[mythtv-users] Coax splitters - how painful are they?

Brian Wood beww at beww.org
Thu Sep 27 15:11:42 UTC 2007

Dean Wilson wrote:
> On 9/25/07, Jay R. Ashworth <jra at baylink.com> wrote:
>> On Tue, Sep 25, 2007 at 09:56:04AM -0400, Tom Dexter wrote:
>>> For OTA would he possibly be better off using a mast mounted amp
>>> rather than a powered splitter?  That's what I'm doing.
>> If you're OTA, you're *always* better putting the amp up the pole, yes.
> When I first put up my antenna, I didn't realize this, and put the amp
> in the basement just prior to my myth box.  My setup (and question)
> follows:
> I'm 50-60 miles from the stations in Kansas City, where I pull in all
> my channels.  I have an outdoor antenna mounted ~25 feet above my
> house.  I then run the cable across the house, through the main floor
> to the basement, so it's a fairly long (75' ?) run, but I did buy good
> coax (I think Belden 1694A:
> http://bluejeanscable.com/pages/technicaldocs/1694tech.htm) that
> supposedly has low signal loss.  My signal strength is decent, but I
> get frequent "blockiness" on the HD channels which I assume is a weak
> signal/signal loss.
> I've read on this group that I may be better off without an amp, which
> I'll try, but at my distance, and with the cable run I have, I doubt
> it.  That said, I'd rather not pull down my antenna to replace it with
> a larger one, or to put the amp at the antenna, since getting the
> antenna up in the first place was pretty tricky.  However, I could
> easily place the amp in my attic, which would put it ~30' from the
> antenna.  My question is: assuming I determine that an amp is needed,
> how much would it help for me to put the amp in the attic?  I'm
> worried that after I cut the line in the attic, if I find that it
> doesn't help enough, I've now severed the line and weakened the signal
> for whatever next method I try...

First, I wouldn't worry about cutting the line. If you need to splice it
together again, as long as you use the proper connectors and crimping
technique you should not have any measurable loss. One main reason
people try and avoid splices is that they reduce the weather-tight
integrity of the line, but if you are in your attic that shouldn't be a

Next, I doubt that moving your amp closer to your antenna will make any
noticeable difference, unless you are eliminating 100' or more of coax.
It's true that in general putting a preamp as close to the antenna as
possible is good engineering, but the real answer would depend on what
levels you are getting out of your antenna. You have to look at the
entire system (antenna levels, coax losses, amplifier gain, splitter
losses etc.) and truly "engineer" the system. Unfortunately most
consumers do not have either the instrumentation or the expertise to
perform such calculations, nor is it really necessary in most cases.

It also depends on what sort of amplifier you are using, an antenna
pre-amp or a distribution amplifier. The former is intended to boost
weak signals from an antenna and the latter to make up for
cable/splitting losses.


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