[mythtv-users] HDHomeRun(s)

Greg Oliver oliver.greg at gmail.com
Thu Jan 14 18:29:12 UTC 2010


On Thu, Jan 14, 2010 at 12:23 PM, Ben Kamen <bkamen at benjammin.net> wrote:
> On 1/14/2010 12:18 PM, Greg Oliver wrote:
>>
>> On Thu, Jan 14, 2010 at 12:13 PM, Ben Kamen<bkamen at benjammin.net>  wrote:
>>>
>>> On 1/14/2010 12:02 PM, David Brodbeck wrote:
>>>>
>>>> On Thu, January 14, 2010 7:14 am, Greg Oliver wrote:
>>>>>
>>>>> I am just wondering how the same cable connected to a TV produced
>>>>> different results when connected to the hdhomerun..  I can only assume
>>>>> the TV has pretty good gain or something???
>>>>
>>>> Yeah, it's possible the TV's tuner is more sensitive.
>>>
>>> Ehhh, TV tuners are of wide quality. When it comes to your TV, they're
>>> just
>>> as interested in saving $0.02.
>>>
>>> Of course, you could test this if you have a sig meter somehow on both
>>> inputs for a given channel.
>>>
>>> Keep in mind, when you split the signal, you lose about 3.5dB per split.
>>
>>> From the antenna, there is one 4x1 splitter.
>
> So each leg has an instant 7dB loss there. ( in losses 3dB=1/2 power,
> 6db=1/4power )
>
> Is this an active or passive splitter? If it's passive, this would be a
> great place to put an active
> splitter, then your 4way would realize no loss and possibly some gain to
> boost the signal down the line.
>
>>> So if you have -10dBmV coming in and put it through a 2 way splitter, you
>>> now have -13.5dBmV coming out
>>> the 2 ports.
>>>
>>> The 3 output splitter on my house for CATV has
>>> Input --->  3.5dB loss
>>>       |->  7dB loss
>>>       \->  7dB loss
>>> And so on. So your test environment could affect your reception quality
>>> as
>>> well.
>
> So there's another split down at the bottom? Another 3.5dB?
>
>> I live in Dallas, TX, and can pick up Houston TX channels on my TVs...
>>  The HDHomeRuns cannot tune them..  Thjis is current with a TV and
>> HDHR off of the same "split" antenna run..
>
> You might consider (for investigative purposes) try to obtain the
> sensitivity for both receivers.
>
> Do the manuals list this in the back of the user manuals in the tech
> specifications?

Ironically, the HDHomeRun manuals are for crap..  They have nice
pictures, but nothing useful..  Oh well, Like I said, removing the
"certified" installer's splitter and replacing it fixed all of my
local channel problems - even if I cannot tune all of the same
channels my TV can on the same cable..

It can tune all of the locals for here though..

-Greg


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