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UHF Notch Filters.. - Page 2

post #31 of 49
Thread Starter 
Does anybody know which of the notch filters will filter out the bands used by cable between VHF 13 and UHF 14

I just found out that my Sony MRDD1 will do cable channels in this bandwidth, and my newer digital modulators are very easy to set for this or the higher bandwidths.

--David
post #32 of 49
The filter commonly called a "lifeline filter" passes 54-88 Mhz and 174-216 Mhz while blocking the rest. You can use any old U/V splitter combiner for the UHF, highpass side.

There are "off-the-shelf" 230 Mhz lowpass filters that still open up all cable channels starting around 27 or 28.

If your MRDD1 will develop cable channels below 65, they will each be 2 Mhz off-frequency vis-a-vis UHF when your TV tries to tune them, but the "capture range" of nearly modern TVs is wider than that, so you shouldn't have a problem tuning them.

On concern, however, is that there are aeronautical frequencies in that range that are monitored closely by the FCC, and if you are backfeeding these channels into your antenna downlead, they may get broadcast by your reception antenna. I'm not sure of this, but I think the aeronautical concerns stop at cable channel 54, so you should be able to squeeze in three or four channels from there to cable channel 64.
post #33 of 49
Quote:
Originally Posted by DavidEC View Post

Does anybody know which of the notch filters will filter out the bands used by cable between VHF 13 and UHF 14

I just found out that my Sony MRDD1 will do cable channels in this bandwidth, and my newer digital modulators are very easy to set for this or the higher bandwidths...

You don't need any filters to clear the superband and hyperband, which is what they call the UHF channels below UHF channel 14. If you can't find clear channels below UHF 14, cable 65, then you have overloaded an amplifier and you are sufferung from intermodulation, which you should remedy.

What are you using for amplification, and where is it inserted?
post #34 of 49
Quote:
Originally Posted by Rick0725 View Post

if you insert the channels there (between ch 13 and 14) you would need to switch the tuner in set up between cable on and off to receive them. then the uhf channels wont work then vice versa...correct?

He'd leave his TV set on cable tuning. TVs have capture ranges greater than 2 Mhz, so he would just have to learn the new channel numbers he'd select to find the UHF stations. Simply add 51 to UHF channels 14-43, and 56 to UHF channels 44 and up.

KSAS channel 24 will now be on 75, KSCW-33 will be on 84, KTQW-49 will be on 105, modulated channel 53 will be on 109, or the modulator can be switched to cable 109, etc.
post #35 of 49
Thread Starter 
Well it looks like I now have two choices which widen my choices...

But it seems that both will need a notch filter because I am picking up something ....

Choices:
)A( Go for the low UHF cable band of channels 54 -> 64
)B( Go for the High UHF band of channels 54 -> 64 [cable 112 - 125]

Trouble is I am getting side-banding on both choices...

As pointed out before I am getting local VHF TV in the upper high uhf, and when I was just doing 'white noise test' I am hearing two different stations in the lower UHF... one I am sure is a radio station as it is music and tripped the 'stereo' info marker on the test TV, the second one I am unsure of its source but I think it was somebodies ham or am talk radio??.

Also by having the notch filter it should prevent my signals from being rebroadcast by my antenna.

The plus side of switching the TV's to the "CABLE" setting the LP-UHF stations tune in sharper and with less week signal noise.

-David
post #36 of 49
You are NOT picking up enough stray signals in the cable channels 23-54 band or of the UHF channels above UHF channel 54 to warrant adding a wideband filter because there is very little to pick up. I've added channels to a few hundred systems in both urban and rural markets, It's not like I'm guessing at what the technical hurdles are. If you are under an FM tower, then you add an 88-108 Mhz filter for $4. If you notice, watching a neighbor's cable TV, that there is interference on channels 14-22 (which are between 6 and 7) you insert a cheap A-I filter (AKA, midband reject filter) to avoid having those otherwise irrelevant signal overloading your amplification.

If you have "interference" across those available bands, then you are creating or intensifying it. A filter will not necessarily eliminate whatever it is you are experiencing if it is the by-product of amplifier intermodulation.

If you are too close to analog transmitters on channels 3, 5 or 10, then you put in a U/V separator/joiner and put a ten dB attenuator pad (under $3) on the VHF line, then couple them back together.
post #37 of 49
Thread Starter 
Quote:
Originally Posted by AntAltMike View Post

You are NOT picking up enough stray signals ......
If you have "interference" across those available bands, then you are creating or intensifying it. A filter will not necessarily eliminate whatever it is you are experiencing if it is the by-product of amplifier intermodulation.....

Mike -

I hate to tell you this .._BUT_.. on both of the test TV's (both Wal-Mart Specials 13" and a 19" Daewoo) neither even had a coxal cable attached... this was and is just 'over the air' pick up of signals, by their built in tuners..

--David
post #38 of 49
Thread Starter 
Quote:
Originally Posted by AntAltMike View Post

He'd leave his TV set on cable tuning. TVs have capture ranges greater than 2 Mhz, so he would just have to learn the new channel numbers he'd select to find the UHF stations. Simply add 51 to UHF channels 14-43, and 56 to UHF channels 44 and up.

KSAS channel 24 will now be on 75, KSCW-33 will be on 84, KTQW-49 will be on 105, modulated channel 53 will be on 109, or the modulator can be switched to cable 109, etc.

UGG!
Tried to get my HDTV to tune in the off air HD/DTV signals with the tuner set for 'cable' not 'air' and it would only see the standard broadcast channels and not the HD/DTV signals even if the set is advertised as having a ATSC & QAM Digital Television Tuners.
So I am back to using only the UHF band and trying to filter/block the line..
post #39 of 49
Quote:


Tried to get my HDTV to tune in the off air HD/DTV signals with the tuner set for 'cable' not 'air' and it would only see the standard broadcast channels

Is this with your antenna or cable TV?
post #40 of 49
Thread Starter 
Quote:
Originally Posted by Rick0725 View Post

you are correct the tuner when switched to "cable on" will scan

-analog cable channels
-qam cable channels


with cable on
will not scan uhf analog off air and atsc uhf off air channels. vhf 2-13 will scan though.

Well not fully true.. as most all of my off air non-hd UHF stations were found and assigned a cable channel with only one non-hd uhf 24 (531.25MHz) not being assigned a 'cable channel'

--David
post #41 of 49
Thread Starter 
Quote:
Originally Posted by Rick0725 View Post

Agreed. I cringed when I first read the recommendation.
... ... ...
I find the situation just too compromising for my tastes and would rather program and filter appropriately...not in cable mode.

Well so far I have not been able to find a filter(s) in the price range that I can afford.

Either they are 'thousands of dollars ' made for the head end of a full fledged cable system or the back end of a multi-dwelling system.

Not for a single line system [as I was told mine setup is call in the 'industry'(??)].

And I have see kits on 'eBay' but they are all for the low UHF bands not the HIGH UHF bands that I am trying to work with. {back to trying to work with UHF channel ~17, 22,~ 38, 43, 58~, ~61~64~67~ inserting 8 channels}

I can get by using UHF 22 in my system due to the fact that on the high side I have a full two open channel and the low side is a full power DT/HD signal that does not seem to be bleeding into 22 as I have a clean white noise signal...

If only I did not have a clean 'white noise' in the channels 58->

And while I would like to get a two filters one each high pass and a low pass filter with the break point being above UHF55 but in the range of UHF 58.

--David
post #42 of 49
Quote:
Originally Posted by DavidEC View Post

Well so far I have not been able to find a filter(s) in the price range that I can afford.

Either they are 'thousands of dollars ' made for the head end of a full fledged cable system or the back end of a multi-dwelling system.

Not for a single line system [as I was told mine setup is call in the 'industry'(??)].

And I have see kits on 'eBay' but they are all for the low UHF bands not the HIGH UHF bands that I am trying to work with. {back to trying to work with UHF channel ~17, 22,~ 38, 43, 58~, ~61~64~67~ inserting 8 channels}

I can get by using UHF 22 in my system due to the fact that on the high side I have a full two open channel and the low side is a full power DT/HD signal that does not seem to be bleeding into 22 as I have a clean white noise signal...

If only I did not have a clean 'white noise' in the channels 58->

And while I would like to get a two filters one each high pass and a low pass filter with the break point being above UHF55 but in the range of UHF 58.

--David


Have you considered a Jointenna tuned to channel 58. They say that they are good for about 3 channels wide. You might be able to get 57, 58, and 59 through a single filter. A second filter for 63 would add 62, 63, and 64. If you use two, they should be at least 5 channels apart.
post #43 of 49
Thread Starter 
Quote:
Originally Posted by Tower Guy View Post

Have you considered a Jointenna tuned to channel 58. They say that they are good for about 3 channels wide. You might be able to get 57, 58, and 59 through a single filter. A second filter for 63 would add 62, 63, and 64. If you use two, they should be at least 5 channels apart.

What is a " Jointenna " ??

And where does one order one?

--David
post #44 of 49
Quote:
Originally Posted by DavidEC View Post

What is a " Jointenna " ??

And where does one order one?

--David

http://www.warrenelectronics.com/ant...Jointennas.htm

Look here and scroll down to Jointenna:

http://www.hdtvprimer.com/ANTENNAS/glossaryG.html
post #45 of 49
Thread Starter 
Quote:
Originally Posted by Tower Guy View Post

http://www.warrenelectronics.com/ant...Jointennas.htm

Look here and scroll down to Jointenna:

http://www.hdtvprimer.com/ANTENNAS/glossaryG.html

Thanks for the link.. but after two weeks I have not gotten a reply from their tech support on the turn around time or cost for my project?

Maybe my spam filter kicked it??

--David
post #46 of 49
Thread Starter 
Update on project... In short I have sort of given up....... mixing external antenna with internal system with so many of the HDTV signals taking up so much of the UHF band locally

Riddle me this... now I have no external antenna connected to my internal set up...

Yet I am getting interference from some where... yesterday AM all channels were clear and clean.. now two of my internal channels are "Fuzzy" and full of interference:
[1] One channel has a wave (or as my wife calls it a finger print) moving over the image.
[2] One channel has a rolling interference from top left to bottom right of the screen.

I have not moved or changed anything in the last 24hours...

--David
post #47 of 49
Thread Starter 
I think that maybe one of my single channel modulators is going bad.... as I plug the A/V cables into another/new modulator set for the same channel and the interference goes away....??

But I am just going to have to leave things as they are for now... as I work the next 15 days straight before I can try adding any filters or subtracting any line amps in the system setup.

--David
post #48 of 49
I'm having the same difficulty in your very similar situation... I could not foresee spending a lot of money for ASTC modulators. tuners or filters.

I have several Over The Air channels that I flip through frequently, some are not even shown on paid subscription. I am trying integrate the channels for my digital & analog TVs, DVRs, and security cams.

I have purchased two signal combiners. One each for channel 3 and 4. I also have single, double, and quad agile UHF modulators.

I am working on cutting off my ties with subscription services. I only down to a couple of subscribed channels left one modulated on 4 other on 64. I am not willing to rent more boxes to get a couple more channels or have a box for each TV. Just too much. 10-20 dollars a box per month for each tuner or TV is not realistic. This adds a lot of money per month, worst to even mention I could no longer connect to the cable without having their box to tune to a channel.

I've used RabbitEars to help get a good idea of local stations, and is used widely.

My difficulty is modulating to a free channel and not interfering with a neighboring channel. For the most part my modulated channels are receiving interference. I bought another modulator thinking it may be going bad, but it is not the case.

When I add a notch/pass filter in the system it clears up the signal, but I lose my HDTV broadcasts over several channels.
I tried and attenuated the modulator with a variable attenuator without success to clear channels.

On a couple TVs that have newer tuners, when I switch to cable for my antenna, I lose half my digital programming, even after an variable amplified signal. The local modulated channels are still not clear.

With a few modulators, I would like to keep my modulated channels sequenced, but it may not be realistic.

58, 60, 62, 64 & 61, 63
post #49 of 49
You need to go to the Seattle thread and post your TV fool reception analysis using the most precise location information you have available, since mislocating your residence by even a small amount will significantly alter the calculations of your receptionn where you are. That will enable people to figure out what broadcast signals you need to keep and which you can suppress or avoid.
Edited by AntAltMike - 4/20/13 at 9:25am
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