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#372339 - 17/10/2019 02:53 Coax question
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12318
Loc: Sterling, VA
So I'm currently attempting to cut the cord. As part of that, I'm trying to set up an antenna, attach it to an HDHomeRun tuner, and record from it using my Synology running Plex as a DVR.

Well, it's been ages since I've dealt with OTA signals and reception issues.

I've found a place in my home where the antenna won't look ugly and where I can get an ok signal. It's definitely on the edge but I get the big 4 and PBS, which is pretty much all we wanted. I found this positioning using the coax cable that came with the ANTOP brand antenna (model AT-400BV).

This evening I decided to install the coax permanently, but I need a little more length so I used my own cable that I use for work. It's a quad-shield RG6 cable, and seems higher quality than the 40' cable that came with the antenna. I'd estimate that I ran about 60' of my cable.

But I've lost channels.

Not all of them, but when I connect my cable I'm getting about half the channels I did before. When I switch back to the included cable, I get those channels back. What gives? My coax isn't running past any power cables, so interference shouldn't be a problem. And it's quad-shield anyway so that should mitigate that. The antenna comes with a required in-line amplifier which I've been attaching to both lines in my tests.

So what's going on here? Is my cable bad somehow? What should I do?
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Matt

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#372340 - 17/10/2019 03:47 Re: Coax question [Re: Dignan]
K447
old hand

Registered: 29/05/2002
Posts: 797
Loc: near Toronto, Ontario, Canada
Where are you installing the inline coax amplifier? Near the antenna end?

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#372341 - 17/10/2019 04:33 Re: Coax question [Re: K447]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12318
Loc: Sterling, VA
Originally Posted By: K447
Where are you installing the inline coax amplifier? Near the antenna end?

On both cables I was putting at the tuner end because that's what the instructions said. I just tried putting it at the antenna end because that will be possible in the location where the antenna will be. I pretty much got all those channels back again so that's pretty great. The reliability is still not as good as it was when the amplifier was by the tuner on the included coax, so I'm a little puzzled and I'm also concerned about this coax that I've already placed in people's homes... Probably going to look at a different manufacturer...
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Matt

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#372342 - 17/10/2019 07:29 Re: Coax question [Re: Dignan]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31563
Loc: Seattle, WA
_________________________
Tony Fabris

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#372343 - 17/10/2019 08:30 Re: Coax question [Re: Dignan]
Roger
carpal tunnel

Registered: 18/01/2000
Posts: 5680
Loc: London, UK
Originally Posted By: Dignan
running Plex as a DVR.


Ditch Plex. Use Emby.
_________________________
-- roger

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#372344 - 17/10/2019 13:57 Re: Coax question [Re: Dignan]
mlord
carpal tunnel

Registered: 29/08/2000
Posts: 14472
Loc: Canada
Originally Posted By: Dignan
This evening I decided to install the coax permanently, but I need a little more length so I used my own cable that I use for work. It's a quad-shield RG6 cable, and seems higher quality than the 40' cable that came with the antenna. I'd estimate that I ran about 60' of my cable.

But I've lost channels.

The antenna comes with a required in-line amplifier which I've been attaching to both lines in my tests.

So what's going on here? Is my cable bad somehow? What should I do?


The 60' feet of RG6 is losing you between 4dB and 5dB of signal: more than half of the original signal is being lost (every 3dB lost is a halving of the signal).

Now the inline amplifier you have, should be mounted at the ANTENNA end of that coax. If you haven't already put it there, do so now and test again.

But most likely the in-line amp is hurting rather than helping. Freebie amps tend to have very VERY high "noise figures", in the 5dB to 7dB range. So that by itself is costing more than half the signal

The rule of thumb for signal amplifiers, is that all that matters in most situations is the noise figure of the very first transistor in the chain. So if your HDHomeRun tuner has, say, a noise figure of 2dB (very likely) on it's internal preamplifier, then anything worse than that in the chain is hurting rather than helping.

I tell my friends to look for an inline pre-amp with a noise figure (NF) under 2dB, or preferably under 1dB. The preamps I use here have a 0.4dB NF. That brand/model is no longer on the market, but several people have acquired ones from http://kitztech.com/ on my recommendation and those seem to work almost as well.

Also, try and minimize coax length and the number of connectors between the pre-amp and the antenna (try for under 3 feet). Because that's the area which the pre-amp cannot help with. Each connector is costing you up to 1dB of signal. Once the signal gets to a (good) pre-amp, the rest of the coax and connectors won't matter.

Cheers

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#372345 - 17/10/2019 14:37 Re: Coax question [Re: mlord]
Roger
carpal tunnel

Registered: 18/01/2000
Posts: 5680
Loc: London, UK
Originally Posted By: mlord
Now the inline amplifier you have, should be mounted at the ANTENNA end of that coax.


Put the HDHomeRun at the antenna end and run 60ft of CAT5. At that point it's digital, and you can ignore losses due to noise.
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-- roger

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#372346 - 17/10/2019 17:22 Re: Coax question [Re: Roger]
mlord
carpal tunnel

Registered: 29/08/2000
Posts: 14472
Loc: Canada
Originally Posted By: Roger
Originally Posted By: mlord
Now the inline amplifier you have, should be mounted at the ANTENNA end of that coax.


Put the HDHomeRun at the antenna end and run 60ft of CAT5. At that point it's digital, and you can ignore losses due to noise.


Yup, great advice for an all-indoor setup. And remove the inline pre-amp entirely if doing that way, unless the pre-amp has a lower noise figure than the HDHR.

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#372350 - 17/10/2019 19:42 Re: Coax question [Re: Dignan]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12318
Loc: Sterling, VA
Thanks, everyone!

Before I turned in last night I tried putting the amplifier on the antenna end and it definitely made a big difference. I got all the channels I wanted, though a couple are a little wonky. They work for recordings, though, where the pauses get evened out.

So just now I removed the amp entirely and while I seem to get fewer of those fringe signals I also seem to be getting a more reliable signal from the channels I wanted.

But your suggestion to put the HDHomeRun on the antenna end is a fantastic one. That thought crossed my mind briefly but I don't know why I ignored it. I think it might be out of concern for the affect of temperature swings on the HDHomeRun. The antenna is on the inside of my garage, facing the outside wall like it's the class dunce. I'll probably make a little shelf for it since the mounting hardware is on the wrong side now, and affix the HDHomeRun somewhere around that. Good idea on that part. I shouldn't have much drop in signal then!
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Matt

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#372352 - 17/10/2019 22:48 Re: Coax question [Re: Dignan]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31563
Loc: Seattle, WA
Use caution when placing high tech electronics into non-climate-controlled spaces such as attics and garages.

I once set up a building-to-building wireless LAN extension, back in the days before Wifi was a thing, this was pre-802.11. I think it might have been Proxim gear, in the early 90's. Bigass directional antennas on each building's roof, with coax cables running from the antennas down into each buildings' attic, where I put the wireless routers and plugged them into the LAN. The idea was the same as the one in this thread: short coax run to the hardware for good air signal from the antenna, then I can run any CAT5 length to anywhere from there. Also, this was specialized coax for those antennas, not just RG6 or RG59, so I don't know if I could have run longer coax even if I wanted to.

I set it up in the fall (sound familiar?) and everything was fine. Then, several months later, the users in the other building began complaining about hard-to-trace intermittent connectivity issues. The weird thing was that they would start to get the connectivity problems at the same time of day, which was mid-to-late afternoon each day. Each morning when I would investigate yesterday's reported problem, everything was fine and not reproducible.

It was of course, caused by the onset of summer weather, with the afternoon sun heating up the attic of one of the buildings. It was well over 100 degrees F in there, and the router was just cooking.

I managed to stretch the coax cable a hair farther, moved the router just a bit lower, into the drop-ceiling area of the office just beneath the attic. Problem solved.
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Tony Fabris

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#372355 - 18/10/2019 01:58 Re: Coax question [Re: Dignan]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12318
Loc: Sterling, VA
Lol those real world physics issues are always fun IT stories.

In this case yes, I'll need to be careful about the weather, but at least I've now run two different lines into my home. One coax and one ethernet, and if the HDHomeRun doesn't like being in the garage then I'll move it back inside. I had it working in both locations. We'll see how it does on ethernet. I have it hooked up now but weirdly I'm not getting ABC now, and the other networks come through strong. Odd. I'll do some more channel scans and see if I can pick it up, but it's not like I watch much on that network anyway.
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Matt

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#372356 - 18/10/2019 02:07 Re: Coax question [Re: Roger]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12318
Loc: Sterling, VA
Originally Posted By: Roger
Originally Posted By: Dignan
running Plex as a DVR.

Ditch Plex. Use Emby.

I'll definitely take a look! I'm month to month with my Plex Pass for now, but I'm not wedded to it and there's some really annoying and clunky UI things about it. The comparison is unfair but it's going to be difficult to go from Tivo to anything else, even with the annoying changes they've made to their UI too.

But yes, I'll give Emby a try. Anyone else have recommendations? Basically it just has to support Apple TV and be able to use a Synology as a DVR. One thing I've been playing with and like about Plex is the automatic commercial removal, which so far has worked pretty darn well...

Side note: what is it with streaming media and "Big Buck Bunny?" It's like the defacto sample video for some reason. I know I've seen it on another box I tried, which is making me wonder: is Emby the grandchild of Boxee?
_________________________
Matt

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#372359 - 18/10/2019 13:10 Re: Coax question [Re: Dignan]
K447
old hand

Registered: 29/05/2002
Posts: 797
Loc: near Toronto, Ontario, Canada
Originally Posted By: Dignan

.... The antenna is on the inside of my garage, facing the outside wall ...
Why so low?

Generally speaking antenna for receiving distant signals prefer to be up high, where there are less obstructions in the signal path.

The materials of the garage wall will also reduce signal strength. How much depends on the materials and the antenna orientation. Glass may provide the least signal reduction, if it is simple glass, not metallic film coated or whatever.

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#372362 - 18/10/2019 14:55 Re: Coax question [Re: K447]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12318
Loc: Sterling, VA
Originally Posted By: K447
Originally Posted By: Dignan

.... The antenna is on the inside of my garage, facing the outside wall ...
Why so low?

Wife

wink
_________________________
Matt

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#372364 - 19/10/2019 00:16 Re: Coax question [Re: Dignan]
K447
old hand

Registered: 29/05/2002
Posts: 797
Loc: near Toronto, Ontario, Canada
Originally Posted By: Dignan
Originally Posted By: K447
Originally Posted By: Dignan

.... The antenna is on the inside of my garage, facing the outside wall ...
Why so low?

Wife

wink
Make a tidy ‘box’ with some art or nice photo on the front/sides, then hang/put the box where the antenna will work better.

Functional art wink

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#372374 - 20/10/2019 19:45 Re: Coax question [Re: K447]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12318
Loc: Sterling, VA
Originally Posted By: K447
Originally Posted By: Dignan
Originally Posted By: K447
Originally Posted By: Dignan

.... The antenna is on the inside of my garage, facing the outside wall ...
Why so low?

Wife

wink
Make a tidy ‘box’ with some art or nice photo on the front/sides, then hang/put the box where the antenna will work better.

Functional art wink

I'm pretty sure that if we hung art on the outside of our house we'd look like nutcases.

the front corner of our garage is the best location on the structure for the antenna, based on the direction of the broadcast towers. There's not really any "up" to go, as the roof is sloped and the rest of the house is behind it, so the further up you go the more you're behind our house and our neighbor's house.
_________________________
Matt

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#372376 - 21/10/2019 01:55 Re: Coax question [Re: Dignan]
K447
old hand

Registered: 29/05/2002
Posts: 797
Loc: near Toronto, Ontario, Canada
Originally Posted By: Dignan
Originally Posted By: K447
Make a tidy ‘box’ with some art or nice photo on the front/sides, then hang/put the box where the antenna will work better.

Functional art wink

I'm pretty sure that if we hung art on the outside of our house we'd look like nutcases.
....
I was suggesting somewhere inside the house, like on a high wall with good exposure to the signal direction, or perhaps in the corner of a high window.

On the outside of the house, there are plenty of discreet plastic equipment boxes (weather sealed or not fully sealed) available that can protect bulky gear and be rather unremarkable/unnoticeable once installed.

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#372379 - 23/10/2019 19:41 Re: Coax question [Re: K447]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12318
Loc: Sterling, VA
Originally Posted By: K447
Originally Posted By: Dignan
Originally Posted By: K447
Make a tidy ‘box’ with some art or nice photo on the front/sides, then hang/put the box where the antenna will work better.

Functional art wink

I'm pretty sure that if we hung art on the outside of our house we'd look like nutcases.
....
I was suggesting somewhere inside the house, like on a high wall with good exposure to the signal direction, or perhaps in the corner of a high window.

On the outside of the house, there are plenty of discreet plastic equipment boxes (weather sealed or not fully sealed) available that can protect bulky gear and be rather unremarkable/unnoticeable once installed.

I figured that's what you were asking, I was just having fun wink

But yeah, between the positioning of our house, our neighbor's house, and the size/shape of the antenna, its current location is really the best one. If I were to get a box that enclosed this thing it would have to be about 2.5'Hx8"Dx4'W. I don't think that would pass the aesthetics test in our master bath, which would probably be the only indoor place it would work and even then...

In the end, I think the solution was really to remove the amplifier. I thought that I would need it for sure, given how far I am from the towers and how many trees/hills there are in the area. Antennaweb also made it seem like I'd have a lot of trouble too. But I'm just using the antenna now and it's working just fine. I'm getting the four main networks plus PBS and the CW, and there's not really any other channels I need. I've actually excluded the rest of the ones that I can receive because they're filled with garbage that I'll never watch.
_________________________
Matt

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#372380 - 23/10/2019 22:51 Re: Coax question [Re: Dignan]
K447
old hand

Registered: 29/05/2002
Posts: 797
Loc: near Toronto, Ontario, Canada
Originally Posted By: Dignan
... about 2.5'Hx8"Dx4'W. ...
I was assuming it was a flat panel type antenna. Sounds like you may have a Yagi style antenna, or something else rather three dimensional.

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#372381 - 24/10/2019 01:14 Re: Coax question [Re: K447]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12318
Loc: Sterling, VA
Originally Posted By: K447
Originally Posted By: Dignan
... about 2.5'Hx8"Dx4'W. ...
I was assuming it was a flat panel type antenna. Sounds like you may have a Yagi style antenna, or something else rather three dimensional.

Link in the OP wink
_________________________
Matt

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#372382 - 24/10/2019 12:17 Re: Coax question [Re: Dignan]
mlord
carpal tunnel

Registered: 29/08/2000
Posts: 14472
Loc: Canada
Originally Posted By: Dignan
ANTOP brand antenna (model AT-400BV).


You seem to have it working to your satisfaction now, so this follow-up is just a curiosity post:

The pre-amp for this antenna appears to be a little rectangular box integrated within the antenna "box" itself. As such, it does not appear to be removable at all. There is an extra "in-line" gizmo which serves as a DC power injection module, to supply remote power to the antenna.

The placement of the power-injection module is generally unimportant in the set-up: it can be right next to the TV if desired. All it consists of internally is a tiny capacitor to block the injected DC power from going to the TV set, and then a DC jack for power connected directly to the coax middle conductor and sheath, going towards the antenna/pre-amp.

With this physical configuration, it is possible to remove the power-injector from the setup, but the pre-amp itself seems to be hardwired into the antenna (that little rectangular box) and probably cannot be removed.

Some pre-amps still pass signal when not powered, though at a significant loss. Others cease to pass any meaningful amount of signal unless powered.

It is possible they have provided mis-information (aka. "they lied") in the description though, and the entire pre-amp circuitry could instead reside within the "power injection" module. Dunno.

Cheers


Edited by mlord (24/10/2019 12:19)

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#372383 - 25/10/2019 02:59 Re: Coax question [Re: Dignan]
K447
old hand

Registered: 29/05/2002
Posts: 797
Loc: near Toronto, Ontario, Canada
Originally Posted By: Dignan
Originally Posted By: K447
Originally Posted By: Dignan
... about 2.5'Hx8"Dx4'W. ...
I was assuming it was a flat panel type antenna. Sounds like you may have a Yagi style antenna, or something else rather three dimensional.

Link in the OP wink
Yeah, well, I clearly skipped that link on my first read crazy

Already suitable for outdoor mounting, never mind putting it in some other box. In your case it seems you have an acceptable combination of channel reception and mounting location.

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#372384 - 25/10/2019 03:01 Re: Coax question [Re: mlord]
K447
old hand

Registered: 29/05/2002
Posts: 797
Loc: near Toronto, Ontario, Canada
Originally Posted By: mlord
...
The pre-amp for this antenna appears to be a little rectangular box integrated within the antenna "box" itself. As such, it does not appear to be removable at all. There is an extra "in-line" gizmo which serves as a DC power injection module, to supply remote power to the antenna.

... it is possible to remove the power-injector from the setup, but the pre-amp itself seems to be hardwired into the antenna (that little rectangular box) and probably cannot be removed.

Some pre-amps still pass signal when not powered, though at a significant loss. Others cease to pass any meaningful amount of signal unless powered.

It is possible they have provided mis-information (aka. "they lied") in the description though, and the entire pre-amp circuitry could instead reside within the "power injection" module. Dunno.

Cheers
The product description mentions a Smart Switch with Long Range and Short Range modes. Unclear if that is a way of adjusting the amplifier gain or perhaps bypassing the amplifier built into the antenna unit, but it would seem to explain why it works with and without.

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#372386 - 26/10/2019 20:08 Re: Coax question [Re: K447]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12318
Loc: Sterling, VA
Originally Posted By: K447
Originally Posted By: mlord
...
The pre-amp for this antenna appears to be a little rectangular box integrated within the antenna "box" itself. As such, it does not appear to be removable at all. There is an extra "in-line" gizmo which serves as a DC power injection module, to supply remote power to the antenna.

... it is possible to remove the power-injector from the setup, but the pre-amp itself seems to be hardwired into the antenna (that little rectangular box) and probably cannot be removed.

Some pre-amps still pass signal when not powered, though at a significant loss. Others cease to pass any meaningful amount of signal unless powered.

It is possible they have provided mis-information (aka. "they lied") in the description though, and the entire pre-amp circuitry could instead reside within the "power injection" module. Dunno.

Cheers
The product description mentions a Smart Switch with Long Range and Short Range modes. Unclear if that is a way of adjusting the amplifier gain or perhaps bypassing the amplifier built into the antenna unit, but it would seem to explain why it works with and without.

I wonder if that "Smart Switch" is just the power switch on the in-line power injector...
_________________________
Matt

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#372387 - 26/10/2019 20:11 Re: Coax question [Re: mlord]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12318
Loc: Sterling, VA
Originally Posted By: mlord
Originally Posted By: Dignan
ANTOP brand antenna (model AT-400BV).


You seem to have it working to your satisfaction now, so this follow-up is just a curiosity post:

The pre-amp for this antenna appears to be a little rectangular box integrated within the antenna "box" itself. As such, it does not appear to be removable at all. There is an extra "in-line" gizmo which serves as a DC power injection module, to supply remote power to the antenna.

The placement of the power-injection module is generally unimportant in the set-up: it can be right next to the TV if desired. All it consists of internally is a tiny capacitor to block the injected DC power from going to the TV set, and then a DC jack for power connected directly to the coax middle conductor and sheath, going towards the antenna/pre-amp.

With this physical configuration, it is possible to remove the power-injector from the setup, but the pre-amp itself seems to be hardwired into the antenna (that little rectangular box) and probably cannot be removed.

Some pre-amps still pass signal when not powered, though at a significant loss. Others cease to pass any meaningful amount of signal unless powered.

It is possible they have provided mis-information (aka. "they lied") in the description though, and the entire pre-amp circuitry could instead reside within the "power injection" module. Dunno.

Cheers

I'm really not sure. At the moment I'm mostly working out some of the transcoding wonkiness between the HDHomeRun and my Plex server on my DS415+.

It did seem to make a small difference to have the injector on the antenna end rather than the tuner end. I got more channels. But it's definitely been most reliable without it and with the tuner directly next to the antenna, which has worked pretty well.
_________________________
Matt

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