Occasional vibrating blocks on channels 33-35

Thirstyrock · 1-Dec-2016, 3:54 PM

(Phoenix, AZ. 85053) I have an Antennas Direct DB8 installed outside on a 25' pole. Quad shielded RG-6 Cable also. The only channels I seem to have problems with is the channels in the 33-35 range where I occasionally get giggling blocks that appear than diasappear. There is nothing blocking the line of sight to towers and cable as well as antenna mast are grounded. I did notice I get channels above the 51 group. Like 61.1, 61.2 etc. which I thought was were not to existant anymore which also seem the shows are broadcasting on lower channels also. I have rotated the antenna several times and no luck on those channels in the 33/35 range. Any ideas please would be greatly appreciated.

GroundUrMast · 1-Dec-2016, 10:35 PM

The displayed channel number is a virtual number and in most cases, not the physical channel number. Please post a link to your TV Fool report (that includes the real channel number which is what the antenna system has to deal with).

ADTech · 1-Dec-2016, 10:53 PM

Do you have an amplifier installed? If so, remove it as your signals are very strong and amplifying them will cause your specific symptom (or others).

Otherwise, try the following as needed:

1. Adjust the antenna so that it is aimed with the bowties (whiskers) so they are perpendicular to the direction of South Mountain.

2. Raise or lower the antenna in 12" increments, if possible.

3. Move the antenna and try again. Do not drill any new holes until you've found a spot where the signals cooperate with the antenna.

If your TV set has a signal meter function, try to observe (and then report) how it behaves when you have that pixelization.

rabbit73 · 1-Dec-2016, 11:20 PM

I agree; very strong signals on generic report for your zip code.

http://www.tvfool.com/?option=com_wr...dfaf64ad972c00

The generic report is centered on 33.628995,-112.13706
Phoenix Arizona Paranormal Society
W Tierra Buena Ln and N 36th Pl

which might not be close to your actual location.

The local FM signals are also very strong at that location
http://www.fmfool.com/modeling/tmp/c...4/Radar-FM.png

Thirstyrock · 4-Dec-2016, 1:08 AM

Attached Generic TVFOOL Signal Analysis
http://www.tvfool.com/?option=com_wr...dfaf97cdb86b5e

NO Amplifier attached to antenna.

WIRELESS ENGINEER · 5-Dec-2016, 7:57 PM

The db8 isn't the best performer in 8 bays at channels 35 and below but the chart shows signal levels so strong you should be able to pick them up on rabbit ears

Double check coax fittings

Receiver desense from nearby radio transmitters is always a possibility as well as desense from LTE cell service and white space use

Things like unlicensed wireless outside thermometers can easily desense a TV receiver and cause brief picture break up

rabbit73 · 5-Dec-2016, 8:10 PM

Thank you for the new report. Your TV and FM signals are still very strong.
FM
http://www.fmfool.com/modeling/tmp/3...3/Radar-FM.png

In addition to following the advice by ADTech, I suggest you try inserting an attenuator in the coax line between the antenna and the tuner to see if overload is a problem. Also try inserting an FM filter to attenuate your local FM signals.

A splitter can be used as an attenuator; 3 dB for a 2-way splitter, 7 dB for a 4-way splitter. There is also a variable attenuator available:
https://www.antennasdirect.com/store...ttenuator.html

The ATT-1 knob has 3-3/4 turns, so I put a mark on the knob with an ultra fine point Sharpie to count the turns. Clockwise rotation increases the signal; minimum attenuation at full clockwise rotation. When I use mine to make tuner sensitivity tests, I start there, and rotate the knob counterclockwise to increase the attenuation for the test.
http://www.avsforum.com/forum/186-co...l#post48473881

You can try this FM filter

https://www.antennasdirect.com/store...on_filter.html

or use a HLSJ as an FM filter, which blocks everything below CH7, including the FM band.
http://www.solidsignal.com/pview.asp?p=zhlsj

WITRELESS ENGINEER has a good point about possible cell tower interference.

Thirstyrock · 5-Dec-2016, 10:11 PM

Hooked up a Channel Master LTE Filter to back of TV with Antenna cable running to it. Nothing changed. I have come to relize that there are 2 channels that are atrocious and funny thing is they both appear great on the corresponding channel 61..... Example: Channel 35.4 (Escape Channel) blocks frequently yet if I turn to 61.4 (Escape Channel-same program running) no blocking and nice picture. Also channel 33.3 (Grit) same problem blocking frequently yet it is also showing on 61.3 ok, same program.....
Humm why would I be receiving in both places? And I thought that channel master filter was suppose to block channels in the 60+ range.

Well maybe just watch on the 61 band...lol and delete from the other 2 channels

ADTech · 5-Dec-2016, 10:40 PM

You're misunderstanding virtual vs real channels. It is the "real" channel information that's important. Your TVFool chart shows both of them.

Thirstyrock · 5-Dec-2016, 11:17 PM

I pick up both channels. I scan with tv and get 61.1, 61.2.61.3, 61.4 also added along with the 33.3 and 35.4 channel and they have shows on them as well as them showing on the channels formentioned. Yes I actually have a physical channel 61.1., 61.2, 61.3, 61.4 that I get listed in my list that the tv scans and finds, not virtual channel.
I understand these should not exist and be on a virtual channel which they are also simultaneously on a virtual channel I.E. 33.3 and 35.4.
I hope I clarified that somewhat. The problem is the Virtual Channel is the one that is getting blocking frequently. 33.3 and 35.4

rabbit73 · 6-Dec-2016, 1:33 AM

You still don't have it right.

The real channel is the same as the physical channel. It is the RF channel that the transmitter uses.

The virtual channel is the same as the display channel on the TV. It may or may not be the same as the real channel because it is a holdover from the analog days to maintain the identity of the station.

There are no real/physical channels higher than 51. It is possible that your tuner memory has become corrupted, in which case you can clear it with a double rescan. The other possibility is tuner overload.

Grit is supposed to be on KTVW real channel 33, virtual channel 33.3 AND on KASW real channel 49, virtual channel 61.3.

Escape is supposed to be on KASW real channel 49, virtual channel 61.4 AND on KFPH real channel 35, virtual channel 35.4.

Tower Guy · 6-Dec-2016, 1:46 PM

Quote:

Originally Posted by Thirstyrock

(Phoenix, AZ. 85053) I did notice I get channels above the 51 group. Like 61.1, 61.2 etc. which I thought was were not to existant anymore which also seem the shows are broadcasting on lower channels also. I have rotated the antenna several times and no luck on those channels in the 33/35 range. Any ideas please would be greatly appreciated.

Perhaps your TV has locked on to one of the low power stations instead of the real 33 and 35. Try manually deleting 33 and or 35 and see if they get replaced by the stronger stations that are mapped to 61.