[mythtv-users] Indoor HD antenna question
bertaboy at gmail.com
Tue Apr 17 17:15:07 UTC 2018
On Thu, Apr 12, 2018 at 5:05 PM, Barry Martin <barry3martin at gmail.com>
> Both antennas feed into a VHF/UHF combiner (e.g. Radioshack # 1502586https://www.radioshack.com/products/radioshack-vhf-uhf-gold-plated-splitter-combiner
> I'll preface with a "YYMV" ('your mileage may vary') disclaimer. As I
> mentioned in my original reply, the channels reported by the digital
> station now are not accurate as to what their actual broadcast is. A
> station which during the NTSC (analog) era as "Channel 6" was transmitting
> at RF 6 on the VHF band. Now with ATSC (digital) "Channel 6" keeps that
> nickname because that's what 'everybody' knows it as but they really
> transmit at RF 36, a UHF frequency. (It just so happens 6 went to 36.)
> OTOH locally Channel 4 stayed at RF4, so they were NTSC RF 4 and now ATSC
> still RF 4.
> IOW don't go by their 'nickname' for trying to figure out their
> frequencies nor bands. Wikipedia, TVFool, etc., will give the information
> you need.
> With that introduction and reminder, here Channel 4 (transmits at VHF
> RF4) is literally 2 miles to my NE. The rest of the local stations are at
> an antenna farm 17 miles SSE. To receive Channel 4 I needed to "split the
> line" and add a rabbit ear antenna. So I inserted a trusty 2-way
> splitter/combiner, which worked to get Channel 4 but did some weird stuff
> to the UHF stations. Tried a different 2x; still wrong. Eventually found
> out it's not a good idea to use a splitter/ splitter-combiner/etc. to add
> together signals from a VHF antenna and a UHF antenna. One wants a
> "Diplexer" which (apparently) is also known as a "UVSJ" or "UHF VHF
> Separator Joiner". That fixed my reception problem! The UVSJ looks
> similar to the TV Accessories Department 2x splitter but instead of passing
> everything (VHF and UHF) one connector passes only VHF signals and the
> other only UHF signals into the coax to your TVs/MythTV, etc. (There's a
> similar one for OTA and Satellite - wrong option.
> Now, I'm not stating the Radio Shack Splitter/Combiner is wrong, I'm just
> saying for _my_ application it was wrong and just wanted to let you know of
> the possibility. If you have a junk box you might have one already: there
> were devices sold with the rabbit-ear-and-bow-tie (or circular) antenna
> that had inputs marked "VHF" and "UHF" -- the screw terminals on the back
> of an TV is probably a diplexer.
Right, I have a channel that is actually on RF12, which is why I'm using a
VHF-UHF combiner, aka UVSJ (UFH VHF Separator Combiner). It has frequency
filters and is not an arbitrary line splitter/combiner. There's nothing
that says that an UVSJ has to be limited to one direction.
BTW, TVFool has been all FUBAR'ed ever since the FCC began moving down its
repacking plan. Other alternatives exist with more complete data sets.
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