Hmmm... The time zone shows that you're in +1100 which I would
guess(tm) is south-eastern Australia on DST. Is that correct?
If so, much of what I said may not apply as the TV and cellular
standards might be different. I know zero about those for Australia
and therefore suggest you find a local source of technical help.
>OTA?
OTA = Over The Air as in broadcast TV.
>The TV has an aerial with no amplifier, with
>a coax cable. The assy is shown here.....
>
https://postimg.cc/XGG83TfM
>The top set have been disconnected because they're
>too high to reach, so the TV runs on the bottom
>one.
I see a few problems.
1. You are well below the main lobes of the cellular antennas on the
nearby roof but close enough that you are going to see problems
created by all the transmitters.
2. Running the 3 guy wires through the elements of the lower antenna
will have a detrimental effect on the antenna pattern and gain. I
suggest you remove the galvanized guy wires and replace them with a
non-conductive equivalent such as a UV resistant polyester or kevlar
guy wires.
3, The mast clamp, where the 3 guy wires meet, is heavily rusted.
This is normally not a problem. However, in a high RF field
environment, rusted metal can produce a diode junction, which will mix
two or more signals or their harmonics to produce what is called
intermodulation. This intermodulation is a possible source of your
alleged interference. You can temporarily fix a problem cause by a
rusty connection by simply beating on the mast with a hammer to break
through the rust. However, given time and weather, it will be back. I
suggest you replace the clamp with something that is hot dip
galvanized or plastic insulated.
4. The unused upper antenna appears to include a small UHF antenna
below the main VHF antenna. I only see a single coaxial cable, but no
VHF/UHF band splitter. If you eventually resurrect the upper antenna,
you might check if it's wired properly.
5. Thank you for the nice photo of the upper antenna, which is not
being used, but only part of the lower antenna, which is being used. I
wanted to see the feed point of the lower antenna, which was cut off.
Also, I can barely see half of what might be a UHF element on the
front of the lower antenna.
>>>Worse on some channels.
>>
>>Which channels?
>
>All channels, though the lower-freq ones are
>worse.
Improbable. There are no jammers or signal sources that can wipe out
the entire TV spectrum. For Australia DTV, that would be 694-820 MHz.
<
https://www.communications.gov.au/what-we-do/spectrum/digital-dividend-spectrum>
Certainly not interference caused by a cellular transmitter, which
would be far more noticeable on the higher channels than the lower.
It's possible that there is so much RF that the front end of your
unspecified model Sony TV receiver is being overload. This is called
"blocking" where the high RF level is rectified by the amplifying
devices in the front end of the receiver, causing the biasing of the
devices to change, and generally reducing its gain. This would reduce
the receiver sensitivity on all channels, as you describe. However,
unless something in the antenna farm is running really high power, or
your unspecified model Sony TV receiver is poorly designed, such
blocking is improbable. (Possible, but not likely).
>>Are you sure you didn't do anything to make it go away? Antenna
>>connection? Loose shield on the RG-6/u coax cable? Nearby noise
>>source got turned off? I once disarmed a "negative ion generator"
>>that was wiping out OTA TV reception in part of an apartment building.
>
>No. It all just stopped.
Well, I see three possibilities:
1. Your antenna and/or coaxial cable system is intermittent due to
either a short across the coax, or a bad connection on the center pin
or shield. It could be anywhere but most likely at the connector
ends. Also, look for "U" staples punching through the coax cable.
2. Your TV has a problem. Test with by borrowing another TV and
comparing. If only your TV has the problem, the culprit is obvious.
3. A fairly high power cellular transmitter nearby was turned off.
>A good point, so next time it happens I'll put it
>up into the maid's room, and buy a
>newone..especially since these have greater
>functionallity for movie formats.
Is there some reason why you have failed twice to provide the model
number of your 2006 Sony TV?
I'm not familiar with that product. It will tell you if you have a
signal in the TV band, but will not tell you on what channel, or
whether it's a TV transmitter or cellular transmitter.
>Thank you.
>I can always use a bit of luck.
You're welcome. However, there's a problem. You're doing a splendid
job of obscuring your information and ignoring my questions. This is
YOUR problem, not mine. I'm trying to help, but making me do extra
work by having to guess your location, your TV model, and your
relative position to the likely source of interference, is not being
very cooperative or helpful. When you see a sentence end in a
question mark, please try to answer the question.