Coax Splitting

[RemoreKnight]

Hello,

        I need to make a coax cable run of ~150'.  At the termination it needs to be split 3 ways.  Is it better to split it at the beginning and run 3 cables or run 1 cable and split it at the end?  

        Any other advice on splitting coax would be appreciated!

Thanks!

-Jason

[Greg Oman]

Run then split.  With that length of run you will have line losses to consider-- depending on what signal you're sending.  For example, if this were from an antenna for OTA, you may or may not be dealing with a weak signal to start with, and the line loss of the coax will vary by the frequency.  So IF you have to amplify, you've got one line to do not 3.

The logic behind this is that line losses are a function of cable length, then you have splitting losses, a 1-2 takes what signal you have and cuts it in half, then you have (presumably) a shorter cable run with it's correspondingly smaller line loss, but it all adds up.

Greg O.

[joetwc727]

the type of cable you use will make the difference

RG-6 cable loses 1.60 db per 100 feet @ 55MHz
                           5.65 db per 100 feet @750Mhz

RG-11 cable losses .96 db per 100 feet @ 55MHz
                             3.77 db per 100 feet @ 750MHz

your best bet is to run one cable and split it at the end to save money on cable, since the lose would be the same either way.

[Greg Oman]

Good point Joe.  This may help:

Ch 2-6  VHF   54-88Mhz
Ch 7-13 VHF  174-216Mhz
Ch 14-69 UHF 470-806Mhz

Each channel has 6Mhz of bandwidth, fo ch 14 operates in the 470-476 range, ch 15 476-482, etc.

DBS starts at 900Mhz and goes up to 2.2Ghz, so depending on your usage, keep that in mind.  RG6 has 2 common flavors, 18gauge would have lower line losses per 100' than 22gauge.

Greg O.