Antenna change - does this make sense?

Support & Troubleshooting
1

A channel I was trying to get (22) came in okay, but weak at night. I just put the antenna about 2-1/2’ higher, still aimed in the same direction (270 deg), it’s now coming in better, but I completely lost another channel (13) that I was getting.

The change was to add an extension to the mast, requiring adding a 6’ extension cable to reach the new height. I used a digital compass to assure I was pointing in exactly the same direction as before. Now, channel 13 doesn’t even register when I do a scan with Tablo.

2

Each time you add cable, you are losing part of the signal. If you use a coupler (to connect two cables together), you are also losing signal. Is it possible to change the cable to a single run? Also - make sure it is a good RG6 cable - other cables work, but have higher loss as well.

Also, this time of year (very hot days, with cool nights) will create tropospheric propagation which can cause co-channel interference (a channel from a distant town is interfering with the station). I have this issue in Austin, TX - there are 3 channels that share a frequency with stations in Houston (almost 200 miles away) and/or San Antonio (about 120 miles away), and during these atmospheric conditions, the channels go from great signal to “no signal”, usually around 11:00PM - 9:00AM. Once it heats back up, the channels are fine.

3

Yeah, the heat hit here and the channel is back. Frustrating.

The antenna has a built-in preamp. Could adding a preamp help boost the signal? I have about 60’ of cable now, with two couplers. I know I can’t do single run, code requires a grounding block before the cable enters the house, so no matter what I will have at least one coupler.

4

You need to determine if it is a problem with the cabling, the preamp, or tropospheric propagation. If it is tropospheric propagation, there is literally nothing you can do to stop it. Digital TV signals are basically “1” and “0”, and if you have another channel on the same frequency, they cancel each other out. In the old analog days, you would see two pictures on the screen at one time.

Since it works fine during the day, I would bet it is tropospheric propagation.

Can you run a rabbit ears report and share the link? https://www.rabbitears.info/searchmap.php

From that report, I can see the channels (RF channels specifically), and see more information about the signals.

5

Sure, but the map doesn’t tell the whole story.

https://www.rabbitears.info/searchmap.php?request=result&study_id=124491

My antenna is aimed at 270 deg, I get excellent reception on 19- and 21- channels, the hard channel is 13- which is on the VHF-lo band. Everything (except the 13-) comes in perfectly, even though the report says poor.

Talking with others here when I was first setting things up, I was given the impression that a 50’ run shouldn’t be a problem, and it wasn’t, I just needed to get the antenna higher to get the 13- and 22- channels; I did that and it brought in the 13- series fine, the 22-series was okay, but faded at night. Today I raised it an additional 2.5’ to try and get the 22-series, it did that but lost the 13-series until, as you said, things heated up, now the 13-series is back, but not sure for how long.

6

For VHF-low, usually you need an antenna specifically designed to pickup VHF-Low frequencies. The signals also indicate “fair” signal reception for quite a few of the stations (which means they are likely to have episodes of pixelation at some point). The ones that say, “Poor” and “Bad” you can forget about.

What brand/model of antenna are you using, and how high up is it (approx)?

7

I swear things changed for many channels during the FCC repack. I installed 2 very good Televes long range uhf/vhf antennas about 3.5 years ago and at the time my reception was awesome. Every channel had a good signal and several were regularly 100% on my TV’s signal meter. Now some of my channels that used to be strong, have become hit or miss on a regular basis. And none of them give me 100% anymore. I know the summer months can wreak havoc on TV signals but it has become unusually frustrating this year. I’ve played around a bit with my antennas but nothing helps.

Tonight I has waiting for a certain Star Trek Voyager episode to play on H&I so I could complete my Tablo ripped collection. The signal on that channel tonight was zero. Grrrrr. On good days that channel is strong. It will take months for that episode to play again.

1 Like
8

Yeah, the FCC has been a b–ch, that’s the two channels I’ve been having problems with. I’m in a valley, which doesn’t help. That’s why I thought an additional 2-1/2’ would make things better. I still don’t understand why it’s worse.

9

I have the Antop Big Boy (UHF/VHF) AT-400BV antenna. The height is ~22.5 ft (was 22 ft).

I don’t go with the signal ratings, reason is that the ones marked fair, for the most part, come in great, the one marked good doesn’t come in at all, never even heard of the station. Other scans I did from other websites disagree with rabbitears ratings, personally I think it’s a crapshoot.

The antenna has a pre-amp and a power booster, so I don’t think two couplers would make a big difference, even 60’ of cabling shouldn’t matter all that much. But, I’m a newbie to this, so what do I know (serious, not sarcastic)?

10

Do you have the preamp set to low or high power? I have the same antenna and at my location, I found that I received the best signal to noise ratio and signal strength at the low setting. It is possible to overdrive the Tablo’s tuners if your signal is too strong.
My Samsung TV has a good signal strength and SNR meter, so with the antenna connected to the TV, I checked all the channels I could receive with both the low and high setting on the preamp. I found that my best overall viewing was with the preamp in the low setting.
I still occasionally have reception problems, primarily due to atmospheric conditions or aircraft, but overall great reception.

12

My understanding, right or wrong, is that the repack was to enable frequencies for 5G cellphone. We have fallen far behind Europe (and even China) on broadcasting, mainly because our frequency setups are a mess. Instead of just repacking to low-VHF they need to totally revamp our frequency assignments.

13

Mine doesn’t have high or low, it has on or off. Off is worse.

What I am getting now is “signal strength is too weak” on the 19- series. 13- sometimes comes in, other times it is “too weak”.

Like I said, and I don’t understand it, when it was lower I got better reception. I don’t know if it is because of the extra 6-ft cable or not. The extra is a type-6 cable, the rest is the cable that came with the antenna, it’s not marked so I don’t know what type it is.

14

When troubleshooting antenna setups, the first thing I do is hook up the antenna directly to a TV on a short cable, and do a channel scan. Then you can look at adding in splitters, pre-amps, longer cables, etc. I always scan in the afternoon or early evening (before 7:00PM) as there is less chance of problems with tropospheric propagation.

The antenna you have is designed to work with the pre-amp, so you might want to try it with a shorter cable for testing as well. The “magnetic” and “true” directions aren’t always 100% accurate, sometimes it takes “fine tuning” by moving the antenna 3-5 degrees and trying a rescan.

Once is it setup with good reception with only the short cable, then try the additional cabling in the home. There are a lot of possible problems in multiple lengths of cable, couplers, splitters, etc…and if you eliminate all of them, it makes it easy to troubleshoot (simplest circuit = best way to diagnose).

1 Like
15

On is high, off is low and removing the power inserter completely is no preamp. The cable that came with the antenna is RG6 according to the manufacturer.

@ronintexas is correct about eliminating your possible problems to determine if you have a bad cable, coupler, splitter, etc.

16

Yeah, but how do you do it with a short cable…put the TV on the roof?

17

I have a 25’ RG6 cable that I hook directly to the antenna, and run it down to a 24" TV. Not really “portable”, but cheaper than a $500 diagnostic unit to test the install. It still stinks running up and down the ladder…

18

Hi tecumsa,

You’re spot on to realize that it’s because your PBS WQED is now on VHF-lo that you’re having problems. They moved down frequencies in July 2019, because of the repack.

But, they knowingly did so. I see your mention about it being the FCC doing this to them, and SophieCat mentioned it, too. Realize though that WQED was the only TV station in the nation that during the 2017 auction took money to move from VHF-Hi to VHF-Lo. Had they not accepted the proceeds, they would have either remained within the VHF-Hi range (RF7-13), or possibly even moved up to UHF (where smaller home antennas work). They were happy to receive money equivalent to their annual budget, per this article I Googled up: https://www.post-gazette.com/ae/tv-radio/2017/09/28/Embattled-WQED-station-bolsters-fund-through-auction/stories/201709280254

Like ronintexas noted, You need an antenna that is expected to receive VHF-Lo. The Antop’s VHF dipoles out each side don’t have a long enough wingspan, unfortunately.

I like to refer to this chart I found on RFCAFE a couple of years ago when thinking about wingspan needs:

To give full credit, it’s from this article: https://www.rfcafe.com/references/radio-news/yagi-antenna-radio-television-news-october-1952.htm

Since WQED is now transmitting on the frequency that historically was Channel 4, the primary dipole element needs to be almost 7 feet across (82 inches…so 2 inches shy of 7 feet) for optimal results.

I’m guessing that if you measured the Antop’s wingspan, it’s a yard or less. Fine for VHF-Hi (Channels 7-13, from the chart), but not ideal for any VHF-Lo. Then your happening to be down in what’s apparently a step-sided valley exacerbates things.

So what to do? One person that posted over in the Pittsburgh thread of AVSForum (I can provide the link if you’re not familiar with that site) had a different antenna than you, but successfully extended the dipole with metal tubing or rod–and scored rather reliable reception of WQED.

Otherwise, you’ll need to add a separate antenna, or replace what you’re using.

I’m afraid the smallest Winegards that have long dipoles won’t be enough. Rather, these come to mind for me–and save you from going to the monsterously long Winegard HD8200:

RCA ANT3036
RCA ANT3037 (with VHF-Lo extensions installed)

Per what last was known, both these RCAs were being manufactured by Winegard. Their main boom is 5-6 feet long, with the widest dipoles 9 or so feet wide.

Channel Master Advantage 60 (model number CM-3018)–Notice this isn’t from their “Digital Advantage” product line, since those aren’t wide enough for VHF-Lo. I’d also be a bit concerned that their Advantage 45 (CM-3016) wouldn’t be quite enough for you in the valley.

Amazon also lists a VHF-Lo-only antenna if you dig far enough. But there’s so few reviews and it comes from overseas that I’m unsure about even mentioning it–plus it costs in the same range as the above options.

I don’t have any VHF-Lo broadcasts in my market. But I do use an RCA ANT3037 (without the extensions installed) for my VHF-Hi reception. Lowes was closing them out from their store inventory a couple of years ago–but Home Depot will ship-to-store free I’m finding.

If you want to add one of the above, you could leave your current Antop as is, put one of these on the same mast, run a separate coax down to where you have the power injector for the Antop, then add in the VHF-Lo coax line with a “High Low Signal Joiner” (HLSJ for short): https://www.amazon.com/SEPARATOR-JOINER-HIGH-FREQUENCY-CABLETRONIX/dp/B01LYNXRXH
The key is that the HLSJ would need to be placed so as to not divert the current going to the Antop from the power injector.

Lots said here. Hopefully not too overwhelming. ~~ Cheers! Statmanmi

1 Like
19

I went to RCA’s website and used their antenna finder, while it returned the stations in the area it didn’t recommend any antennas.

I’m going to give a try replacing the cable with a shorter run, only one coupling, like ronintexas suggested. Failing that, I’ll give lowering the antenna a little at a time. I was able to pull in 13- and 19- with the antenna at 20’, 19- just wasn’t strong enough to schedule recordings an be comfortable they would come in. 13- was nice and strong 90% of the time. That’s why I tried raising it 2-1/2 ft, thinking the additional height would bring in a stronger signal. Maybe, like ronintexas said, the additional 6’ of cable and an additional splitter was enough to drop the signals.

Heat here won’t break until Wed., so might hold off until then, don’t like going up on the roof with heat in the 90’s and humidity in the 60-80% range. We’ll see.

20

Okay, does this make any sense?

I can’t undo the existing cables because they run through the attic and down between the joists, so, instead, I move the Tablo to a different location, near the antenna. I don’t have another RG6 cable, so I used a 25’ length of RG19U, this cuts the run by 36’ and eliminates one coupler. Prior to making the changes I scanned the Tablo and I am picking up the 13- and 19- channels, after making the changes I lost the 13- and 19- channels. So, I moved everything back and now I have the 13- and 19- channels back. I would have thought, even with the RG19, that the shorter run would have worked.

They’re not reliable, a recording I had set up for last night didn’t occur because of poor signal.

21

Were you able to tune the channels on a TV or other devices during the same time?

You have two variables - first is the Tablo, second is the reception.

Contact support, and have them look at the logs. I have two different 4-tuner Tablos, one in operation for 3 years, one in operation for over a year. Rarely are there issues with recordings, playback or other problems with the Tablo.