Splitter Question

[GKolo]

You know the splitters that the cable company uses or you can buy at the Mart stores with the F connectors where you can make 1 line into 2 or 3 or 4....
On the front of the splitter it says - 3.5 DB under each output....So it knocks down the signal.......

Well removing the back of the splitter reveals a small circuit board with all kinds of stuff on it.
If i take the board out and put a piece of copper wire between the center contacts will it work as a decent splitter and not knock down signal for a scanner to much ?

 

[n5ims]

You know the splitters that the cable company uses or you can buy at the Mart stores with the F connectors where you can make 1 line into 2 or 3 or 4....
On the front of the splitter it says - 3.5 DB under each output....So it knocks down the signal.......

Well removing the back of the splitter reveals a small circuit board with all kinds of stuff on it.
If i take the board out and put a piece of copper wire between the center contacts will it work as a decent splitter and not knock down signal for a scanner to much ?

No, that won't work as you would like it to. The splitter does two important things. First (as is obvious) it to split the signal up. Second is to prevent signals from the one connected device from interfering with the others. A scanner uses radio frequencies to mix together to allow it to tune in the one you want. If the signal from one scanner reaches another one you may get signals that aren't really where you're tuned to.

The loss isn't really from that circuitry, but from splitting the signal to feed the multiple devices. Say you have 4 units of signal from your antenna (the units don't really matter since this is simply an exercise to help you understand what's going on). If you connect it directly to a single scanner it will get the full 4 units. If you hook up two scanners, you'll divide that signal to supply each scanner with the signal so both will end up with 2 units of signal. If you hook up four scanners each will end up with one unit of signal. It's not complicated, just simple math. That 3 dB listed on the splitters isn't magic either since 3 dB of loss translates to half of the signal. Splitters aren't actually this simple, but in general, this is pretty much how things are.

 

[GKolo]

Ok it wont work.....But i did have fun taking it apart ...LOL

Even if all your doing is splitting the incomming feed from the antenna to 2 different radios with nothing being transmitted ?

 

[RonnieUSA]

OK, it wont work.....But i did have fun taking it apart ...LOL

Even if all your doing is splitting the incoming feed from the antenna to 2 different radios with nothing being transmitted ?

I just installed one this week on a Homebrewed Off-Center Fed Dipole, that I made following the wiki.
Homebrewed Off-Center Fed Dipole - The RadioReference Wiki

I saw no lose of signal, I may be one of the lucky few though.
But it works, and I'm a happy as a lark.

 

[GKolo]

I may walk on the wild side tomorrow and hook it up.

 

[popnokick]

Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 6_1_2 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/6.0 Mobile/10B146 Safari/8536.25)

RonnieUSA- glad you chimed in here. I also use a cheap CATV splitter with my OCFD and have not noticed the tremendous, undesirable halving of the total signal to each scanner. Amazing.
I think that most users have plenty of signal coming in from the usual stuff people want to hear on scanners. In fact, many people have too much signal causing a receiver overload and knocking it down a bit with a cheap splitter may actually help with FM and paging transmitter overload, and close proximity to transmitter towers.
And what's the real question here? Cost? These splitters run about $2-$10. Buy a couple. If one doesn't work throw it out and try the other.
Now... If you're trying for the distant, tiniest 800 mHz signal that is two counties away and you're not on a mountaintop.., DON'T use a splitter! Still need to split the signal, you say? Start looking at Stridsberg, Electroline, etc. Oh yeah... A few more bucks than a cheap splitter. But try the cheap first. If no like, toss it.

 

[K4APR]

I'm surprised no one has touched on the fact that these "TV Splitters" are 75 ohm and the scanner input impedance is 50 ohm. You can't simply use the splitter as-built.

 

[GKolo]

Update:
I took a cable splitter and removed the back of it, cleaned all the guts out of it and soldered a solid copper wire to the center connector.
So now 1 antenna is feeding 2 scanners. I am quite happy with it !
i did some testing and picked up 5 of the 7 NWS channels with the antenna straight into the scanner, with the splitter i still get 5 of 7 NWS stations.
Say what you want but it works for me.

 

[737mech]

Noise between scanners

Update:
I took a cable splitter and removed the back of it, cleaned all the guts out of it and soldered a solid copper wire to the center connector.
So now 1 antenna is feeding 2 scanners. I am quite happy with it !
i did some testing and picked up 5 of the 7 NWS channels with the antenna straight into the scanner, with the splitter i still get 5 of 7 NWS stations.
Say what you want but it works for me.

Ok so now that some time has passed for you to test this how's it working now? NWS is very strong in my area so a paper clip would do ok for an antenna, in fact I filter it out with a par vhfsym162.
I currently run one antenna into a 4 way splitter (with the guts) and occasionally I get problems with one scanner making noise on the other. Even though my splitter has port isolation the following problem happens. My BCT15x can stop on a trunked talkgroup, nice strong signal, my bc125at will fuzz on a uhf airband freq, so I have to lock it out. I have read this is because the occilators interfere with each other because there's a path between them via the splitter. It's strange because if I only scan airbands on both no problems, if I switch on a trunked system I get problems. I guess that's the trade off with one antenna to several scanners?