[mythtv-users] HELP! In antenna hell!
Douglas_Peale at comcast.net
Wed Sep 29 18:30:14 UTC 2010
On 09/29/2010 11:14 AM, Richard Shaw wrote:
> Ok, brief history:
> My original setup (prior to DTV transition completion) was a
> HDHomerun w/ both tuners (ATSC) connected to a single DB2 UHF
> antenna. Everything was fine as even the VHF broadcasters where
> using UHF channels for their digital TV broadcasts. I would have
> occasional hickups in the signals, some more than others, but
> all-in-all everything was fine.
> Once analog TV was dead, two of the networks moved down to their
> original analog frequency: 5 & 13. I was able to get 13 OK with my UHF
> antenna but I could no longer get channel 5.
> Fast forward to last week when I finally bought a CS-600 VHF
> antenna and Channel Master UHF/VHF UVSJ. I put both antennas on my
> 5' mast as far as I could apart in the attic as I really don't want to
> mess with an external mast and I think it would violate my
> neighborhood covenant.
If you are in the US, and you own your roof, the FCC overrules all homeowners association rules and CC&Rs. You CAN put your
> Now I barely get 5 even though on the HDHR I'm
> getting 100% signal strength but only 50-60% signal quality and the
> symbol quality drops frequently and channel 51 is all over the place
> when it was solid before.
> I tried moving things around in the attic while taking my netbook up
> with me check signal strength (via hdhomerun_config_gui). I'm getting
> 80%+ signal strength in every case and in most cases 100%. I
> intentionally over sized my antennas to make up for the fact they were
> in the attic. It seems that the signal was much better while I was up
> in the attic with the antennas.
> I wonder if I could just hire someone to stand up there 24/7? :)
> Now the VHF antenna is laying on the attic floor and the UHF is up as
> high as I can get it. I tried moving both the antennas all around
> including upside-down, facing down, facing away from the broadcast
> towers, everything while watching the signal strength/quality and
> nothing had a noticeable effect except getting the UHF antenna close
> vertically to the VHF antenna and it only seemed to affect the VHF
> antenna. Horizontal separation did not appear to help.
> Googling quite a bit I've read I need a minimum of 3 feet separating
> the antennas but another site said 5 and then another said twice the
> wavelength (or was it 2 times the quarter wavelength?) i.e. twice the
> longest element in the antenna which would be 2 x 80" which I'm not
> even sure I could accomplish in my attic.
> This makes my wonder. If I need so much separation, how do combined
> UHF/VHF antennas work?
> Here's what I'm thinking of doing next:
> - Adjusting the antenna locations then coming back down from the attic
> to get measurements of signal quality without me interfering with (or
> improving as the case may be) the reception.
> - Upgrading to RG6 quad shielded cables or maybe even RG11 but I don't
> think that will magically solve my problem. Currently I've got 25'
> RG59 to the UVSJ and RG6 going from the UVSJ to each antenna.
> Any useful/practical advice would be greatly appreciated.
>  http://www.antennasdirect.com/store/DB2_antenna.html
>  http://www.antennacraft.net/CS.html
A better place to look for antenna advice is avsforum.com. There should be a page specific to your location. TVFool.com is also
useful for antenna issues.
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