wierd reception problem

[kornnutz]

my tvfool report is here:
http://www.tvfool.com/?option=com_wr...da32534a98d153

I have an 91XG on a 25' pole pointed approx 71 deg Magnetic or whatever brings in the strongest signal for my 21.1 channel.
all the channels I am interested in receiving are from the same direction (as far as I can make out)

I can't seem to get a signal for my channel 42.1 which is my CBS

all the channels are listed with positive NM ratios and the 91XG has a 16 DB gain, so I cant figure out why I can't get channel 42. My only thought is that I am pointing directly at a tree,but its trunk is only 6" thick. however, my channel 21 has only 3db signal more than 42 (on the chart), and 21 works fine, so I'm stuck.


I also have a CM3042 before the splitters, but I aim with a laptop and ATSC tuner connected directly to the antenna wire.

I use the signal level reader in Media Center for Windows 7

Any Ideas?

I would also Ultimately like to pick up one of the PBS stations, could i get a recommendation?

also, I know its a long shot, but would 4 91XGs and a phemt pre-amp pull in the ION station thats in my chart?

[kornnutz]

Is my problem the repeater to the south?

[John Candle]

Read and understand this about Real and Virtual digital tv channels. forum.tvfool.com/showthread.php?t=695 . I see 2 WIAT CBS'S at different locations , Tvfool is not 100% accurate , past experience at other posts and locations is one will be an active transmitter and the other will not. . The WIAT at 71 degree magnetic compass is showing the Real channel as UHF 30 and the Virtual channel as UHF 42.1 . . The WIAT at 144 magnetic compass is showing the Real channel as UHF 42.

[John Candle]

You can also go to the >>Start MAPS<< part of tvfool , enter in address city state etc. then enter in the antenna height and select current + pending stations. Then click on the circles next the stations call letters like WIAT.

[Tower Guy]

Originally Posted by kornnutz

I also have a CM3042 before the splitters, but I aim with a laptop and ATSC tuner connected directly to the antenna wire.

Can you pick up CBS with the laptop connected before the distribution amplifier?

How long is the feedline between the antenna and the distribution amplifier?

[kornnutz]

I cant pick up wiat with the laptop. I got it once during a rainstorm (low level reflection?)

I understand real vs virtual, I looked at the wrong number in my question about the repeater.

with NM power in the teens and 16 gain from the antenna, shouldn't all those station be in the green(level wise). I get 3-4 yellow bars for 68.1 and 6.1.

I just swapped cables, but it made no difference.

the feed line is approx. 40'.

maybe I could use another uhf pointing south-southeast? to pick up that wiat at 42uhf and PBS?

[kornnutz]

also, on the 91xg, there is a flat bar riveted to the mast right before the active pickup element, mine may have been bent during shipping, should it be horizontal or bent?

[No static at all]

Originally Posted by kornnutz

also, on the 91xg, there is a flat bar riveted to the mast right before the active pickup element, mine may have been bent during shipping, should it be horizontal or bent?

That shape of that element doesn't seem to make a difference from my experimentation. I always straighten it out though.

Have you tried raising or lowering the antenna a few inches? The antenna may be in a dead spot for RF42 now. You may need to experiment with both height & aim adjustments to see all of the desired stations. Most of my stations are in the same exact direction, but some require aiming off axis due to the large trees in front of the antenna.

Originally Posted by kornnutz

also, I know its a long shot, but would 4 91XGs and a phemt pre-amp pull in the ION station thats in my chart?

The ION station is likely too weak to receive reliably at any reasonable height.

[kornnutz]

I straightened the bar and it seemed to help stabilize the signal slightly, also the horizontal beam of the pickup was off axis from the sight-line, so I straightened that too.

I lowered the antenna a foot and it helped me get solid signal on 6.1,21.1, and 68.1, but 42.1 is still nothing. I may order a second 91xg for giggles and do an over/under config.

I DID swing the antenna around to the south to see if I could hit that other tower, but got nothing.

I'm also considering a DB8 to pick up PBS to my south.

[kornnutz]

well, i wiki'd wiat42 and found this:
On April 5, 2010, the FCC granted WIAT a construction permit for a digital fill-in translator on their pre-analog allotment Channel 42.[16] The translator will serve the Tuscaloosa area.

So I guess they are building a tower and its just not on yet.
think they may have reduced power from their main location?

I'm not concerned with picking it up from 50 miles anymore, it'll come in when they get their repeater online.

I'd still like to pick up a PBS station though, currently, none of them come in.

Any Ideas?

[GroundUrMast]

Originally Posted by No static at all

... Have you tried raising or lowering the antenna a few inches? The antenna may be in a dead spot for RF42 now. You may need to experiment with both height & aim adjustments to see all of the desired stations. Most of my stations are in the same exact direction, but some require aiming off axis due to the large trees in front of the antenna.

Excellent troubleshooting recommendations...

Can you try other locations, 'walk the roof' so to speak?

If you are not seeing any PBS with the 91XG, a DB8 will fair no better.

[kornnutz]

the PBS I was talking about is the only uhf I could possibly pick up, its almost 90 degrees from where the rest of the channels are.

the other PBS are VHF.

[GroundUrMast]

WIIQ - CH19 and WBIQ - CH 39 are both UHF. What VHF PBS option are you referring too?

WBIQ should be fairly easy to see using the 91XG aimed @ 071° Mag. WIIQ should have been seen when you swung around to the south...

Have you ruled out a problem with the integral balun on the 91XG? The earlier trouble shooting suggestions are still valid.

[kornnutz]

according to the wiki, tvfool is in error.
WBIQ dropped back to 10 real after the deadline. I don't know why.

I may not have swung around far enough to get WIIQ, but will try tomorrow.
I'll also have a look at the balun.
what should I look for?

[GroundUrMast]

Originally Posted by kornnutz

according to the wiki, tvfool is in error.
WBIQ dropped back to 10 real after the deadline. I don't know why.

I may not have swung around far enough to get WIIQ, but will try tomorrow.
I'll also have a look at the balun.
what should I look for?

Corrosion, loose connection, broken or cracked F-connector, etc. Without some higher tech ($$$) test gear, substitute an equivalent antenna.

The receiving element and balun are an integrated unit that will not fully disassemble without un-soldering parts (I don't recommend that). But you can remove the screws and open the case for a visual inspection of the printed circuit board and solder joints. On my XG91, there is no core type transformer, just a strip-line on a printed circuit board. Don't try to pry the circuit board out, that will break solder joints or worse.

[kornnutz]

What would a healthy ohm reading be?

could I tie a balun to the input screws and see if I get better signal?

[John Candle]

I agree the Tv transmissions are plenty strong enough to receive. I am also thinking that there is some kind of connection problem. All of us that have doing been doing Tv antenna work for a long time automaticly look inside the coax connectors to see if the outer coax shielding is pushed in to ward the center wire and I have found out more the once that the connection part or equipment that can't be bad is the one that is bad. Many times that coax jumper that looks 100% good , is bad. Or the coax grounding block connections on the inside is bad.

[GroundUrMast]

Originally Posted by kornnutz

What would a healthy ohm reading be?

could I tie a balun to the input screws and see if I get better signal?

I don't see a way to remove the printed circuit board without risk of destroying it. If there is a confirmed problem with the printed circuit board then remove it and try a traditional balun. Based on what I saw inside my balun box, an ohm meter will show virtual 0 ohms from one side of the dipole to the other, and infinite from the center conductor to shield (with no coax connected).

As John Candle is saying, resist the temptation to presume something good, and if you're stuck, consider mentally starting over, assuming nothing.


If there is no trouble with your UHF antenna and WBIQ is on VHF 10, consider adding a high band VHF antenna. Combine the UHF and VHF signals using a UVSJ. A Y5713 or Y10713 come to mind.

[kornnutz]

if the balun was bad, would I get the same performance as a bowtie?
'cause I've tried a bowtie and of course, it only picks up local stations.


and yeah, good point, I troubleshoot computer issues for a living, the same applies.

[GroundUrMast]

Originally Posted by kornnutz

if the balun was bad, would I get the same performance as a bowtie?
'cause I've tried a bowtie and of course, it only picks up local stations.


and yeah, good point, I troubleshoot computer issues for a living, the same applies.

Who knows what a cracked solder connection or some corrosion would behave like... We are dealing with RF in the UHF band, changing the length of a tuned element a few millimeters is significant. Corrosion can turn a connection into old fashioned crystal radio detector... All quite unpredictable.