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Splitters, Attenuators, Filters, Diplexers, Other Signal Gear

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539K views 2K replies 284 participants last post by  Gibsons 
#1 ·
Sounds to me like that channel 2 signal is very strong and just overdriving your system. I would add a channel 2 band stop filter http://www.tinlee.com/MATV_Filters.htm

CR7-Series: Semi-Adjacent Bandstop (any channel 5 to 800 MHz)


Tin Lee is a Toronto based company thats the best source around for traps and filters http://www.tinlee.com/
 
#1,219 ·
the booms are at least 24", screens extend up and down at bit.
maybe 1" between screens.
After I moved the antenna from 25' to 6', I gained more signal. Now I just need to walk the lawn and find a sweet spot.


I've thought about using 300 ohm line to joint to 2 91xg, and use a half wave balun in the middle of that line. If I can separate the fan dipoles from their internal balun connections I might try it this summer.

ok, back to filter and signal gear talk.
 
#1,220 ·
so after ordering a ch 19 jointenna and awaiting shipment, I remember I had ordered some notch filters for another experiment, so I decided to see what I could do.

my channel 19 antenna is some commercial brand GH. the main array is 2 91xg and a y10-7-13.

filters I had on hand were lpf 550, a notch 14-19, a notch 24-29 and a notch 19-23 as well as a UVSJ.

so from the GH, I go to a kitz 200 then out to a UVSJ with vhf terminated to the notch 24-29 to the lpf 550 then finally to the splitter.

from the array I go to a kitz 200 then to the notch 14-19 then to the splitter.

IT WORKS!!!

anyone know what kind of loss the jointenna has? I bet my solution has at least 4-5db insertion loss including splitter, maybe more.
 
#1,221 ·
anyone know what kind of loss the jointenna has?
Well, congratulations, first of all!

I've measured as little as .5 - .6 dB or so, to around 2.5dB, depending on channel and how well the the box was tuned. That's on the bandpass port; its >30dB on the 'band reject' a.k.a. 'notch filter' port. ( FYI, I usually find I can tweak modest imporvements over the factory supplied tuning. But there's a caveat here which is that length of cable attached and impedance matching does influence the 'optimal' tuning; there's no way for a factory setting to account for the infinite possibilities of attached cable+devices).
 
#1,222 ·
Some test results from the 7th order chebychev high pass filter prototype I built, referred to around post #1177.

With an FM transmitter ~ 1/4 to 1/2 mi from me, installing the filter inside the house
on the input of the Zenith DTT-901, I don't lose any TV Stations.
My three Edge channels, WPXJ-DT 23, CHCH-DT 18, and CBLT-DT 20 are still stable, and WNGS-DT on VHF Hi Ch 7 is still visible
at like -66 dBm on the analyser, so it must not be too bad insertion loss wise.
Looks promising for when spring comes and I can insert it between the Antenna and pre-amp input, where it belongs.
Should be able to aim right at that tower and not be bothered.

Installed in a Bud Project Box, should be able apply some RTV or silicone sealant, etc.

fm band as is, -30 dBm ref level, 10 dB / div, Centered on 98 MHz, 17 MHz Span

fm band attenuated with high pass filter in place.
 
#1,223 ·
Evening All,
I typically grab up antenna bits and pieces at flea markets, as I'm sure most here do. This past weekend I came up with piece I'd never heard of before, and I was hoping somebody might fill me in on some questions I have.

It's a PCT-NGNII-It1t--06 1-WAY TAP -6db

I've done the usual googling and found details here http://www.cencom94.com/gpage.html

But as I'm a novice, the obvious is alluding me. What is a drop tap and why are they used over just a splitter, or a distribution amp?

Thanks for any help.

Bobby
 
#1,224 ·
tap = you "tap" the signal with just a percentage of the total signal, leaving the rest to the main output.

That percentage you're tapping is rated in dB.

For a shared cable run in a big building, for example, you would not want to split the signal in half, then again in half, and so on, leaving the last subscriber with little signal left.

Under the same shared cable logic, you would not necessarily want to have a super 100x splitter where all subscribers are connected to. That could be a lot of wire you could save. You could decide to separate your runs in 16 legs, for example, and have each legs going through X apartments, use those taps between the units.

I hope I make sense, so I will love to be corrected if there's anything wrong here.
 
#1,228 ·
I have had problems with Ideal pwr pass splitters used outside. They seem to be made out of a porous metal that absorbs water. I've had to go out and replace 3 of them, and i know for sure the connections were sealed.
Better to buy a good one if used outside. AD makes a good one.
 
#1,229 ·
Finally got around to putting the homebrew high pass filter (post # 1222) up top at the input of my preamp today. All my edge channels are still stable, and can tune Canadian stations CHCH-DT and CBLT-DT over a much wider swing of azimuth than before. While moving the rotor in a 360, it's actually pretty tough to lose CBLT-DT now, even when it passes by the nearby FM transmitter. Analogs look a little better too. Significant improvement achieved.

edit: bring on that summertime tropo;)
Some quality readings after installing the homebrew hpf,
from the pc based tuner which is the worst tuner in the house.
* - edge chs
** - history of multipath issues
Code:
ch call   net		C/N dB
7 WNGS-DT ThisTV	23.0
14 WUTV-HD FOX 		27.5
18 CHCH-DT CHCH 	17.0 *
20 CBLT-DT CBC 		17.0 *
23 WPXJ-DT ION 		18.5 *
26 WNYB-HD TCT 		22.0
32 WNLO-HD CW 		26.5
33 WGRZ-HD NBC 		28.0
38 WKBW-HD ABC 		21.5 **
39 WIVB-HD CBS 		26.5
43 WNED-HD PBS 		23.5
49 WNYO-HD MyTV 	27.0
 
#1,230 ·
Jointenna Fine Tuning/Tweaking

Hi All:

Just added a channel 9 jointenna last week (and moved an existing alternate attic antenna to become channel 9-dedicated) for the upcoming digital switch for CBET (CBC) Windsor. The jointenna seems to work well, with no apparent signal strength loss or multipath problem (all signals are strong and steady) and digital channels 7 and 8 seem unaffected.

Since CBET-9 is still in analog, I can do A-B antenna tests with simple eyeballing, and something unusual caught my attention. With my previous antenna (pointed 35 degrees off-axis toward channels 7 and 8), channel 9 comes in around a 6 out of 10 in analog. With the now-dedicated channel 9 antenna going through the jointenna, it comes in around an 8.5-9 or so, but the picture has much more contrast to the limited snow present, while the picture going through the previous antenna (even though snowier) is much softer overall. It's almost as if the tv's sharpness control is turned all the way down on the previous antenna, while turned all the way up with the dedicated channel 9 antenna going through the jointenna. Or, it's almost as if the jointenna is slightly off-tuned.

I noticed re_nelson's post today at #26 in the Winegard 9032 thread (http://www.digitalhome.ca/forum/showthread.php?t=137678&page=2) about trimming the caps in his jointenna:

You'll likely be interested in the waveforms I saved a few weeks back that Trip Ericson archived on his RabbitEars site. This configuration was the 91XG and C5 aimed at Cedar Hill (site of Dallas area transmitters) and the Y10-7-13 (aimed north for KXII channel 12). The only waveform not flat across the top is KTVT's RF-11 signal due to the JoinTenna 0582. I've since tweaked the trim caps in the device and restored 11 to a nice flat top without adversely impacting channel 12.
After reading this, I thought I'd ask re_nelson (and the group in general) whether my jointenna could be slightly out of tune, and whether it's easy to tweak the trim caps yourself without any specialized equipment (and if so, how it's done) such as by simply eyeballing the picture on analog 9 and checking signal strengths on digital 7 and 8. In the digital realm, this would never be apparent to me (as it would probably never show up on my tv's signal strength meter), so I was wondering whether I should attempt a trim cap adjustment while channel 9 is still in analog. On the other hand, if the adjustments are more likely to get messed up if I attempt to adjust, I'd be inclined to just leave well enough alone, since my signal should now be plenty strong for the upcoming digital switch on channel 9. Also, perhaps this is just a normal characteristic (for analog stations) of using a jointenna.

Thanks in advance for your comments.
 
#1,234 ·
DirecTV "SWM" RF Splitters might be just what you're looking for:
http://www.sonoradesign.com/images/MSAT-Splitters.pdf
http://www.sonoradesign.com/images/sheet_sws_splits.pdf
http://www.sonoradesign.com/home.php?cPath=49&target=homeowners&osCsid=6inn9b98ckshujikjomnipcar0
Note that these are specifically designed for MoCA enabled households, with a port-to-port
isolation much less than the high isolation found in typical Cable RF Splitters.

FYI: MoCA "Whole Home Networks" is available in newer DVRs, Cable Boxes, PCs and some External Storage
Devices for internal distribution of either user supplied files or redistribution of provider provided programs.
 
#1,235 ·
Filter for Channel 6 but not FM Radio?

I'm getting some interferance on Channel 6, still haven't determined what it is. Will be investigating this weekend. If it's FM interferance, will be looking for solutions, since I don't want to use the trap on the CM7777, as I will be pulling in FM signals on this setup too.
 
#1,238 ·
Inter-modulation occurs in the first active device (transistor, etc). Therefore, filters should be used before that first stage.

Looking at your location, I don't see any licensed FM stations anywhere near your location that would likely interfere with channel 6.

Poke around this weekend and see if you can get any additional information.
 
#1,239 ·
Your cm7777 should greatly attenuate FM but not necessarily kill it completely, especially if you're having trouble with interference and FM end up being the culprit (it usually is)

You should give the cm7777 trap setting a try, and see what it does to channel 6 and FM before and after the change.
 
#1,242 ·
I believe I am getting interferance on channel 6 because... according to my TVfool report, both of the CTV stations in the area are showing significanltly lower signal strength than TVO on channel 6. Now that the 8200 is up an running, both CTV stations are crystal clear whereas TVO channel 6 is definately not. This weekend I will be looking closer at the interferance (what it looks like) to try and determine if it seems to be FM interferance.... If I still think it's FM, then I want to actually test what FM signals that I will actually be losing if I have to test/use the trap on the CM7777..
 
#1,243 ·
Oh. Interference on channel 6 not interference from channel 6. FM interference is the most common type of interference for channel 6 specifically. There are several other types of interference on VHF-LO as a whole that don't affect VHF-HI or UHF. The links stampeder provided are a great place to start.
 
#1,244 ·
Concept Setup

Hey guys, I've been mulling about this type of setup:


But would like feed back. Basically Target 1 would be Toronto, Target 2 would be Buffalo, based on my TVFool report (viewed here: https://sites.google.com/site/maycreates/ota-setup)

Setup in the attic. Currently my two Hoverman's are combined before a single CM-7777 preamp. Just like some input as to what negative effects (other than the possible overload issue) I could run into if I ran each antenna group on their own preamp, then combined further down the chain prior to distributing to the individual tuners. I may not even require the CM-3414, but just a 4-way splitter (would also help tone down signals if over amplified by the pre-amps).

UHF Antennas would still be my Gray Hovermans, VHF antennas would be some yet to be determined types, but most likely some DIY flavor. I can conceivably see overload issues due to over amplification. Just want some feedback as to whether I'm completely nuts, or if this is conceivable.

Stampeder, if this is not the right area, please move to where it would adequately go. Not sure if this is an amp question, or a OTA area reception question, or a splitter question...maybe it's a little bit of everything.
 
#1,245 ·
Marbles_00 your logic looks fine, especially with making sure the power supplies are dedicated to each preamp, but the added boost of the CM3414 distro amp might be overkill.
Marbles_00 said:
I may not even require the CM-3414, but just a 4-way splitter (would also help tone down signals if over amplified by the pre-amps).
Yep, I would try your plan without the CM3414 first (1-to-4 splitter instead) and then if it seems to require the extra oomph go ahead and try the amp but have a few 3dB to 6dB attenuators or some variable attenuators on hand for trimming down the signal at each of the tuners (especially tuner 3!)

Ideally the best practice is to test the signal strength/quality of each tuner based on the total coax length to it. Start with the longest and then go one-by-one to the shortest, in that order. Get the tuner with the longest coax run set "just right" and then attenuate the others in order, as needed. For example, the next tuner might need a 3dB, the next tuner after that 3dB, and the one with the shortest length 9dB (again, just examples). In your diagram the testing order would be 2, 1, 4, 3.

Since not all ATSC tuners perform alike it might even be worthwhile to put your best (most sensitive) tuners on the longest lines if that is at all possible.
 
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