TV Fool  

Go Back   TV Fool > Over The Air Services > Help With Reception

Notices

Reply
 
Thread Tools
Old 18-Feb-2017, 9:08 PM   #1
mmbuckwa
Junior Member
 
Join Date: Feb 2012
Posts: 12
Losing reception

Here is my TV signal analysis.

http://www.tvfool.com/?option=com_wr...e6a42cb6f1688d


In the past month my PBS station, WITF 33.1, is becoming hard to receive with my winegard HD7694P antenna. Most of the time the TV screen is dead, but sometimes I get reception or broken pixels. I emailed the station asking if they changed their broadcast signal but got no response. I have heard of certain channels selling bandwith to the wireless internet providers but not sure if that is an issue. My question is, is there an antenna that will do a better job of pulling in this station. All of the other channels I receive (8.1, 15.1, 21.1, 27.1, 43.1, 49.1) are unaffected. Thanks.
mmbuckwa is offline   Reply With Quote
Old 18-Feb-2017, 11:04 PM   #2
rabbit73
Retired A/V Tech
 
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,248
In your previous thread you said:
Quote:
Originally Posted by mmbuckwa View Post
Looking to get over the air tv at my location and would appreciate any help with antenna purchase and installation. NBC comes in with rabbit ears but PBS is a must for me and it appears to be the most difficult station to pull in. There is lots of tall trees in my neighborhood that probably won't help, thanks.
Is it possible that the trees are getting worse in the direction of PBS? Trees block TV signals.

Is 12 feet the best you can do for antenna height?

Exactly what direction is your 7694 antenna aimed? Can you show us a photo of what the antenna "sees" when it is aimed at PBS (307 degrees true, 319 degrees magnetic)?

WITF PBS, real channel 36, virtual channel 33.1 is your weakest desired channel. WHP CBS is in the same direction, but it is almost 10 dB stronger; PBS needs all the help it can get. Unfortunately its azimuth is between two stronger stations, at around 270 and 336 degrees true.

The advice that you were given previously wasn't really bad, because you need an antenna with a wide beamwidth, but the problem is that real channels 23 and 47 are almost 50 dB stronger than PBS. If you try to add a preamp to make PBS stronger, it might be overloaded by WXBU and WPMT. It might also cause tuner overload, but you could insert an attenuator after the preamp power inserter to prevent that. You could try to add a medium gain preamp like the Antennas Direct Juice and see what happens.

An alternative would be a CM3410 further down the coax.

Another problem for your location is that you have some strong local FM transmitters that might interfere with TV reception, but an FM filter would help.
http://www.fmfool.com/modeling/tmp/2...6/Radar-FM.png

Another possible solution would be to use an antenna with a narrow bamwidth that puts a null on each side of its aim to make the stronger signals weaker, but then you might have to add a VHF antenna for ABC.
__________________
If you can not measure it, you can not improve it.
Lord Kelvin, 1883
http://www.megalithia.com/elect/aeri...ttpoorman.html

Last edited by rabbit73; 19-Feb-2017 at 12:16 AM.
rabbit73 is offline   Reply With Quote
Old 19-Feb-2017, 12:07 AM   #3
mmbuckwa
Junior Member
 
Join Date: Feb 2012
Posts: 12
I aimed the HD7694P at 310 degrees and have the CM3410 installed before the cable goes into the TV. This set up has worked great for five years and now channel 33 is gone in the last month. Just curious why it quite working now. There are trees but they haven't affected it before and right now there are no leaves so it seems strange that would be a factor this time of year. Thank you for replying to my thread. If there is an antenna that may work better, what would you recommend?
mmbuckwa is offline   Reply With Quote
Old 19-Feb-2017, 12:20 AM   #4
rabbit73
Retired A/V Tech
 
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,248
Sounds like you have made some good tests already.

310 deg true or 310 magnetic?

I'm not certain another antenna would help unless we figure out why PBS is weaker.

Are you using a splitter after the 3410 for more than one TV?
__________________
If you can not measure it, you can not improve it.
Lord Kelvin, 1883
http://www.megalithia.com/elect/aeri...ttpoorman.html

Last edited by rabbit73; 19-Feb-2017 at 12:23 AM.
rabbit73 is offline   Reply With Quote
Old 19-Feb-2017, 12:33 AM   #5
mmbuckwa
Junior Member
 
Join Date: Feb 2012
Posts: 12
I was up on the roof today and I set the compass needle on north with the zero at the the north needle. Then aimed the antenna at 310 the best I could by eye. It was a little off before but turning the antenna a little to the right did not produce any difference in reception. I use a splitter after the 3410 for two tv's and one into my receiver for FM radio reception. This is the same set up I've been using for five years. Is the antenna direct juice a better amp than the cm 3410? I will look for some reviews about it online. Thank you.
mmbuckwa is offline   Reply With Quote
Old 19-Feb-2017, 2:08 AM   #6
rabbit73
Retired A/V Tech
 
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,248
Quote:
I use a splitter after the 3410 for two tv's and one into my receiver for FM radio reception.
What happens if you connect the output of the 3410 directly to one TV, bypassing the splitter?

Both amps are resistant to overload; the Juice has a little more gain. Stick with the 3410 for now.

This might work, but you would need to add a VHF antenna for VHF-High and FM. You could use the 7694 as a test for that and combine it with the 91XG (or HDB91X) with a UVSJ:

Attached Images
File Type: jpg mmbuckwaTVFpattern.JPG (147.1 KB, 370 views)
__________________
If you can not measure it, you can not improve it.
Lord Kelvin, 1883
http://www.megalithia.com/elect/aeri...ttpoorman.html
rabbit73 is offline   Reply With Quote
Old 19-Feb-2017, 12:51 PM   #7
ADTech
Antennas Direct Tech Supp
 
Join Date: Jan 2010
Posts: 2,830
Quote:
This set up has worked great for five years and now channel 33 is gone in the last month. Just curious why it quite working now. There are trees but they haven't affected it before and right now there are no leaves so it seems strange that would be a factor this time of year.
Trees are growing continuously, even in the winter when the growth is imperceptible.

Reception problems caused by trees is usually seasonal with reception improving when the leaves drop in the fall and then degrading again when the leaves return again in the spring. However (and this is important in YOUR case), reception problems can return as early as January or whenever the sap starts running back to the trees' extremities in mid to late winter. It is the water content in the trunks, branches, limbs, and twigs that shred the incoming signals, the trees are simply the conduit for the water.

Due to the cliff effect that is characteristic of digital reception, a signal that just happens to be near the edge of the cliff but is received "perfectly" doesn't require much more degradation for it to get pushed off the cliff.

Fixing your particular problem is usually pretty straight forward - either move the antenna or move the trees. The second is often not feasible and, for the first, you usually will find that fixing one station's reception sometimes damages another so patience is required.

Adding an amp is usually a Band Aid that sometimes works if the underlying cause is simple signal attenuation caused by trees. But, reception behind trees is rarely that simple. Sometimes, swapping to a different antenna that has a different reception aperture can provide relief. In either case, the improvement is often of a temporary nature since, as I already mentioned, trees are ALWAYS growing.

Understanding the underlying issue is usually important in resolving the problem.

Best of luck!
__________________
Antennas Direct Tech Support

For support and recommendations regarding our products, please contact us directly at https://www.antennasdirect.com/customer-service.html

Sorry, I'm not a mod and cannot assist with your site registration.
ADTech is offline   Reply With Quote
Old 19-Feb-2017, 2:13 PM   #8
rabbit73
Retired A/V Tech
 
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,248
Good advice from ADTech. If trees are in the signal path, they will always be a problem. There is no magic antenna that will see through trees as if they weren't there.

If PBS is really important to you, make a temporary test with a UHF antenna set up in the clear to see what might be possible. If it does well, it can be combined with your 7694 for the other channels using a custom ch 36 combiner.

http://www.tinlee.com/PDF/AC7-custom...kup%20Info.pdf

http://www.tinlee.com/MATV_headend.php?active=4

A less expensive version from Jan Jenca who sells on ebay:



http://www.ebay.com/itm/Selective-co...item1c6d4d6faa

http://www.antenne-komponenty.eu/eng...zlucovace.html

Another approach is a selective amplifier for ch 36:



http://www.ebay.com/itm/UHF-selectiv...item1c6483bd0a
Attached Images
File Type: jpg Selective Channel Preamp_1.jpg (90.3 KB, 335 views)
__________________
If you can not measure it, you can not improve it.
Lord Kelvin, 1883
http://www.megalithia.com/elect/aeri...ttpoorman.html

Last edited by rabbit73; 19-Feb-2017 at 3:43 PM.
rabbit73 is offline   Reply With Quote
Old 20-Feb-2017, 11:51 AM   #9
mmbuckwa
Junior Member
 
Join Date: Feb 2012
Posts: 12
Thanks ADTech and rabbit73 for giving me options and taking time to explain how this technology works.
mmbuckwa is offline   Reply With Quote
Old 20-Feb-2017, 2:04 PM   #10
rickbb
Senior Member
 
Join Date: Dec 2014
Posts: 273
If it's worked well for 5 years and suddenly started this you should check all your connections and the cable. Connections can corrode, cable can get broken or chewed by squirrels, mice, etc. Or just have the insulation dry out from sun exposure.
rickbb is offline   Reply With Quote
Old 21-Feb-2017, 2:23 AM   #11
WIRELESS ENGINEER
Senior Member
 
Join Date: Dec 2013
Location: Eastern Ohio
Posts: 101
since its in the middle of winter in Lancaster pa, I doubt tree growth is an issue right now

more likely you have a connection issue

either the antenna balun isn't making as good a connection as before due to oxidation or a bad coax connection

if the outdoor connections were not made air tight, you may have moisture penetration that caused contamination or corrosion

UHF frequencies are very susceptible to even slightest amount of condensation or oxidation in a connector

do not use copper plated steel center conductor coax
I've witnessed rust develop that can contaminate the dielectric of the coax and the antenna balun

buy only SOLID bare copper center conductor RG6

I have a 16,000 dollar spectrum analyzer I use on the bench and a 6,000 dollar Anrisu site master I use in the field for finding interference sources and I can tell you that
these days the amount of interference sources that affect TV reception goes far beyond just FM broadcast

All areas now have LTE cell towers that use the lower end of The 700 MHz band

Most new 911 radio networks have now moved to the 700 MHz band so their repeater towers are now causing interference all over the nation

amplifiers like the cm3410 only make it worse since they just amplify the interference along with the TV signal

Tv manufacturers put very little money into their tuners so they can easily be desensed by police, fire, business,paging systems,ham radio, wireless thermometers, etc etc etc

in the old days you could easily tell what the source of interference was by looking at the picture

but now it takes a professional who knows how to use a spectrum analyzer
WIRELESS ENGINEER is offline   Reply With Quote
Reply

Bookmarks

Go Back   TV Fool > Over The Air Services > Help With Reception


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off




All times are GMT. The time now is 1:06 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Copyright © TV Fool, LLC