Problem with 38.1 (39) WSBK Boston

#1
I live about 25 miles north of Boston in a poor reception area and can no longer recieve 38.1 which is broadcast on 39. The signal strength bounces between 0 and 100 with no picture or sound most of the time. Sometimes, I get it when the signal is more steady in the weak range. Here is the history. About 25 years ago, I could only recieve the four vhf channels, 2, 4, 5, and 7. So, after consulting with a friend who installs antennas, I installed a large directional Wineguard antenna with a uhf pre-amp (cp-4800). It worked great great! I could then recieve channels 25, 38, 44, and 56. And later 62, and 68. But, now, after the switch to digital, I can't get 38.1. The engineer at wsbk told me that there are no transmission problems. I just ordered the AP-4700 uhf pre-amp and am about to order the Winegard uhf antenna, HD-9032, because all the channels that I watch, according to antenna-web and TV-Fool, are uhf. My antenna brackets are very corroded.

I don't understand why my current system no longer gets 38. (Antenna-web says that I need a large directional antenna with a pre-amp) (AntennaWeb)

I am hoping that my HD-9032 with the AP-4700 will fix 38.1. Thanks for any comments. Here is antenna web's info.

DTV Antenna
Type Call Sign Channel Network City, State Live
Date Compass
Heading Miles
From RF
Channel
* blue
uhf WGBH-DT 2.1 PBS BOSTON, MA 239° 18.7 19
* blue
uhf WBZ-DT 4.1 CBS BOSTON, MA 239° 18.7 30
* blue
uhf WCVB-DT 5.1 ABC BOSTON, MA 239° 18.7 20
* violet
uhf WBPX-DT 68.1 ION BOSTON, MA 235° 18.5 32
* violet
uhf WHDH-DT 7.1 NBC BOSTON, MA 236° 18.0 42
* violet
uhf WMFP-DT 62.1 SAH LAWRENCE, MA 237° 18.4 18
* violet
uhf WFXT-DT 25.1 FOX BOSTON, MA 235° 18.5 31
* violet
uhf WGBX-DT 44.1 PBS BOSTON, MA 239° 18.7 43
Note:
The above listing is a conservative prediction of stations received. Depending on the specifics of your installation, you may be able to receive stations that do not appear in this list.
 

Don_M

DTVUSA Member
#2
:welcome:

Well, that antenna and pre-amp should pull in WSBK for you at 25 miles! It's one of the better UHF antennas out there. It's also very big, so get a friend to help install it if you're going to raise it above the roof. If you're interested in the Boston/Lawrence stations only, it's all the antenna you'll need -- those stations are all UHF.

If this is an outdoor installation, I'd also take a close look at the cable and connectors outside. If the cable is more than a decade old, or you have no idea how long it's been out there, or you notice corrosion on any of the fittings, replace the cable. Moisture getting into the connections can cause short circuits that wreck reception for all but the strongest signals. Given the wet, windy weather you've had in the last week, that could well be the culprit. The salt air in your neck of the woods doesn't help, either.

Please let us know how things work out! :thumb:
 
#3
Don -- Thank you very much for your reply and info. That outside connection is 25 years old and has seen much wind-driven rain. I should probably replace the 50 foot cable rather than be cheap and try to replace just the end. Maybe, I won't even need a new antenna but all the brackets need to be replaced and most of the existing antenna is vhf which I don't need anymore. For the last two years I have been expecting the whole thing to blow down. My chimney is 17 feet in circumference and the 40 year old stainless straps look as good as new. In fact, they are wider than my new replacements.

Thanks again and I will post the results.
 

Don_M

DTVUSA Member
#4
You should definitely replace the cable. At 25 years, it's about a decade beyond the end of its useful life. The outer jacket of a coax cable outdoors eventually develops cracks. While most can't be seen, these cracks are large enough to admit moisture. At that point, the moisture begins to corrode the outer shield. The shield eventually becomes so badly compromised that the two-wire "circuit" between antenna ad TV is broken. Be sure to use black coax when replacing the cable. Black resists UV degradation much better than any other color, particularly white.

At that age, the antenna should be replaced for similar reasons, so go ahead and get the HD-9032. Hold off on the amplifier for now; you may find that you don't need one. That antenna probably has at least four times the gain of the old VHF/UHF combo, so it should be more than capable of serving one or two TVs by itself at 25 miles as long as that gully isn't too terribly deep. My father grew up in North Reading, BTW, and I'm not aware of any hills large enough thereabouts that could cause really deep signal shadows and truly awful reception!
 
#6
Don -- Thanks again for your expert advise. I am definatly going to replace the cable. I already ordered the pre-amp from SolidSignal (I have four TV's) and just noticed their top quality RG-6 cable, 50 feet for $20. It would be easier and quicker for me to go to Wal-Mart or Radio Shack but I am not sure of their quality. The current cable, probably bought at Radio S, did last for 25 years but I did buy something else there that turned out to be crap (the name was something like "micronta". I wonder if it is okay to buy RG-6 cable at RS or WalMart.

Thanks bicker. Now, I know that the 38 tech was not lying to me. :)
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#7
I wonder if it is okay to buy RG-6 cable at RS or WalMart.
------------------------------------------
freemarket,

An Engineer on another Forum did a study of different RG-6 coax brands and he strongly recommends against Radio Shack coax, because he says it is "leaky and lossy". He recommends a name brand like Belden and if possible, he prefers factory installed 'F' fittings.

Also, for outdoor use purchace black not white coax because the white coax covering does not hold up well against ultraviolet radiation (the sun! :flame:).

Jim
 
#8
Thanks Jim, That's good info. I won't take the risk with RS. I just found a 50 foot Belden with water-proof connections for $21. The $10 shipping is a bit steep but a family member told me "get the best".
 

serndipity

DTVUSA Jr. Member
#9
As suggested, replacing the coax is like chicken soup (e.g. won't do you any harm and may do you some good).

However, I'm also located near you in Marblehead and, using a DIY indoor antenna, have no problems solid reception of any of the Boston stations.

Additionally, I'm at sea level, 25 miles from the antenna farm in Needham at a magnetic bearing of 249 degrees, where you are nearer (e.g. 18 miles with a bearing of 239 degrees).

Did you put your specific location into TV Fool

This would provide additional information such as whether you are LOS (line of sight) and the expected signal levels etc. at your specific location.

You may have issues with obstructions etc..

However, the channel 38 antenna shares the same tower as channels 4 and 2 etc. If any stations are problematic, I would have guessed they would have been channels 25 or 56 (e.g. which are still 100% here).

There is a forum that discusses 'Local HDTV Info and Reception' and you will find the Boston OTA discussion at:

United States THREAD INDEX - find your local discussion thread HERE. - AVS Forum

Here you might find additional information pertaining to your specific area.
 
#10
Serndipity -- Thanks for your input.

I am in Lynn near Lynnfield. My chimney antenna is about 20 feet above ground. My magnetic direction to that Needham cluster is 238 degrees and 19 miles (my 25 mile estimate was wrong). About 80 feet from my antenna in the 238 degree direction, the land rises steeply about 20 feet and there is house on top of that. Then, the land rises slowly about another 30 feet over the next 200 yards. When my antenna was 15 feet above ground, uhf was mostly snow. About 25 feet from my antenna at 225 degrees, there is a very large 80 foot tree.

I did give my address to TVFool and have no LOS stations. They all say 2Edge.

4.1 is strong but sometimes drops out for a split second. 56.1 and 62.1 are weak but watchable about 50% of the time. 68.1 is strong along with 2.1, 4.1, 5.1, 7.1, and 25.1

38.1 is blank and the signal level, according to my apex converter, bounces between 0 and 100. Very strange. I am champing at the bit to clean the antenna contacts and replace the cable. :)

I was at Lowes today to buy some u-bolts and got their 50 foot, RCA, RG-6 Quad shield. The connectors look like top quality. I am all primed for a dry, windless day. :)
 

serndipity

DTVUSA Jr. Member
#11
OK, 2 edge reception gets a bit tricky.

Basically, you're near enough to have very good signal strength, but the RF signals are being bent (e.g. refracted by the hill) and you'll have to find them (e.g. a sweet spot).

Solutions could be antenna location, tilting, aiming etc.

Here is an article on how someone in VT, among hilly terrain, was able to receive signals from NY. Note that the antenna wound up at ground level.

Classic Pete: Once More, Out To The DTV Fringe

You should be able to find more info on the subject with a 'google' search.
 

serndipity

DTVUSA Jr. Member
#13
Your bouncing signal could be multi-path distortion....specially the dynamic type caused by moving trees on a windy day. However, it could also be that, although you're generally in an area of strong signals, in your specific location, you have signal blockage (e.g. the hill) and your C/N (e.g. carrier signal to noise) is marginal.

In DTV reception the video and audio quality are independent of signal strength. In other words, you will have perfect reception, even with a low signal level and more signal only improves headroom, not picture quality. However, at a certain point the C/N becomes to low and the reception vanishes (Cliff effect).

BTW, the signal meter is indicating signal quality (e.g. decode errors), not strength.

This is explained in the following from link from the Society of Motion Picture and Television Engineers.

http://sas-origin.onstreammedia.com...eption/SMPTE DTV Reception Update 2-26-09.pdf

Additionally, note their finding on 2 edge reception, starting on page 25.

The next link further illustrates diffraction (e.g. the ability of a wave to bend around into the shadow formed by an obstruction).

Siting the antenna

The above explains why even antennas located near ground level but aimed (i.e. tilted) toward the top of the obstruction, successfully receive 2 edge signals.
 
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#14
Thanks again serndipity for all that info which I will checkout. I like that idea of tilting the antenna which I have never tried. Currently, my antenna is pointed directly at the bottom of a house located on the top of a ridge about 100 feet away.
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#15
Thanks again serndipity for all that info which I will checkout. I like that idea of tilting the antenna which I have never tried. Currently, my antenna is pointed directly at the bottom of a house located on the top of a ridge about 100 feet away.
--------------------------------------------------

freemarket,

Take a look at my albums here where I have photos of a 'tilt-mount' I fabricated and tried last summer on two different Yagis I also built from scratch. The 'tilt mount' did not help me establish either station I was hunting for (TVFOOL is SO wrong on both of them) but I will try again when the weather moderates because one of the 'problem' channels (KOMO-4/(38) ABC) recently moved their transmitting antenna to the top of their tower and bumped up to 880 kW ERP. Good luck! :thumb:

Jim
 
#16
Thanks Jim -- I found your bracket on project 38 and liked it! Very simple, effective, and easy to fabricate. And, I have some 1/8 inch flat aluminum which should be perfect.
 

scandiskwindows9x

Moderator of DTV Latino
#19
hello :

well maybe also can be some problems by the climatic conditions maybe before you could get the channel that have lost by a tropospheric ducting phenomen but now since is getting closer to spring is not any longer in the area the ducting that made able get the channel.

the fluctuation means that the signal can be get the pilot signal but the data that are carrier that are the video MPEG and audio sent via the pilot is lost during the transport of the signal, that could mean that maybe the data is get but the turner is rejecting the data due to the very bad quality, instead of use reed solomon,trellis encorder etc error corrections systems.for .correct the signal problems via math equations and etc

if were multipath issues you could get pixellation and drops in the channel, but you can not get the channel at all, maybe also they varied the transmission power too,

also can you consider that your coaxial cable is causing too the problem by attenuation problems which is normal the data lost over a long wiring .

well that are my two cents

i have similars issues with channels that gets pixellated or just no signal with an fluctuation of signals wildy.

best regards
Francisco
 
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