Morgan Hill, CA: Recommended OTA HD Reception Testing Procedure - Page 3 - AVS Forum
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post #61 of 78 Old 06-19-2014, 02:34 PM - Thread Starter
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Great, it appears that I'm learning a little... Thanks Calaveras.

Continuing with this thread on testing protocol.... With the RCA preamp, might there be any benefit from having the power induction further up the chain, more near the antenna, as opposed to at the end, just before the TV or box?
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post #62 of 78 Old 06-19-2014, 03:38 PM
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No, unless you have several hundred feet of coax, perhaps.
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post #63 of 78 Old 06-19-2014, 03:50 PM - Thread Starter
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Originally Posted by ProjectSHO89 View Post
No, unless you have several hundred feet of coax, perhaps.
When it's routed in the proposed, most direct path, it will be about 20 feet to the DVR (looking to be the CM DVR+). From there, about 10' of HDMI to the TV...

I have power in the attic, so it's an option. But, given what you shared, I won't bother as it seems that it would have minimal to no benefit on such a short run...

For those who have experience with this RCA preamp (TVPRAMP1R), think it will be problematic that one of my antennas is strictly UHF (ClearStream4) and the other is both VHF & UHF (RCA ANT751), as opposed to a dedicated VHF antenna? I didn't see a compact VHF only antenna, so went with the RCA ANT751...

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post #64 of 78 Old 06-19-2014, 06:30 PM
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think it will be problematic that one of my antennas is strictly UHF (ClearStream4) and the other is both VHF & UHF
Nope. Just make sure the switch is set to "Separate". The VHF port will simply reject any UHF coming from the 751.
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post #65 of 78 Old 06-19-2014, 10:32 PM - Thread Starter
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Originally Posted by ProjectSHO89 View Post
Nope. Just make sure the switch is set to "Separate". The VHF port will simply reject any UHF coming from the 751.
Thank you ProjectSHO89. The instructions don't quite help with such a set-up. It states to use "common" with one antenna that does both VHF and UHF, and to use "separate" with two antennas, but where one is VHF and one is UHF. Not what I have...

Thanks again.

A scan said it found like 51 channels. However quite a few didn't produce a picture and a few others were not stable. Still, much better than anticipated... I still feel that there is more signal to be had with orientation tweaks and spacing between antennas. I attach a photo that shows the current crude set-up. Yes, the spacing is not ideal. When antennas are too near each other, how does that usually manifest itself (negative attribute)?

Metal - We hear that it's important to not have metal touching antennas, yet masts are typically metal (ferrous content). Do people paint their masts, or put some type of non-metallic coating on them, at least in the area where it attaches to the antenna? Just curious...
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post #66 of 78 Old 06-20-2014, 03:42 AM
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Quote:
Originally Posted by TonyB1996:
but where one is VHF and one is UHF. Not what I have...
Yes, it is. You're simply ignoring the UHF from the 751. You will only be getting the VHF signals from the 751. There is no practical way to do otherwise.

The vertically oriented mast, as long as it's not touching the elements, isn't an issue. It's metal that is horizontally or diagonally oriented (with respect to the elements ) in front of or near the elements that are to be avoided.
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post #67 of 78 Old 06-20-2014, 07:18 AM
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Quote:
Originally Posted by TonyB1966 View Post
A scan said it found like 51 channels. However quite a few didn't produce a picture and a few others were not stable. Still, much better than anticipated...
The most important thing is how many different stations you receive. The number of channels is just the sum of all the sub channels on a much lower number of stations.


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I still feel that there is more signal to be had with orientation tweaks and spacing between antennas. I attach a photo that shows the current crude set-up. Yes, the spacing is not ideal. When antennas are too near each other, how does that usually manifest itself (negative attribute)?
I'd get the ANT751 up off the roof and I assume you're not going to leave the preamp in that position. Antennas that have metal too close can have degraded patterns which would show up as lower gain, lower front-to-back ratio and higher VSWRs. The problem is none of those will be obvious. It would show up as reduced performance that you'd be unaware of.


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Metal - We hear that it's important to not have metal touching antennas, yet masts are typically metal (ferrous content). Do people paint their masts, or put some type of non-metallic coating on them, at least in the area where it attaches to the antenna? Just curious...
It's not that other metal can't touch an antenna, but you don't want horizontal pieces of metal close enough to couple to the horizontal elements to degrade the antenna performance. What's behind the antenna is much less important than what is above, below or in front of it.
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post #68 of 78 Old 06-20-2014, 07:22 AM
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Quote:
Originally Posted by TonyB1966 View Post
I didn't see a compact VHF only antenna, so went with the RCA ANT751...
http://www.antennasdirect.com/store/...V-antenna.html
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post #69 of 78 Old 06-20-2014, 10:16 AM
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Quote:
Originally Posted by Calaveras View Post
It's not that other metal can't touch an antenna, but you don't want horizontal pieces of metal close enough to couple to the horizontal elements to degrade the antenna performance. What's behind the antenna is much less important than what is above, below or in front of it.
One thing Tony should watch out for. I noticed that one of his antennas is just above the peak of the roof. There's often metal flashing at the peak of the roof, under the shingles.
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post #70 of 78 Old 06-20-2014, 05:00 PM - Thread Starter
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Thanks everyone. Have been in the attic and on the roof a fair amount. Pretty hot, especially in the attic...

With respect to the pre amp settings and connections, I was simply saying that the provided instructions are for two situations:

1. One antenna, that is both VHF and UHF and
2. Two antennas, where one is VHF and the other UHF

I'm of course using two antennas, with one having both VHF and UHF. From what little searching I did, it seems that there are fewer VHF only antennas, than other offerings. Oh, for whoever found that ClearStream 5 VHF antenna, I did find that one too at some point. Thank you. I suppose it would have been a good match in some respects with the CS4 I'm using for UHF. It's twice the price as the RCA ANT751, and I prefer the lower profile of the RCA, requiring less vertical space. I'm not asking much of the RCA ANT751 - just to get channel 8's NBC and ABC, about the easiest get from my location. I understand that any UHF picked-up by the ANT751 will get filtered-out on that port, which is fine as there's not much down there in that frequency range or channels of interest...

With the coax no longer routed through the sliding glass door, but upward through the attic, things are starting to take form. The experimentation has revealed that I can achieve the objective. I get ABC (35 and 8), NBC (8), and PBS (50) quite well. FOX (44) and CBS (29) would be the really nice to get, but right now, with an SNR in the 20's, I'm reluctant to say I can get those reliably. I have some hope though...

I now have the pre amp mounted on the mast, just loosely though. I'll get the rubber boots on all the terminations points soon, once I get the DVR (probably DVR+), and refine the coax's run. The mast is currently extended with a slip sleeve-like union and seems a bit wobbly. Maybe a screw will do the trick, but I still might go the galvanized pipe route...

Oh, the build quality of the RCA ANT751 is a bit suspect. The 3rd element is very loose. There is nearly 3/16" of play. The pop rivet is shot. So, at some point I'm going to drill it out and use a machined screw and nut with blue Locktite. There's another loose element too, but not nearly as bad...

Thanks for those who chimed-in on the metal question. Makes a lot of sense. I appreciate the knowledge share. I remember when running speaker wiring, and whenever I needed to get near a Romex cable (power), going across at 90 degrees was the approach to take; and it did make a difference.

Chuck, really good observation and point (lower antenna just off the peak of the roof). From what I can tell, I don't think that is the case here. The roof has ridge vents, and the system doesn't seem to be metal, but some type of plastic. Not sure how to be certain without removing some material, which I'd prefer not doing... I guess since that lower antenna is "only" tasked to get channel 8, and with a pretty solid SNR of 25, I suppose there's not much reason for concern, at least at this time...

This all has been educational and somewhat fun too. Thank you.

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post #71 of 78 Old 06-20-2014, 05:12 PM
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Originally Posted by TonyB1966 View Post
The roof has ridge vents, and the system doesn't seem to be metal, but some type of plastic. Not sure how to be certain without removing some material, which I'd prefer not doing.
If the ridge flashing is galvanized steel, it will deflect a compass you bring near it. But it could also be aluminum.

Chuck
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post #72 of 78 Old 06-20-2014, 05:27 PM - Thread Starter
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Originally Posted by Chuck Tribolet View Post
If the ridge flashing is galvanized steel, it will deflect a compass you bring near it. But it could also be aluminum.

Chuck
Brilliant. I have a telescoping magnet that I was going to try from inside the attic too... Since this is the worst time of day to be in the attic, maybe much later tonight.

The ridge vent might also be copper. Sort of has that color, so it seems. On our other house, I actually adhered scrap copper, strips and pennies along the ridges, particularly in the shady areas where moss would be more likely to grow. Pretty neat trick...
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post #73 of 78 Old 06-20-2014, 06:01 PM
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Brilliant. I have a telescoping magnet that I was going to try from inside the attic too... Since this is the worst time of day to be in the attic, maybe much later tonight.

The ridge vent might also be copper. Sort of has that color, so it seems. On our other house, I actually adhered scrap copper, strips and pennies along the ridges, particularly in the shady areas where moss would be more likely to grow. Pretty neat trick...
Unless it's a really good magnet, it may not attract through the plywood. (BTW, a good source of
GOOD magnets is defunct disk drives. There's a really strong magnet in there that the head coils push against. You can set one on a 1.5" thick desk, and drag it around with its twin underneath. Flip the twin over, the magnet on top flips. Nerd amusement.)

And didja know that since 1983 (and some 1982 pennies), pennies have been a copper-plated zinc alloy?
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post #74 of 78 Old 06-20-2014, 06:57 PM - Thread Starter
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Unless it's a really good magnet, it may not attract through the plywood. (BTW, a good source of
GOOD magnets is defunct disk drives. There's a really strong magnet in there that the head coils push against. You can set one on a 1.5" thick desk, and drag it around with its twin underneath. Flip the twin over, the magnet on top flips. Nerd amusement.)

And didja know that since 1983 (and some 1982 pennies), pennies have been a copper-plated zinc alloy?
Being into numismatics, and having saved pennies in glass Alhambra bottles and long neck wine bottles for years I was indeed aware Chuck. I have "steely" pennies from the WWII years, and other neat stuff, all in boxes somewhere...

As I recall on the roof's ridge, from within the attic, there's a decent sized gap for the air to escape. I think that is enough space to get a magnet through, right to the material... I also have a rather large magnet (250 lb) that can use on the shingle side too. I keep old hard drives in a shoebox, so that's good to know...
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post #75 of 78 Old 06-20-2014, 07:43 PM - Thread Starter
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Also, realistically, what should one expect in performance improvement after introducing a pre amp such as the RCA TVPRAMP1R? The only measure I have is from the TV - SNR.
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post #76 of 78 Old 06-20-2014, 09:42 PM
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You should see higher SNRs especially on the more marginal stations. With such a short coax run the improvements may not be all that much, especially on VHF.
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post #77 of 78 Old 06-20-2014, 10:03 PM - Thread Starter
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Alrighty, that helps. Thank you. Seeing about a bump of 1-4 with the SNRs. On ch 35 though (ABC), it went from 21 to 26. I thought FOX and CBS were improved, up to a 20 SNR, but now around 16 to 17, so breaking-up...

When connected to the DVR and some slack in the coax run still, it will ultimately be about 10-15 feet shorter. Marginal improvement at best I know. Is it worth considering any other type of additional amplification? Apparently the DVR+ has signal strength %, so that will be nice to see...

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post #78 of 78 Old 06-22-2014, 11:45 AM - Thread Starter
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Anyone, where might be a good place to source those rubber weather-proof coax boots that slide over the terminations? It seems that these must be in place before the terminations are made, so I'd like get some soon... Thanks much.

Edit / Add: I'll be using Rescue Tape, for which I already have a roll. Great stuff BTW...

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