Question: Poor reception on my favorite channel only!!

Marvin

DTVUSA Jr. Member
#1
My 1st post. Hope the tvfool info works.

TV Fool


I have had a record of occasional reception problems for our local Chicago PBS station, WTTW Channel 11 which broadcasts on RF channel 47. It has been stable for months, but recently drops out very often.

Most Chicago stations broadcast from the Willis Tower, and all of them are very stable, even other channels closest to the channel 47 frequency (WTTW).

Are there equipment faults (poor connections, cables, etc.) or reception problems that will affect only one channel?

Here is the hardware/cabling chain:
I am using an earlier version similar to Denny's EZ HD antenna: EZ-HD TV Antenna - Denny's Antenna

with Winegard Preamp AP 8700, 35' RG6 cable, ground block, 10' RG6, Winegard PS 1503 power inserter/power supply, 45' RG 59 (conduit size limitations) to JVC TV.

One peculiarity: The preamp power supply is labeled 18vdc output. It measures 24.5 vdc at the xfrmr, but it is about 15vdc after the inserter. I can measure the 15vdc at all points except at the preamp terminal on the mast. That final cable leading to the mast does test good for continuity, but I get no voltage reading at the preamp. Still, the system does boost the signal.
The preamp system does boost signal level on the TV display by approximately 20. Most stations are in the 80-90+ range. Still, even though WTTW has a 80-90 level like the others, it has frequent signal loss!?!?:mad:

Can't figure it out. Any help appreciated. The station is unwatch-able lately, and of course it is the one we watch the most.

Thanks,
Marvin
 

MrPogi

Moderator, , Webmaster of Cache Free TV
Staff member
#2
That's a puzzler. I suspect that it may be multipath - have you tried re-aiming or moving our antenna?

I assume you are looking to watch "Create" since it's not a subchannel of the other PBS stations you get. One of our PBS channels dropped Create recently. I still have Create from Idaho PBS as part of their "Learn" subchannel, but others further south of me aren't so lucky.
 

Marvin

DTVUSA Jr. Member
#3
I have tried rotating the antenna 10 or 20 degrees both ways off axis. It helped just a bit at 5-10 degrees off axis, but still had drop outs. If I rotated more than that, then I began to lose channel 7 while not improving channel 11 at all.

The problem is on all WTTW channels: 11-1, 11-2, 11-3. I don't use 11-4.
 

MrPogi

Moderator, , Webmaster of Cache Free TV
Staff member
#4
Denny's antenna is really an RCA 751.
All I can think of is to try moving the antenna rather than just re-aiming. Also, what happens if you pull the pre-amp and power injector out?

I'm hoping others on the forum have suggestions, too.
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#5
:welcome: Marvin

You could try raising and lowering your antenna. Sometimes 6" up OR DOWN can make a world of difference in your reception.

Jim
 
#6
Try raising/lowering the antenna in 6" increments. It may be sitting in a dead zone for that particular frequency. This is very common, even with strong signals. Adjusting aim will not address this issue.

Oops, Fringe Reception beat me to it!!
 
Last edited:

Marvin

DTVUSA Jr. Member
#7
Try raising/lowering the antenna in 6" increments. It may be sitting in a dead zone for that particular frequency. This is very common, even with strong signals. Adjusting aim will not address this issue.

Oops, Fringe Reception beat me to it!!
I had tried raising the antenna before my 1st post, but there was only room to go up about 3 inches. I will try moving it down a couple steps.

It still baffles me why it suddenly began to deteriorate badly. Either something is obstructing the signal that was not there before, or some component is failing. Whatever it is, it only affects channel 11
 

MrPogi

Moderator, , Webmaster of Cache Free TV
Staff member
#8
It still baffles me why it suddenly began to deteriorate badly. Either something is obstructing the signal that was not there before, or some component is failing. Whatever it is, it only affects channel 11
If you try the tricks we suggest with no results, you may want to contact the station and ask if anything has changed on their end.

Trip may know something about this, too. Lets see if he swings by...
 
#9
Your symptom is of the antenna being in a dead spot due to multipath. As suggested, move it somewhere else and try again.

Usually, when a previously stable setup develops this issue, it's because the environment around the antenna has changed, often due to the gradual growth of trees or, occasionally, tree damage from storms, or even new building construction in the area.
 

Jim5506

DTVUSA Member
#10
You are only 20 miles from the towers, do you really need that 17dB pre-amp, your signal may be momentarily overloading.

An additional 17dB along with antenna gain onto the 60dB or so in the air that's a lot of signal.
 

dkreichen1968

Moderator
Staff member
#11
I agree with Jim5506. TVfool gives 54 dB of signal in the air for channel 11, and the ANT751 has 5 dB of gain, which gives you 60 dB of signal before you add the amp. Overload is a very real possiblity, and can cause the reception problems you're describing.
 

Marvin

DTVUSA Jr. Member
#14
SOLVED !! Hopefully.......

Since I first posted, my reception on channel 11 has deteriorated to zero.

Two days ago I tried moving the antenna 6-8" down from its original position, changed channels back to 11, and it came on like switching on a light! I was hoping it would help, but was surprised when that small position change made such a dramatic difference.

We watched for 45 minutes w/o a glitch, but then saw a very minor momentary pixelation, followed later by a more prolonged episode that discouraged watching. Next day it was better, but still occasional drop outs. Today, I lowered the antenna another 6 inches. The reception now seems good, the signal meter is more stable, but does vary in a range from 81-94, but thankfully no drop outs so far. :grin: We may not be fully tuned in yet, but certainly are moving in the right direction.

Thanks to all for your input, particularly those who suggested adjusting the antenna height--simple but effective. I was at a loss what to do next. You have been very helpful.

Here is a pic of my antenna. I think it is larger than Denny's current EZ HD model. The antenna was originally positioned near the top of the mast. It is performing at its recent best in the position in the photo.

IMG_20130628_201007.jpg
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#15
...

Two days ago I tried moving the antenna 6-8" down from its original position, changed channels back to 11, and it came on like switching on a light! I was hoping it would help, but was surprised when that small position change made such a dramatic difference.

... I lowered the antenna another 6 inches. The reception now seems good, the signal meter is more stable, but does vary in a range from 81-94, but thankfully no drop outs so far. :grin: We may not be fully tuned in yet, but certainly are moving in the right direction.

Thanks to all for your input, particularly those who suggested adjusting the antenna height--simple but effective. I was at a loss what to do next. You have been very helpful.
Marvin, Forum members here have 'been there-done that' and we don't like to lose! Still suggested would be to 'walk' your antenna to other locations that might be better than its current location. Glad we helped.

Jim et al.
 
Top