Splitters, Attenuators, Filters, Diplexers, Other Signal Gear - Page 115 - Canadian TV, Computing and Home Theatre Forums

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post #1711 of 1748 (permalink) Old 2016-06-04, 07:42 PM
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Quote:
Fox was the one I was worried about. Its usually 20ish dB on a single TV. I feared adding a regular splitter would leave me with 20dB-3.5dB = 16.5dB or a very margin signal. Was hoping the CM3412 would overcome that but I guess not.
If you have a 20 dB SNR with one TV, then the 3412 should have compensated for the split. You can add an attenuator if the 3412 11.5 dB gain is a little too much for the tuner, but I agree with chinadog, you shouldn't even need the 3412.

DB8e > 7777 > coax 60 ft > grounding block > power inserter > 3412 > TVs

In theory, you shouldn't even be able to receive WUTV Fox on real channel 14, but tvfool reports are known to be wrong for 2Edge signals. It has a Noise Margin of -31.7 dB, which is below the Thermal Noise Floor of -15 dB NM, and only 33 kW of 1000 kW ERP are sent in your direction:
TV Fool

Fox also has adjacent channel interference from CHCH on real channel 15.

Ah, yes; I see that chinadog already mentioned that. A very directional antenna can attenuate 15 when aimed at Fox, but maybe not enough.

CHCH is 53 dB stronger than Fox. The max allowed for adjacent interference is 33 dB. But if you already have been able to receive Fox, the tvfool simulation is wrong.

165 - 129 = 36 degrees

The DB8e has a null at about 20 degrees, and a secondary lobe at 36 degrees. The 91XG is a little better, with 10 to 15 dB down at 36 degrees.

That would require a 20 dB antenna null for CHCH or the Two Antenna Trick, or a custom Tin Lee filter.

CITS -69.6 dBm + 15 dB ant gain = -54.6 dBm = -5.8 dBmV

max input of 7777 = 15 dBmV; OK

-54.6 dBm + 24 dB amp gain = -30.6 dBm

-30.6 dBm + 11.5 dB 3412 gain = -19.1 dBm; not quite enough for tuner overload unless you have another source of strong local signals.
Quote:
I feared adding a regular splitter would leave me with 20dB-3.5dB = 16.5dB or a very margin signal
Did you actually try that?

I just read your original post, so I had to correct my math.

Splitters, Attenuators, Filters, Diplexers, Other Signal Gear

If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 2016-06-04 at 09:56 PM.
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post #1712 of 1748 (permalink) Old 2016-09-15, 09:15 AM
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Back in post 1647 of this thread I asked a question and I ended up getting a Holland DCWG-9 which has work well for me but I still need to improve it.

Here's my project.

I have 2 signals (RF 15 and RF 35) in the opposite direction of all my other stations. RF35 is weak, RF15 is very strong. I have a 2nd antenna and 2 Tin Lee filters (I think they call then channel injectors to the masses). The DCWG-9 splits the signal so that most goes to the RF35. I connect them in series with the feed from the main antenna and voila, it works most of the time for all channels.

The issue - one of the channels on my main antenna is on RF14. RF15 even with 9db attenuation from the DCWG-9 has enough ACI to blow away RF14 at times. Last night was one of those times. By simply unscrewing the RG6 between the DCWG-9 and the RF15 Tin Lee filter, the RF14 signal returned. So I believe I need to further attenuate RF15.

Given that RF35 is weak, should I get a DCWG-20 or even a DCWG-30 so that I weaken RF15 and strengthen RF35? Should I also get attenuator(s) for the run from the tap to the Tin Lee filter? I'm a little confused over how to estimate how much attenuation of RF15 I need. I have to order the stuff from the US so I want to get it "right the 1st time" and not buy too much or the wrong stuff (I realize there's some trial and error here but I want to be in the right ballpark).

Not sure if this is useful but I'll add some numbers my tuner told me.

With DCWG-9 /RF15 cable in place

RF 15 SNR 32
RF 14 SNR 20 (approximately - checked again right now and this is the level but the channel is locked at the moment)

With DCWG-9 /RF15 cable unscrewed

RF 15 SNR 0
RF 14 SNR 25

Thanks for any insights.

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post #1713 of 1748 (permalink) Old 2016-09-15, 10:45 AM
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Incomplete information....can you DESCRIBE how your components are configured, esp how you are using the DCWG Directional Couplers rather than simply inserting an Attenuator on the output of the Ch35 Antenna...and why TWO Tin-Lee Channel Injectors??? Are they AC-7 Antenna Signal Injectors....or something else? Also, I need to see your TVFool Report to understand what is going on....

Holland DCWG Directional Couplers, see pg 85:
http://www.hollandelectronics.com/Holland_Catalog.pdf

Tin-Lee AC-7 Antenna Signal Injectors:
http://www.tinlee.com/MATV_headend.p...IGNALINJECTORS

Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands
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post #1714 of 1748 (permalink) Old 2016-09-15, 11:02 AM
 
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SNR, as displayed by the TV set, is not an accurate proxy for signal power, it is measuring a different attribute.

When signal levels are moderate or strong, the SNR typically maxes out around the mid 30's. Further increases in power have no effect on the SNR until you reach the point of distortion from over-driving the tuner's input.

When signals are very weak to weak, the effects of the automatic gain controls (AGC) inside the tuner distort the shape of the signal power vs SNR curve, especially as the signal power approaches the tuner's lowest pickup threshold.

At certain range of power levels, there is a modest correlation between the numbers, but it definitely is not a linear relationship across the board.

Antennas Direct Tech Support
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post #1715 of 1748 (permalink) Old 2016-09-15, 11:26 AM
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Yes, they are AC-7's. ".. why TWO Tin-Lee Channel Injectors??? ... " One for RF15, one for RF35

- Antenna1 is aimed roughly at 100 (a bit south of due east)
- Antenna2 is aimed roughly at 200 (a bit south of SW) right at the RF35 transmitter (RF 15 is a few degrees away). Neither RF15 or RF35 could be received with antenna1 which is optimized for all other stations (17 stations incl. RF14, antenna is my DB4e and it works fantastic as is - not planning to touch it again ).

Cabling ...

- Antenna2 to DCWG-9 "in"
- DCWG-9 "-9 dB" goes to AC-7 (RF15) input
- DCWG-9 "out" goes to AC-7 (RF35) input
- Antenna1 to the "All channels" of AC-7 (RF15)
- AC-7 (RF15) output to the AC-7 (RF35) "All channels"
- AC-7 (RF35) output to the tuner


As for ".. rather than simply inserting an Attenuator on the output of the Ch35 Antenna .." I don't want to do that - I think I need the attenuation on the cable from DCWG-9, "-9 dB" goes to AC-7 (RF15) input

Thanks!

A-D DB4e & CS5, CM 4221 & 7778, TiVo Premiere & Roamio
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post #1716 of 1748 (permalink) Old 2016-09-15, 11:47 AM
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Sorry Holl_ands, forgot to mention right click on my username and my homepage is my tvfool.

BTW, my issue has a lot of commonality to what was discussed in post 1709/1710 - same stations.

A-D DB4e & CS5, CM 4221 & 7778, TiVo Premiere & Roamio
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post #1717 of 1748 (permalink) Old 2016-09-16, 08:26 AM
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Holl_ands, now that I'm looking at the data on my own tvfool, my RF15 channel could be reduced 30 dB and still be in the yellow zone. So swapping out the DCWG-9 for a DCWG-30 may do the trick? Or more conservatively, swap in a DCWG-20 and get a few 3 dB attenuators to make small adjustments if necessary?

Am I on the right track?

A-D DB4e & CS5, CM 4221 & 7778, TiVo Premiere & Roamio
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post #1718 of 1748 (permalink) Old 2016-09-16, 06:02 PM
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El Gran Chico,
Is it possible that WCMH from Ohio may be causing you some grief occassionally due to ducting? What time was your last issue receiving WUTV? I realize the below post is from sep 2nd, but was pretty good ducting last night too, around here at least. Could be a contributor.
You are on a backlobe of WUTV, correct?
OTA: Great Lakes Area...

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post #1719 of 1748 (permalink) Old 2016-09-16, 06:42 PM
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MajorTom, I get WUTV pretty much 24X7X365. If it disappears, I unhook the cable from my DCWG-9 to my AC-7 (RF 15) and I'm good again. (of course, that takes out CHCH for the rest of the house).

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post #1720 of 1748 (permalink) Old 2016-09-17, 10:54 AM
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MajorTom, the more I think of it, you may be on to something. Antenna2 (for RF15 and RF35) is likely getting some "dirty" RF14 either from WUTV (at a sharp angle) or from a distant station. So attenuating my "DCWG-9 to AC-7 (RF 15)" cable would reduce this interference I think. The AC-7 doesn't entirely filter out adjacent channels.

It would be interesting to see if CHCH (RF15) went off the air temporarily and I had my "DCWG-9 to AC-7 (RF 15)" cable connected how the WUTV (RF14) signal behaves. That said, usually the 2 stations play well together in my setup, so if RF14 is ok, it doesn't prove anything. However, if it RF14 fails to lock, the interference itself would be the culprit and not RF15 per se.

Side note - Tin Lee's specs show there could be effects like this on adjacent channels so I'm not surprised about this, just trying to manage it better.

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post #1721 of 1748 (permalink) Old 2016-09-17, 06:51 PM
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Well I do know that CH 20 from London, ON has been creeping in here intermittently all
summer long. Such that I had to make sure my antenna is facing more north, to stay away from the ducting over Lake Erie, if I wanted CBLT to be stable.

It's quite obvious when that's happening here, because RF 19 TVO will be normal SNR, when RF 20 CBLT is degraded if I aim that way.
They are normally within +/- a dB of each other. Plus it's been an abormally warm summer, and the lakes are the warmest they've ever been this time of year...why I mentioned it.

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post #1722 of 1748 (permalink) Old 2016-09-23, 02:30 PM
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Quote:
Originally Posted by holl_ands View Post
See fol. post, incl. two other posts before it and after it re Available LTE Filters:
The Official AVS Antenna and Related Hardware Topic! - Page 547 - AVS Forum | Home Theater Discussions And Reviews
NOTE that an LTE Tower transmitting at HIGH Power levels would need to be within about 2-miles to cause interference to HIGHER UHF Channels....and many Towers are at LOWER levels, which increases the range of possible interference....and 2G, 3G, GSM Towers et. al are on MUCH Higher Freqs and hence are NOT a problem...

BTW: We have NO IDEA how effective CM LTE Filter is compared to OTHER LTE Filters, whose mfrs have actually published MEANINGFUL specs:
The Official AVS Antenna and Related Hardware Topic! - Page 547 - AVS Forum | Home Theater Discussions And Reviews
Charles Rhodes (TV Technology Magazine) measured Frequency Response of CM Stand-Alone LTE Filter. It provides about 50+ dB Insertion Loss against ATT+Verizon Cell Towers [734-758 MHz]....but there is significant LOSS on Upper UHF Frequencies....so Do NOT use one unless you NEED IT:
Out-of-Band Interference: Myth or Reality? | TvTechnology

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post #1723 of 1748 (permalink) Old 2016-09-27, 09:36 PM
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Update to my post 1712 - ISSUE SOLVED!

By my TV Fool report, I estimated my RF15 signal could withstand much more attenuation so I swapped out the DCWG-9 for a DCWG-24 I ordered and arrived today. The results ...

1) the RF35 signal (CHCJ) improved by 1 dB as the specs predicted
2) the RF15 signal (CHCH) was weaker as expected but still fairly strong - well within acceptable levels
3) the RF14 signal (WUTV) is much better (by about 5 dB by my tuner's measure) - pretty much at the same level as I had with the "DCWG-9 (-9 db tap) to AC-7 (RF15) input" disconnected

Since I was ordering from afar, I also bought a 3 dB and a 6 dB attenuator just in case the DCWG-24 wasn't enough alone. I experimented with both on the now "DCWG-24 (-24 db tap) to AC-7 (RF15) input" cable. The 6 dB attenuator very noticably reduced RF15 - probably too much, so replace it with the 3 dB. As one one would think, it showed a slightly reduced RF15 signal (vs. no attenuator between the "DCWG-24 (-24 db tap) to AC-7 (RF15) input) by the tuner's measure , but slightly improved the RF14 signal so I left it in place.

So now I have a spare 6 dB attenuator and a DCWG-9 but more importantly, a better setup for CHCJ and WUTV while keeping CHCH at a "strong enough" level. :-)

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post #1724 of 1748 (permalink) Old 2016-11-27, 12:24 PM
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It's been 2 months since I adjusted my setup.

Results:

0 drop outs on RF 14 (WUTV) watching live or recording
0 drop outs on RF 15 (CHCH) watching live or recording

but i did notice that on RF 33, I had more frequent drop outs. I did some experimenting and found that the RF 35 TinLee AC-7 appeared to cause some minor 2nd adjacent interference as the spec indicates. I swapped out the 3db attenuator on the RF15 AC-7 for the 6db and redeployed it to he RF 35 AC-7 input. Now all of RF 14, 15, 33, 35 are solid!

Lessons learned:

- if you have a TinLee AC-7, respect the 1st and 2nd adjacent specifications
- attenuators can be your best friend when using a TinLee AC-7

A-D DB4e & CS5, CM 4221 & 7778, TiVo Premiere & Roamio
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post #1725 of 1748 (permalink) Old 2017-02-27, 08:58 AM
 
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Newbie Seeks splitter recommendation

Hi, I am new to the OTA world, having cut the cord last September I made do with what I know now is referred to as "Digicrap" I bought at Factory Firect, not knowing any better.

I had never found it particularly satisfying, my OTA usage was small compared to streaming, but would like to watch dinner time news on City-TV. Some days it would be good, some days it would be splotchy, some days unusable.

My chief issue has been location, I live in Upper Burlington by Upper Middle/Walkers in a condo on a ground level unit facing N/NW with the entire building between me and the optimal signal area. Condo rules prevent me from mounting on outside walls , and the Digicrap would definitely violate the esthetic rules. I only had a few places I could place it , and got some good quality channels that I don't watch, occasionally some fringe channels (for me anyway like WIVB, and the 7 series of ABC Buffalo).

Finally after wasting many hours the last couple weeks to try and find optimal places to get what I want and failing I came here. Found out the truth about Digicrap and decided to take a chance on Antenna Directs Clearstream C2. It has made a big difference once I found a sweet spot that looks ok propped on a table on balcony.

I now get all the channels I wanted plus CFTO on VHF, City that seems reliable, CBC, Global, TVO, CHCH, YesTV, CtV2, CW & Bounce, 3 PBS, plus clear WIVB, and splotchy ABC, Laff & Escape.

Now to crux of matter (sorry for the background book) I get those on my main TV, but on a second TV (using a normal splitter) I get splotchy WIVB, no 7 series, and a signal on CFTO that looks more like a test pattern.

Both TV's have identical lengths of good RG6 wires , and are basically in same exact position on either side of wall, with splitter on the wire just before going into wall and up to TV's. I onow TV tuners vary, and the Main set is by far the better TV, but I would still like to improve the TV signal in bedroom. Plus I want to feed another signal to a mostly unused kitchen TV. I have read that regular splitters do have signal loss and want something that allows max signal to reach all TV's equally. Splitter is a regular cable splitter though I tried another I recently bought that says better for HDTV up to 2GZ - but in reality makes no difference so I am returning it.

I had tried a Pre-Amplifier on old setup , and lost all channels. It had worked somewhat when using the antenna indoors It also was made by Digicrap. I don't think that's what I want now anyway. Just a good splitter, that will either send full signal equally or maybe boost a bit but not at cost of losing anything else either.

If you have any suggestions I would appreciate it, again sorry for the bloated background info.

Cord Cutter -> OTA: Clearstream C2V, Channel Master 3414,
Stream -> Apple TV, Chromecasts , Android box.
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