Mounting Two 8200U On The Same Mast
 

Hello,

I have a Winegard HD8200U mounted on a 10' mast on my roof. Current I am able to receive every LOS and edge channel with the exception of real channels 8 and 10. I receive stations from 2 different markets and they're close to being in opposite directions. I am thinking of getting another HD8200U and mounting it on the same mast. How far apart do the antennas need to be or is there a better option. I do not want to use a rotor because of the DVR.

I have attached my report.

http://www.tvfool.com/?option=com_wr...b97d707e909613

Thanks!

The 8200 is a poor choice for the Lake area as it has all those humongous elements at the back that will do nothing except provide a roost for the birds. There are no low-VHF stations anywhere in Missouri. trying to combine two of them aimed in opposite directions is probably a project left undone.

Aimed at Fordland you ought to be able to pick up KOLR. I see no probability of reliably picking up KOMU or KRCG from Columbia/Jeff City even if aimed at in that direction.

There are large areas of the Lake that are literally "black holes" for reception due to the terrain. Locations where a decent path in both directions are relatively rare. You're probably fortunate to be in one of them!

If you can identify the specific stations in each direction you want, it would be easier to advise you.

I want to get the stations from up north since that is where I'm originally from. I get everything but KOMU. KRCG comes in ok, but if I can't get KOMU I am thinking of aiming toward Fordland and getting a VHF HI antenna to aim at KRCG since KOLR doesn't want to come in for some reason and those are the only choice for CBS.

However, I would like to receive all channels from both markets if possible. I could safely put a 40' mast on the roof.

I've attached the spectrum analysis for KOMU and KRCG. The noise floor is a tad bit higher for KOMU than it is for KRCG. I think that's why I am able to get KRCG and not KOMU. I can get one for KOLR tonight.

Thanks!

I don't recognize that SA display. However, the displayed noise floor is also going to be a function of the resolution bandwidth and detector type if those are available settings.

Are you using any preamplifier?

This is the analyzer:

http://www.tjjinsaixun.com/en/catego...w.asp?newid=56

I borrowed the meter, so I am not too familiar with it. It's been 15 years since I've used one. I wanted to compare the signal strength of the channels I was getting and the channels I wasn't as well as look for interference.

I don't have a preamp, but i do have an HLJS. I had a major spike at 187MHz and figured it was the 2nd harmonic of 93.5's radio station. The HLJS killed the spike. I have ~30 feet of RG6.

I have attached the KOLR analysis

Thanks!

Thanks, never heard of that analyzer. It appears that it can only be found on Alibaba...

I'd run over to Menards in Lake Ozark and see if they have an RCA preamp on hand. it's under $25 and its good enough for testing purposes. If they're out, try the Home Depot and look for a Winegard amp. Neither rank high on my list of favorites, but they're the only ones you will likely find in a retail store at the lake (or almost anywhere else, for that matter).

Do keep the HLSJ in-circuit to fully suppress 93.5.

I have a ChannelMaster 7777. Also, I borrowed two different Winegard preamps to test. I have tested them in many different combinations (ie. FM trap on/off) to no effect.

The tuner will pause for awhile on KOMU when pointed toward Columbia and KOLR when pointed toward Fordland, but will eventually move on without tuning those channels.

Special effort is required to receive weak signals with a negative Noise Margin.

Your tuner is stopping and moving on because the signals have a SNR below 15 dB.

Without a preamp, signals below NM -2 dB with an antenna gain of 12 dB can not be received because of the tuner NF that is added to the thermal noise floor and the minimum required SNR of 15 dB.

With a preamp, the antenna gain must bring the signal SNR up to at least the minimum required SNR plus the preamp NF BEFORE the preamp input, because the preamp NF makes the NM more negative.

http://forum.tvfool.com/attachment.p...1&d=1499692621

http://forum.tvfool.com/attachment.p...9&d=1453496093

Signals with a NM below -15 dB are buried below the thermal noise floor; antenna gain can not "pull them out of the noise."

Fortunately, the tvfool report has poor accuracy with 1 and 2Edge signals, and VHF signals can often diffract over terrain interference and the curvature of the earth to arrive at your antenna.

Yeah, I had a the TV up on the roof with 10 ft of RG6 and still wasn't able to receive KOMU or KOLR. A preamp didn't help because the signal wasn't good enough to begin with. I'm wondering if I need something other than the HD8200U or need to go up higher. I'm not afraid of spending money on this, but I don't want to throw good money at bad by adding/changing an antenna and/or a telescoping mast.

That was a good test.
Yeah, you need the HLSJ. Based on my estimate of your location, KYMK is only 1.5 mi away with aignal power of -6.8 dBm.
http://www.fmfool.com/modeling/tmp/5...3/Radar-FM.png
If there are trees or buildings in the signal path, going higher might help. If not, then run your tvfool report at different heights. Going higher is expensive.

Antennas with more VHF-High gain than the 8200 are hard to find. You could build a wire rhombic.

You need a way to measure your progress, to tell you if more effort and expense are justified. Your SA can give you a rough idea of SNR, even if the tuner doesn't pick up the channel. A SiliconDust HDHR can give you SNR, which they call signal quality. My Sony TV gives SNR as low as 13 dB on the Diagnostics Screen, but only if it has picked up the channel. You could get your system noise figure down to about 1 dB if you use a halfwave coaxial balun and a preamp with a NF of 0.4 dB, but it might be a waste because the ambient local noise above the thermal noise floor is higher on VHF-High than on UHF.


http://forum.tvfool.com/attachment.p...1&d=1489975414

I use my Sadelco DisplayMax 800 to measure the noise floor on an adjacent unused channel for an estimate of SNR.

http://forum.tvfool.com/attachment.p...7&d=1443912401

I can also measure the signal and the noise in an adjacent unused channel on my old Sadelco 719E signal level meter (SLM). I have a VHF-High signal that is just barely above the noise level. A digital signal sounds like white noise if I turn on the audio. The 719E is on the left.

http://forum.tvfool.com/attachment.p...1&d=1440873529

I assume that you have grounded your coax shield with a grounding block connected to the house electrical system ground to reduce the possibility of interference.

KOMU at -18.3 dB NM is 3 dB below the thermal noise floor. KOLR is at the very fringe in a dead zone of the coverage map and blocked by the curvature of the earth. Your location has very rough terrain; small changes in location can make a big difference in the tvfool report. Here is the report based on my estimate of your location near the intersection of Goodfellow Ave and Procter Dr; look at the KOLR NM.
http://www.tvfool.com/?option=com_wr...b97d8f1ff9f5b9

http://forum.tvfool.com/attachment.p...4&d=1451445268

KOLR coverage map:
http://www.rabbitears.info/contour.p...=1324294&map=Y

http://forum.tvfool.com/attachment.p...8&d=1451488366

red spots, weak signal
no red spots, no weak signal

http://forum.tvfool.com/attachment.p...7&d=1451487944

Here is my reports with a 30 foot and 40 foot mast.

30 feet off roof:

http://www.tvfool.com/?option=com_wr...b97de61dce098e

40 feet off roof:

http://www.tvfool.com/?option=com_wr...b97d7a84392a50

From the reports, extending my mast will help a lot. I will probably have to go up at least 15 feet to get over the trees to the north before they leave this coming spring anyway.

I have not grounded the antenna yet as I have not permanently mounted it.

When the HD8200U is pointed 195° I receive 15, 49, 28, 19, 44, and 23. When it is pointed 21° I receive 15, 49, 17, 12, and 20. I have already resigned myself to the fact that I may not be able to receive 8 or 10, but there are channels I can get from both directions that I want to get.

So, back to my original question, :-) if I get something like a Winegard HD7698P and mount it facing 195° and mount the HD8200U facing 21° (or 38° if KOMU will not come in), how far apart do they need to be vertically as to not interfere with each other? Also, how would I connect them together? Should I connect them somehow on the mast, or should I run seperate coax and connect them lower? Is there a totally different and better option I am missing?

Thanks for your time. I really appreciate all of your help.

The basic rule is 1/2 wavelength of the lowest frequency.

http://www.tonercable.com/pdf/antenna.pdf

The 7698 seems to have the same VHF-High gain as the 8200 and is not as wide. so it would be easier to get up higher.
https://mattgadient.com/2011/06/02/w...on-and-review/

Keep them separate for lowest losses. Two antennas, two preamps, two coax feedlines, two connections on the grounding block, two power inserters, then think about ways to combine.

Each antenna should get what you want before combining; it isn't going to get any better after combining.

Trying to combine them with a splitter in reverse isn't a good idea.

1. Separate DVRs
2. One antenna to the TV antenna input, second antenna to DVR and then to TV aux input
3. DVR with more than one tuner
4. SiliconDust HDHR network

An Alternative to Rotators and Antenna Combiners
http://forum.tvfool.com/showthread.php?t=820

A tuner on a good TV usually performs better, in terms of sensitivity and multipath, than a DVR or HDHR tuner. With a marginal signal try the TV tuner first.

You are welcome; glad that we were able to give you some ideas to try. Please let us know the results of your tests on this same thread,

Best regards,
rabbit

That would have been good information to tell us up front.

As noted previously and based on your TVFool data, I cannot reasonably see any reason for optimism that you'll get the two stations from the northeast. KOLR *should* come in, but that's based only on the signal analysis which has a very wide margin for error in situations such as yours.

Your best bet for improvement is antenna elevation, as much as you can manage or afford to invest in an experiment.

Best of luck!

I purchased a Stella Labs 30-2476.

I am able to get KOLR when pointed at 195° and I get KOMU, KRCG and KMIZ when pointed at 29°. I get KMOS and KRBK no matter what.

I left the 30-2476 pointed at 29° and mounted the HD8200U pointed at 195°. I used an HLSJ on the 30-2476 to block FM and connected them with a UVSJ. I was able to get everything except KOLR from the south and I got KOMU and KRCG from the north.

For giggles, I decided to connect the antennas with equal lengths coax and a splitter. I lost KOZK until i connected the CM-7777. Then I got every 2Edge and better except KNLJ and KQFX.

Throughout this 2 months of tinkering, I have been able to receive every 2Edge or better station with good signal. Since my goal is to get all of these channels at once on my DVR, I have drawn up a plan building an "H" shaped mast (similar to the attached picture) to mount antennas to and attach that to a 30' guyed mast on my roof to get above the trees. I have attached a diagram of equipment and how I plan to aim and connect it all together.

Please let me know if you have any ideas, suggestions, criticisms, or just want to tell me to buzz off. :-)

Thanks a million!

Your diagram shows a very ambitious project. You have the right ideas about making sure each antenna gets what you want before combining, about more height, about a HLSJ to block FM, and about a UVSJ to combine UHF and VHF.

But I see a possible problem using a splitter in reverse as a combiner. Sometimes it works, and sometimes not. When the signals from two UHF or two VHF antennas are combined, each antenna can pick up the same signal. When those signals arrive at the combining point they will interfere with each other if they are not in phase, which can cause the loss of channels.

I understand your desire to combine all antennas because of the DVR, but I want you to be aware that there might be a problem. CATV systems use a separate antenna and a single channel amplifier for each channel, and then combine them, which works well, but is very expensive.

There might also be a possible problem with overload. Which 7777 do you have, the old model with separate inputs for VHF and UHF, or the new 7777 with only one antenna input?

rabbit73 mentions inserting and the expense of this.

I hope to dabble in that along with going for some Springfield stations myself. In my case inserting 17 & 22 along with 49 into my main UHF going to KC, and bring along the VHF for 8 & 13 as it is now with the UVSJ.

eBay has a chap selling custom items from Europe. I have not really tested it yet.

http://i878.photobucket.com/albums/a...ps4yd31dsj.jpg

In theory you could insert 17 & 22, I would think KMOS would come through easily on the backside of your UHF.

They might be able to insert 10 into your 8 & 13.

IF this was thought through it MIGHT help eliminate the trouble combining. BUT this is still uncharted territory for me.

My plan is to make sure to use equal lengths of coax through the combining process. If that doesn't work, I plan to adjust the length of the final leg of coax that goes in to the splitter on one of the antenna pairs.

My hope is it will work the first time since it worked in testing. :-}

Has anyone tried this approach?

Thanks!

Ah, yes; that's their new one with more gain than the 2475. It's Stellar, not Stella.
Many people have tried it; sometimes it works, sometimes not. The most recent examples are with the 8-bay antennas with two 4-bays that can be aimed in different directions like the AD DB8e. The marketing departments try to convince you that it will work in all cases; the reality is that it doesn't. It seems to work best when the two panels are at right angles (90 degrees).

Most of the time the combining is done right after the antennas. Your plan is to combine much later which will introduce more phase errors because of the multiple connections before combining.

When you have two identical antennas aimed in the same direction, the signals coming out of the antenna terminals for all channels are in phase. When you connect them to a combiner with equal lengths of coax, they remain in phase for combining, giving you 2.5 dB gain (3 dB - 0.5 dB combiner loss).

When you have two identical antennas aimed in different directions, the signals from the same channel coming out of the antennas are not necessarily in phase or of equal strength, so making the coax lines the same length is no guarantee that the combining will work.

It IS possible to adjust the length of one of the feedlines so that the signals will arrive at the combiner in phase, but that will only be good for that channel because the other channels are on different frequencies and require different lengths. To say it another way, you could end up "chasing your own tail" trying to get them all in phase.

You just have to try it to see if it works; if it doesn't work, you will lose some channels.

You didn't answer my question about which 7777 you have, old with two antenna inputs, or new with only one.

I'd suspect that phasing won't be much of an issue since the F/B ratio of the antennas will pretty much ensure that the very weak signals from the opposite direction will be well attenuated, probably by 10 dB to 20 dB as compared to the desired signals off their intended antenna, and those opposite direction signals will be below the noise floor even after amplification.

Brute force amplification and combining has a decent chance of working in this situation.