SP-1300 Combiner/Splitter vs Digital 2 way splitter

[shajoe44]

I was wondering what is the difference between the SP-1300 Combiner/Splitter vs those inexpensive splitters you can purchase at any electronics store. The frequency range on the inexpensive ones are 5-2500Mhz. Just curious in the signal lose and which one can be used to run 2 scanners off 1 antenna.

 

[Ubbe]

The difference are only the connectors. SP1300 has BNC and the cheap ones has F connectors.
Amazon.com: pigtail F bnc or if you can wait buy from China at 1/3 price and free shipping.

/Ubbe

 

[prcguy]

Inside TV type splitters and probably the SP1300 is actually a multi tapped transformer made with tiny ferrite beads and a couple of small value capacitors for matching. The TV type splitters are all manufactured for about $0.30 US and can retail anywhere from $1.99 to $30. These splitters do not perform the same as high quality commercial splitters made for general RF work, which might only have a fraction of a dB additional loss over the theoretical loss. A TV type splitter (and probably the SP1300) will have more loss and I've measured an additional 2dB or more at some frequencies over theoretical loss.

If you want to get a splitter with known very low insertion loss you can go with a commercial splitter for not much more $ than the questionable SP1300. Here are a few examples and you can sometimes find these used on Ebay in the $15-30 range.

Mini-Circuits
Mini-Circuits
Mini-Circuits

 

[shajoe44]

Thanks for the info. Basically I am looking for the most economically way of running 2 scanners off 1 antenna with the least amount of signal loss.

 

[cmdrwill]

Thanks for the info. Basically I am looking for the most economically way of running 2 scanners off 1 antenna with the least amount of signal loss.

Well, that just does not compute. Get a Mini Circuits one... and be done.

 

[Ubbe]

The expensive professional ones are manually calibrated for lab use when you need to know the exact values. The cheap chinese CATV stuff measures better than Stidsbergs multicouplers.

You'll always looking at 3dB loss when splitting a signal into two and then add the loss in the components, probably another 0.5dB for the cheap stuff and possible 0.2dB for the lab one. There' no way to change the way the law of physics works. You can use a good $30 low-noise preamp and overcome both the splitter loss and probably also increase your scanners sensitivity.

/Ubbe

 

[prcguy]

I've swept several satellite TV/satellite type splitters and have seen loss in a 2-way range from about 3.5dB to over 5dB depending on frequency and that's with matched 75 ohm inputs and outputs. Put a TV/satellite splitter in a 50 ohm system and it will be worse.

The expensive professional ones are manually calibrated for lab use when you need to know the exact values. The cheap chinese CATV stuff measures better than Stidsbergs multicouplers.

You'll always looking at 3dB loss when splitting a signal into two and then add the loss in the components, probably another 0.5dB for the cheap stuff and possible 0.2dB for the lab one. There' no way to change the way the law of physics works. You can use a good $30 low-noise preamp and overcome both the splitter loss and probably also increase your scanners sensitivity.

/Ubbe

 

[Ubbe]

I've swept several satellite TV/satellite type splitters and have seen loss in a 2-way range from about 3.5dB to over 5dB depending on frequency and that's with matched 75 ohm inputs and outputs. Put a TV/satellite splitter in a 50 ohm system and it will be worse.

0.18dB worse.

/Ubbe

 

[prcguy]

It might be .18dB theoretical loss with resistive loads on each port, but with random lengths of the wrong impedance coax it gets much worse at some frequencies.

0.18dB worse.

/Ubbe

 

[Ubbe]

It might be .18dB theoretical loss with resistive loads on each port, but with random lengths of the wrong impedance coax it gets much worse at some frequencies.

That's true. But as an antenna for scanner use only holds the designed impedance at some frequencies, besides perhaps a discone, and a scanners input impedance are all over the place, I wouldn't worry too much about mismatch problematics.

/Ubbe