Question: ABC reception problems - experts please help

yetidtv

DTVUSA Rookie
#1
OK, so I have put a fair amount into my DTV OTA system in an attempt to cut the link to cable for good. All is well EXCEPT for one channel - WABC. This is a key channel in my house so I need it, but have been totally defeated as to why it is not working.

Here are the basics of the issue - I get the channel fine, just not consistently. Yes, I know that sounds weird. The signal for this station comes in at 70-80% strength but will then drop out, sometimes for a second and sometimes for several minutes or more. All the other channels work fine (although one other channel 11.1, which is also VHF, has also very occasionally had a few hiccups). In all though, it really comes down to this channel. There is no particular time it does this that I can tell, although nights may be worse (it may also just be when the wife is watching and getting frustrated).

Here is my setup to go with the tvfool link on my location:
* I live 5 miles from the transmitter in NYC. Details in the link above
* I have a Channel Master 2016 antenna - see here - mounted on an 8 foot pole on top of a 3 story apartment building.
* I am putting this through a modern ATSC tuner (I've tried 3 different tuners, all have the same problem)
* it is a single line from the antenna, across the roof, through the wall and into my apartment (I live on the top floor) - probably a 50 foot run but all with good condition cable
* I tried a signal attenuator (station drops out worse) and an FM trap (does nothing) - I also tried a line amp but (and I knew this before I put it on) it just magnifies the problem.

I'm <5 miles from a powerful transmitter with a decent antenna pointed right at the tower (have not taken the compass up, but darn close). I can understand multipath issues, but don't know why the attenuator would not have helped. The net here is that I am totally lost. If anyone can solve this with a snap of their fingers I'd be eternally grateful. I'll also take additional directions to look in...:becky:

Thanks in advance for your help
 

re_nelson

DTVUSA Member
#2
OK, so I have put a fair amount into my DTV OTA system in an attempt to cut the link to cable for good. All is well EXCEPT for one channel - WABC. This is a key channel in my house so I need it, but have been totally defeated as to why it is not working.
1). Can you actually see the ESB from the antenna mount point?

2). What kind of buildings do you have east of your Astoria location that might be reflective?

Based upon your TV Fool chart and your very thorough report, I surmise that you're the victim of multipath from WABC's hot signal on the backside. The CM2016 doesn't *appear* to have a very good front-back ratio on the VHF side.

I'll defer to other experts who may expand on (or even refute) my contention that multipath is at play.

One more quick question -- how did WABC come in OTA back when it was still analog? Was there much ghosting?
 

yetidtv

DTVUSA Rookie
#3
Thanks for the the reply:

1. no, I don't think it is pure line of sight

2. I don't live near any huge towers, but there are a handful of buildings taller than 3 stories that block the view. The signal also comes from mid town manhattan if I read the chart right (which is west of me) so there are buildings there (even if the empire state bldng should be pretty high relatively speaking). The confounding thing is why other stations have no problems and ABC does

I like your theory on the front back ratio of the antenna. One additional detail - I hooked up a cheap set of rabbit ears near the WEST facing window and it actually pulled in ABC better (although the problem is that it is intermittent, so it could be a fluke). Still, that is what had originally suggested to me that attenuation might help (it doesn't seem to). Unfortunately, I lose other channels with that setup and it does not fit my living space (TV is on the other side of the apartment). What is the solution - an antenna with a better front/back ratio?
 

yetidtv

DTVUSA Rookie
#6
ShowMe: I have two other high VHF channels - 11.1 and 13.1. The former has occasionally shown issues but nothing persistent... it has never been clear if it is just part of traditional OTA dropouts (which I understand will occasionally happen). The antenna is supposed to be good in the VHF band, although I guess it is a possibility that it is not working right or another would do better... not sure if there are also other issues with VHF channels I should consider...

ProjectSH: I bought an FM trap from antenna's direct and hooked it up in line close to the TV receiver. Not sure if I am missing something here - assumed it was plug and play

Lastly, to answer a Q from earlier, I did not have the OTA system when the signal was analog, so I don't know what the reception was like...
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#7
:welcome: yetidtv,
Your test with rabbit ears and the signal quality improvement is telling. The signal breakup could be caused by too much signal. Would it be possible to test your rooftop antenna on the opposite side of the building? Have you tried it at different heights say 5' lower or 5' higher?

I checked with the REC Networks website REC Broadcast Query and WABC transmits with 26.9 kW output (ERP) and they have applied to drop their output to 17kW, and that change may help you.

Another possibility would be to make a Grabbit Ears: GrabBit Ears - The best indoor antenna! although it is primarily designed for UHF, it might work for you. Then, you could use an A-B switch between you indoor and outdoor antennas.

Experimentation is the key. Here is a novel way one fellow resolved his reception issues (2 pages). Key in text the normal way Keep us posted on your results.
Jim
 
Last edited:

Trip

Moderator, , , Webmaster of: Rabbit Ears
Staff member
#9
WABC transmits with 26.9 kW output (ERP) and they have applied to drop their output to 17kW, and that change may help you.
I'm not quite sure how you determined they want to drop power. The 17 kW filing was submitted as an alternative in case the FCC rejected the 26.9 kW STA. The interference agreement they have with WNJB allows them to later increase to 34 kW.

- Trip
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#10
Trip,
I stand corrected: usually, the dates on that site are consecutive. By the way, it was reported on AVS, KOMO is now operational at full power.
Jim
 

Don_M

DTVUSA Member
#12
I'm leaning toward multipath interference as the major culprit. In that location, any tall buildings within about a mile can and will act as reflectors. Reflected signals present a tough situation for any digital tuner. CM's specs show the 2016 to be multi-directional on channels 7-13 (see Channel Beamwidth table at the bottom of this page). Multi-directional antennas by definition have a rather difficult time warding off signal reflections.

As Jim suggests, you may be able to find a sweet spot by raising or lowering the 2016. Turning the antenna might also be advantageous. Try aiming it away from the direction of the ESB; sometimes reception actually improves at an off-angle. But if you spend hours trying different aims and heights, and WABC continues to be hinky -- or, worse, WPIX and/or WNET start getting weird -- then it's time to consider replacing the 2016 with something more directional, as TG just suggested.

Finally, hang on to that FM trap. It may yet come in handy as you live in one of the densest broadcast-signal environments on the planet.
 

SWHouston

Moderator
Staff member
#13
yetidtv,

Tower Guy has made some very good suggestions for a replacement Antenna, I think in addition to those, you should concider...
ANTENNAS DIRECT V-21

Have a good Day ! :)
S.W.
 

re_nelson

DTVUSA Member
#15
I like your theory on the front back ratio of the antenna. One additional detail - I hooked up a cheap set of rabbit ears near the WEST facing window and it actually pulled in ABC better (although the problem is that it is intermittent, so it could be a fluke). Still, that is what had originally suggested to me that attenuation might help (it doesn't seem to). Unfortunately, I lose other channels with that setup and it does not fit my living space (TV is on the other side of the apartment). What is the solution - an antenna with a better front/back ratio?
I'm going to add my vote for the HBU-22 as suggested by Tower Guy simply because it's readily available at Radio Shack. I've had experience with it and it actually HAS a measurable front-back ratio in contrast to the multi-directional (on VHF) CM-2016.

The other obvious advantages with the AntennaCraft HBU-22 are its modest cost, small size and...it can be returned if it doesn't work.

Big boys like the Winegard YA-1713 are overkill -- unless you want to grab the power from WABC/7 and light your whole building! :) :) :)

By all means, keep us posted.
 

yetidtv

DTVUSA Rookie
#16
These are great suggestions - thanks.

After reading through this, I decided to watch channel 11 (my other vhf station) with the signal strength meter on. Turns out, it exhibits the same behavior as ABC/7 but is just much less pronounced so not as noticeable (and I must watch it less as a station). Given this, and from everything you have listed, it seems I have a multipath problem with high-vhf. I had no idea that the 2016 was bad with vhf reflection. I just ordered a HBU-22 - thanks for the recommendation - and will update you when I get it installed.

Thanks again to everyone - hopefully this cures the gremlins.
 

re_nelson

DTVUSA Member
#17
These are great suggestions - thanks.

After reading through this, I decided to watch channel 11 (my other vhf station) with the signal strength meter on. Turns out, it exhibits the same behavior as ABC/7 but is just much less pronounced so not as noticeable (and I must watch it less as a station). Given this, and from everything you have listed, it seems I have a multipath problem with high-vhf. I had no idea that the 2016 was bad with vhf reflection. I just ordered a HBU-22 - thanks for the recommendation - and will update you when I get it installed.

Thanks again to everyone - hopefully this cures the gremlins.
And...if it doesn't work, remember to blame Tower Guy. If it does work well for you, then re_nelson gets all the credit! Yeah...right. :)
 
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