[mythtv-users] HDHomerun signal strength required

[Brian Wood]

backuppc at sundquist.imapmail.org wrote:

> 
> Right now I have a single pcHDTV 5500 card which works OK except when
> the weather is bad and the weather is often bad.  I want to see if it
> truly is a problem with poor reception with this card as the wiki
> suggests.  Plus I need more than one tuner, so the HDHR is on the way.
> 
> But now I have three RF jacks to split into (one 5500 and two HDHR).
> The splitters seem to come in 1:2 and 1:4 varieties.  Should I just use
> a 1:4 splitter and leave one empty?  Would this cause "reflection"
> problems as noted in the above link?  Would I need to put a terminating
> resistor on this?

Yes, you should terminate any unused outputs with a 75-ohm terminator.

In fact you can get 3-way splitters, though they can be hard to find. 
The loss is about 5 db. per tap, as opposed to 7.5 db. for the 4-way units.

> 
> Another related question:  My daughter sometimes may want to play an old
> VHS tape or two we have laying around.  I am not converting these all to
> DVDs.   Our VHS player outputs to coax on NTSC channel 3.  I could have
> the pcHDTV card (which does NTSC as well as ATSC) pick that up (right?).

The pcHDTV card is a digital and an analog tuner, but the analog tuner 
is a simple frame grabber, thus you will have to encode using your CPU. 
Myth will record your VHS tape, though it's a bit of overkill. Myth only 
supports RTJpeg or MPEG4 with a frame grabber card, the former is 
suggested unless you have a fast CPU.

> Could I plug that into a 1:4 splitter, effectively making it a 2:3
> splitter?  Another way to pose that question is "even though four of the
> five F-plugs say `out' (see
> http://rsk.imageg.net/graphics/product_images/pRS1C-2265543w345.jpg) are
> all five in fact wired in parallel?"

I would not do that. Although a hybrid splitter will act as a combiner 
(backwards) you might (actually almost certainly will) wind up 
transmitting the channel 3 signal out your antenna, causing outfits like 
the FCC to take an interest in your activity.

> 
> I actually have a merger up in the attic of two directional UHF
> antennas, so I am probably looking at all kinds of efficiency losses.
> Should I consider a signal amplifer after the merge?  My DTV signal
> strength could be better.

Combining two or more antennas can work, and is often done, but you have 
to be sure you have the phasing correct, and this will be affected by 
things like cable length (inches make a difference).

> 
> Sorry for asking what are basically not true myth-related questions, but
> since this thread was already started...

They are Myth-related in that a lot of Myth users face similar issues.

beww