Add 2nd antenna or a rotor?

PCoaster · 8-Feb-2018, 3:23 PM

I have a DB8e on a mast - elevated 7 feet above lower roof line - clear line of sight, I have a Juice Amp I point mostly to the Orlando towers.

I get most of the channels I want with the exception of CBS and NBC, these are either great (when they come in) or nothing at all. My question is should I use an antenna rotor to change direction when I want to get to CBS and NBC, since my other channels are just fine currently. I was warned in an earlier post that adding a second antenna can be tricky with signal interference, so I am not sure which way to go.

I appreciate any advice, and specific product recommendations (rotor,antenna)

My analysis: http://www.tvfool.com/?option=com_wr...9038a14234f9fd

ADTech · 8-Feb-2018, 5:17 PM

Quote:

these are either great (when they come in) or nothing at all.

That is the nature of digital signals, they're either perfect (enough) or they're not. The transition is VERY abrupt and is referred to as the "digital cliff effect".

You have two separate issues, most likely. I'll cover them separately.

Some history: All of the major Orlando stations have their primary transmitters located just outside Bithlo. All of the major Orlando stations, except WESH, went with UHF channels back in the original digital transition in 2009. WESH, on the contrary and unfortunately (for their antenna using viewers), chose to be the odd man out and chose VHF 11. In an effort to mitigate the issue, they eventually added local UHF translators in the Deltona (UHF 18) and Orange City (UHF 24) areas.

Okay, need a few more details.

1. When you do pick up WESH ("NBC"), are you picking up the channel 18 Deltona translator or the VHF 11 primary signal? You may need to see if your TV set has a diagnostics screen that identifies either the RF frequency or the "real" channel number. Both will display the received channel as 2.x so that won't help.

2. What direction do you have to adjust the DB8e to in order to pick up your NBC broadcast?

3. Do you have the DB8e's panels in parallel or are they splayed using the included adjustable swiveling feature?

4. Re: CBS. If you have the DB8e's panels in the basic parallel configuration and if the DB8e is aimed directly at Bithlo but WKMG won't come but, if the antenna is aimed elsewhere (which direction?) and comes in, then you likely have a signal path blockage (usually trees or buildings out in front of the antenna) and you need to consider moving the antenna, if feasible, to get the antenna out from behind the obstacle. Even if there is no visible obstruction, you may still need to relocate the DB8e and try again as you may have found a near-dead spot by accident. Just don't drill any new holes yet...

PCoaster · 9-Feb-2018, 5:17 PM

Okay, need a few more details.

1. When you do pick up WESH ("NBC"), are you picking up the channel 18 Deltona translator or the VHF 11 primary signal? You may need to see if your TV set has a diagnostics screen that identifies either the RF frequency or the "real" channel number. Both will display the received channel as 2.x so that won't help.
Answer: The TV channel is 2.1, no ability determine the exact frequency I am getting.

2. What direction do you have to adjust the DB8e to in order to pick up your NBC broadcast?
Answer: the smallest movement seems to help when I take the mast a bit towards the 150 mark of the compass

3. Do you have the DB8e's panels in parallel or are they splayed using the included adjustable swiveling feature?
Answer: I have them in parallel (side by side no tilting in opposite directions)
Pic Here https://drive.google.com/open?id=132...9y9K2_K7LhMKYT

4. Re: CBS. If you have the DB8e's panels in the basic parallel configuration and if the DB8e is aimed directly at Bithlo but WKMG won't come but, if the antenna is aimed elsewhere (which direction?) and comes in, then you likely have a signal path blockage (usually trees or buildings out in front of the antenna) and you need to consider moving the antenna, if feasible, to get the antenna out from behind the obstacle. Even if there is no visible obstruction, you may still need to relocate the DB8e and try again as you may have found a near-dead spot by accident. Just don't drill any new holes yet...

Answer: I uploaded a pic of the antenna, also the compass settings (rough idea using iPhone compass). I have the antenna mast cemented in so no relocating, but willing to add a rotor, adjust as needed,
etc.

Pic Here:
https://drive.google.com/open?id=1lh...tjKuEC70-bPVrd

Thanks for your time and advice!

ADTech · 9-Feb-2018, 7:00 PM

You'd probably get the most cost-effective results if you were to add at least 5' to your mast so the antenna cleanly misses your neighbor's rooftop with a couple of feet to spare. As it is now, that roof is probably in your Fresnel zone and is effectively blocking too much of your RF signal path which then requires you to have to mis-aim the antenna to pick up a signal from off-axis.

I have little confidence in smartphone apps for use as a compass. I usually joke that they're accurate to only +/- 180°. It's far more practical to use the interactive maps feature here, turn on the signal path lines, and then drag and drop the marker onto the antenna mounting location in the satellite (not the 3D view, if it pops up when you zoom in)view. The greenlines give you a clear visual reference as to where the signal path lies.

Your indicated signal path to Bithlo is 170° true, to the WESH translator is 187° true. You're mis-aimed by up to 30-40° at 150° which suggests that either you may have one of the sidelobes instead of the primary reception lobe of the antenna facing south or, as mentioned above, the signal is getting blocked by the neighbor's roof. At over 60 miles out, there is no margin for errors or omissions, you have to do everything right.

jrgagne99 · 9-Feb-2018, 7:09 PM

Quote:

Originally Posted by PCoaster

1. When you do pick up WESH ("NBC"), are you picking up the channel 18 Deltona translator or the VHF 11 primary signal? You may need to see if your TV set has a diagnostics screen that identifies either the RF frequency or the "real" channel number. Both will display the received channel as 2.x so that won't help.
Answer: The TV channel is 2.1, no ability determine the exact frequency I am getting.

Are you sure there isn't a diagnostic screen option for your TV so you can see exactly which real channel you're receiving? What is the TV make/model, maybe we can help you find it.

rickbb · 9-Feb-2018, 7:25 PM

A real compass is cheap, even one that can be adjusted to read "true" north instead of magnetic. I recommend getting one.

I vote for a aiming or blockage issue, that 8 bay is one of, if not the, highest gain antennas on the market. You shouldn't be having this problem.

Also one of your NBC stations is VHF, you could get that one with by adding a VHF only antenna and using a joiner to keep UHF on the 8 bay and VHF on the other. Wouldn't help on the CBS though.

Edit; Ok went and looked again, somethings off on that report. It lists WESH twice, one at real channel 18 and again on real channel 11, both at 2.1 virtual. Wonder which one is legit?

ADTech · 9-Feb-2018, 8:19 PM

Quote:

It lists WESH twice, one at real channel 18 and again on real channel 11, both at 2.1 virtual. Wonder which one is legit?

Both are, see post #2. I'm operating under the belief that the channel 18 translator should be receivable with the DB8e due to the provided plot so I didn't bring up the VHF 11 angle as being in need of a solution.

PCoaster · 9-Feb-2018, 9:25 PM

Thanks so much for the detailed information, do you think a different antenna would help along with the higher mast?

PCoaster · 9-Feb-2018, 9:33 PM

My Tv is a Samsung 65" Model: UN65KS8000FXZA

I just got deep into the settings and see that my NBC Channel 2.1 is actually Channel 18 with a SNR of 0-12 DB and a modulation of 8 VSB. I don't know what that all means, but it sounds like you guys do! The channel is NOT coming in right now so those numbers reflect that, suggestions now?

rabbit73 · 9-Feb-2018, 10:56 PM

Quote:

do you think a different antenna would help along with the higher mast?

You already have the best antenna for 18.

Quote:

I just got deep into the settings and see that my NBC Channel 2.1 is actually Channel 18 with a SNR of 0-12 DB and a modulation of 8 VSB.

Good work. The important number is the SNR; it must be more than 15 dB for reception. Your DB8e antenna is designed to receive real channel 18, which is listed as strong on your report.

My guess is that something is blocking the signals on their way to your antenna, like trees or a roof (as ADTech said).

Another possibility is electrical interference, perhaps from a solar power system inverter.

Is you coax grounded with a grounding block connected to your house electrical system ground?

I would like to look at the satellite view of your location. Would it be possible for you to give me your address and coordinates of your antenna in a PM?

rabbit73 · 11-Feb-2018, 1:24 AM

Thank you for the additional information about your location. I looked at the satellite view and WESH 18 does seem to clear your neighbor's roof, but there are trees beyond his house that look like they are in the signal path. Trees block TV signals:
http://www.hdtvprimer.com/antennas/siting.html
scroll down to Trees and UHF

WESH has three transmitters:
https://rabbitears.info//market.php?...&callsign=WESH

The WESH transmitter on RF channel 18 is considered a DRT (Digital Replacement Translator) that is running only 10 kW, which is not a lot of power for UHF.
https://rabbitears.info/tvq.php?requ...ms&facid=25738

But, it has a very directional antenna that sends only 1 kW ERP in your direction:
http://www.tvfool.com/?option=com_wr...dALLTV%26n%3d3

I think the TVFool report is a little too optimistic about WESH on RF 18. The FCC Longley-Rice coverage map shows your location outside the red contour for WESH 18 because of its low power and directional antenna that favors the SE:

Link to that map:
https://rabbitears.info/contour.php?...a&site=2&map=Y

The coverage map for WESH 11 shows your location inside the contour:

Link to that map:
https://rabbitears.info/contour.php?...a&site=1&map=Y

If raising and/or moving the antenna doesn't help with WESH, I suggest you add a VHF-High antenna to your DB8e to try for WESH on RF 11. The VHF antenna can be combined with the DB8e using a UVSJ UHF/VHF combiner with no interference.

VHF-High antenna:
Stellar Labs 30-2475:
http://www.newark.com/stellar-labs/3...vhf/dp/48Y8141

its big brother 30-2476:
http://www.newark.com/stellar-labs/3...vhf/dp/71Y5462

UHF/VHF combiner between the antennas and the preamp input:
https://www.antennasdirect.com/store...Combiners.html

It looks like this inside the enclosure:

PCoaster · 11-Feb-2018, 4:42 PM

Wow, that is some very good and detailed information, I greatly appreciate it!

Follow Up Questions:

1. If I add the additional antenna I guess I would place it at the top, the DB8e already has a joiner for the two sections, I guess I would take the cable coming out of that joiner and put it into the "VHF In" of the combiner you provided a link to. The new UHF antenna plugs into the other port and the center port is to the TV, correct?

2. Will the suggested UHF antenna be used to only get the NBC channel (RF 11) or is there hope to get additional channels or perhaps improve others I already get?

3. Based on the direction I have the DB8e aimed currently, which way would the second antenna need to be aimed to get NBC channel (RF 11) ?

4. Of the two recommended UHF antennas...is the smaller one enough to reach what I am aiming for?

Any other suggestions are welcome.

rabbit73 · 11-Feb-2018, 6:31 PM

Quote:

Originally Posted by PCoaster

Wow, that is some very good and detailed information, I greatly appreciate it!

Thank you; I keep trying and learning more.

Quote:

1. If I add the additional antenna I guess I would place it at the top, the DB8e already has a joiner for the two sections, I guess I would take the cable coming out of that joiner and put it into the "VHF In" of the combiner you provided a link to. The new UHF antenna plugs into the other port and the center port is to the TV, correct?

Um, you are close, but not exactly.

It is the real channel number that determines what antenna is needed.

VHF-Low, real channels 2-6
VHF-High, real channels 7-13
UHF, real channels 14-51

The virtual channel number (like 5.1) is a holdover from the analog TV days to maintain the identity of the station, and is what the TV displays.

Code:


   DB8e >
   UHF   \  U
         UVSJ > preamp > coax > grounding > power > TV
         /  V                     block    inserter
30-2475 >  
VHF ANT

The DB8e is a UHF antenna, so its combiner connects to the UHF input of the Antennas Direct UHF/VHF combiner. The new Stellar Labs antenna is a VHF antenna if you decide to try for channel 11, but only if you can't get WESH on 18. It connects to the VHF input of the UHF/VHF combiner. The center output port connects to the input of the Juice preamp.

Quote:

2. Will the suggested UHF antenna be used to only get the NBC channel (RF 11) or is there hope to get additional channels or perhaps improve others I already get?

The suggested new antenna is a VHF antenna for VHF-High real channels 7-13. It is capable of receiving other VHF-High channels if they are strong enough, but it will not receive any UHF channels because the UVSJ VHF input port will block any UHF channels received by that antenna.

Quote:

3. Based on the direction I have the DB8e aimed currently, which way would the second antenna need to be aimed to get NBC channel (RF 11)?

The Stellar Labs VHF antenna should be aimed at 170 degrees true/176 degrees magnetic, which is a different azimuth than for UHF WESH 18.

Quote:

4. Of the two recommended UHF antennas...is the smaller one enough to reach what I am aiming for?

The two recommended Stellar Labs antennas are for VHF. If your report is accurate, the smaller one should be sufficient with the preamp, but I can't give you a guarantee.

Do I have your permission to show any of the green line images that I sent to you in a PM?

rabbit73 · 13-Feb-2018, 2:26 AM

Thank you for your permission. It doesn't look like your neighbor's roof blocks the signals, but the trees might affect both directions from the south: