector Review

TII 212 Broadband Cable TV Lightning Surge Protector
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I live in the lightning belt of Central Florida and the lightning has done terrible damage to electronics in the past. It is important to ground and surge-protect all lines that enter a home (Power, Cable or Satellite, Telephone...). I considered installing a surge protector on the main cable line coming in, but all the units I found were the kind that plug into an electrical outlet. Then I found this item on Amazon. It arrived in a day (thank you prime) and the install took under 5 minutes (I posted a picture of what it looks like). It is compatible and completely transparent to broadband cable internet and digital cable with no service issues whatsoever. And with 1500 surges and is self-resetting, this should last a while. Overall, I am very happy with this product.

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8/09/2011

Mini Null Modem DB9 Female / DB9 Female, Adaptor Review

Mini Null Modem DB9 Female / DB9 Female, Adaptor
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Product would have been fine if i needed a gender changer, but I ordered a null modem adapter and the tape around the connectors said it was but the pins were all straight connections. I bought this so I wouldn't have to dig out an old 20' null modem cable but had to resort to that all the same since this didn't give me the cross talk like i needed.

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