Where can I get a low-pass filter approx. 75MHz? - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 9 Old 08-25-2008, 06:37 PM - Thread Starter
Member
 
HalloweenWeed's Avatar
 
Join Date: Dec 2007
Location: Maine, USA
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Entire explanation:

I am trying to combine standard NTSC antenna signal with new DTV converter box output. The DTV has a separate special antenna, gets only UHF (we are in outer fringe area). We cannot get any NTSC channels below 6. The DTV converter boxes puts out chan. 3 & 4. I am combining the outputs using a coax splitter (in reverse). It works good except it ruins channel 8.

So I am looking for:

A Low-pass COAX filter approx. 75MHz to allow only channels below 5 to come in from the DTV converter box, to filter out channel 8 interference. I don't know where I might find one of these, I tried radio shack & Newark electronics. Theoretically, if I added such filter between the NTSC DTV converter box output & the NTSC antenna combiner (splitter in reverse), it would block said interference of any channel above 4.

George Carlin: "IsnÂt it a bit unnerving that doctors call what they do ÂpracticeÂ?"
HalloweenWeed is offline  
Sponsored Links
Advertisement
 
post #2 of 9 Old 08-25-2008, 08:18 PM
Senior Member
 
crkpot's Avatar
 
Join Date: Dec 2007
Posts: 379
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by HalloweenWeed View Post

Entire explanation:

I am trying to combine standard NTSC antenna signal with new DTV converter box output. The DTV has a separate special antenna, gets only UHF (we are in outer fringe area). We cannot get any NTSC channels below 6. The DTV converter boxes puts out chan. 3 & 4. I am combining the outputs using a coax splitter (in reverse). It works good except it ruins channel 8.

So I am looking for:

A Low-pass COAX filter approx. 75MHz to allow only channels below 5 to come in from the DTV converter box, to filter out channel 8 interference. I don't know where I might find one of these, I tried radio shack & Newark electronics. Theoretically, if I added such filter between the NTSC DTV converter box output & the NTSC antenna combiner (splitter in reverse), it would block said interference of any channel above 4.


So your saying you combined the signals from the output of your new OTA digital converter box with the signals of your VHF/UHF antenna? The digital converter box only outputs it's signal on channel 3/4 so the only thing you should need to do is put a channel 3 or 4 trap on your old antenna line to keep it clear for the converter box to send signal on that frequency.

Here's a ch3 trap:
http://www.weisd.com/store2/ATVMN-3.html

Here's a ch4 trap:
http://www.weisd.com/store2/ATVMN-4.html

If I had to guess I would say the splitter is what's causing problems on CH8, splitters are not made to combine signals like. Maybe something like this would work better.
http://www.solidsignal.com/prod_disp...om=Large#xview

I'm just trying to help so these are my suggestions, hopefully they're close to a solution. You could always use an A/B switch too.
crkpot is offline  
post #3 of 9 Old 08-25-2008, 08:45 PM - Thread Starter
Member
 
HalloweenWeed's Avatar
 
Join Date: Dec 2007
Location: Maine, USA
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Problem with switch is we are recording multiple channels with 3 recorders, switch would limit channels to record.

George Carlin: "IsnÂt it a bit unnerving that doctors call what they do ÂpracticeÂ?"
HalloweenWeed is offline  
post #4 of 9 Old 08-25-2008, 09:07 PM - Thread Starter
Member
 
HalloweenWeed's Avatar
 
Join Date: Dec 2007
Location: Maine, USA
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by crkpot View Post

So your saying you combined the signals from the output of your new OTA digital converter box with the signals of your VHF/UHF antenna? The digital converter box only outputs it's signal on channel 3/4 so the only thing you should need to do is put a channel 3 or 4 trap on your old antenna line to keep it clear for the converter box to send signal on that frequency.

Here's a ch3 trap:
http://www.weisd.com/store2/ATVMN-3.html

Here's a ch4 trap:
http://www.weisd.com/store2/ATVMN-4.html

If I had to guess I would say the splitter is what's causing problems on CH8, splitters are not made to combine signals like. Maybe something like this would work better.
http://www.solidsignal.com/prod_disp...om=Large#xview

I'm just trying to help so these are my suggestions, hopefully they're close to a solution. You could always use an A/B switch too.

Forgive me if I'm wrong, but don't traps remove a channel? These would only remove ch3 or ch4 from the feed COAX. I am not having problems with ch2, 3, or 4 in the combined signal; they appear perfect.

About the switch, see my separate post (below) dated 8/26 at 11:45p.m.EDT.

As for the antenna combiner: "Always join identical antennas for the best results." And really, I think this is just a splitter relabled & repackaged and sold for more $. I have proven the backwards splitter works, and good signal pass-thru too, I just need to filter out the ch8 interference (from the DTV converter box).

I suppose I could maybe use a ch8 trap to trap the ch8 interference from the DTV box:
http://www.weisd.com/store2/ATVMN-8.html

Unfortunately, this is sold out and no longer available. Any more ideas, anyone else?

George Carlin: "IsnÂt it a bit unnerving that doctors call what they do ÂpracticeÂ?"
HalloweenWeed is offline  
post #5 of 9 Old 08-26-2008, 12:29 AM
Senior Member
 
crkpot's Avatar
 
Join Date: Dec 2007
Posts: 379
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by HalloweenWeed View Post

Forgive me if I'm wrong, but don't traps remove a channel? These would only remove ch3 or ch4 from the feed COAX. I am not having problems with ch2, 3, or 4 in the combined signal; they appear perfect.

About the switch, see my separate post (below) dated 8/26 at 11:45p.m.EDT.

As for the antenna combiner: "Always join identical antennas for the best results." And really, I think this is just a splitter relabled & repackaged and sold for more $. I have proven the backwards splitter works, and good signal pass-thru too, I just need to filter out the ch8 interference (from the DTV converter box).

I suppose I could maybe use a ch8 trap to trap the ch8 interference from the DTV box:
http://www.weisd.com/store2/ATVMN-8.html

Unfortunately, this is sold out and no longer available. Any more ideas, anyone else?


Ok I think I understand your problem now. Even though the converter box is supposed to output on ch 3 or 4 it is bleeding over to ch 8. I have seen this with digital cable boxes now that I think about it. That ch 8 trap probably would work for your situation, but short of having a custom made low pass filter I don't know what else would work for you in that situation.
crkpot is offline  
post #6 of 9 Old 08-26-2008, 07:33 AM
AVS Special Member
 
egnlsn's Avatar
 
Join Date: May 2007
Location: Taylorsville, UT
Posts: 2,221
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 31
Quote:
Originally Posted by HalloweenWeed View Post

Entire explanation:

I am trying to combine standard NTSC antenna signal with new DTV converter box output. The DTV has a separate special antenna, gets only UHF (we are in outer fringe area). We cannot get any NTSC channels below 6. The DTV converter boxes puts out chan. 3 & 4. I am combining the outputs using a coax splitter (in reverse). It works good except it ruins channel 8.

So I am looking for:

A Low-pass COAX filter approx. 75MHz to allow only channels below 5 to come in from the DTV converter box, to filter out channel 8 interference. I don't know where I might find one of these, I tried radio shack & Newark electronics. Theoretically, if I added such filter between the NTSC DTV converter box output & the NTSC antenna combiner (splitter in reverse), it would block said interference of any channel above 4.

Perfect application for an SC-3.

The SC-3 is a sophisticated multi-filter channel combiner enabling locally originated channels (3 (cable box)) with spurious outputs to be cleaned up and balanced with off-air signals resulting in a clean adjacent channel home distribution system.

CIAO!

Ed N.
egnlsn is offline  
post #7 of 9 Old 08-26-2008, 10:21 AM - Thread Starter
Member
 
HalloweenWeed's Avatar
 
Join Date: Dec 2007
Location: Maine, USA
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by egnlsn View Post

Perfect application for an SC-3.

The SC-3 is a sophisticated multi-filter channel combiner enabling locally originated channels (3 (cable box)) with spurious outputs to be cleaned up and balanced with off-air signals resulting in a clean adjacent channel home distribution system.

That would work! But for two converter boxes on RF COAX I will need both the SC-3 & SC-4. I plan to have at least 3 converter boxes, one will have to be connected to my DVR via composite (or S-vid cable if CM-7000) to record that channel on that particular recorder only.

If I had a low-pass filter, only 1 unit would have to be installed (might be cheaper). But this may not be feasible as I cannot yet locate such a unit on a low budget. So unless I hear any better suggestions soon, I will order these (Holland Electronics SC-3 & SC-4). Thank you egnlsn.

George Carlin: "IsnÂt it a bit unnerving that doctors call what they do ÂpracticeÂ?"
HalloweenWeed is offline  
post #8 of 9 Old 08-26-2008, 08:23 PM - Thread Starter
Member
 
HalloweenWeed's Avatar
 
Join Date: Dec 2007
Location: Maine, USA
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by egnlsn View Post

Perfect application for an SC-3.

The SC-3 is a sophisticated multi-filter channel combiner enabling locally originated channels (3 (cable box)) with spurious outputs to be cleaned up and balanced with off-air signals resulting in a clean adjacent channel home distribution system.

I just got my 2nd DTV converter box, and lo & behold, the two interfere with each other on channel 3 no matter what the settings, even with one set to 4. Tried all combinations & pass-thru too, complicated by I need to leave them on constantly for VCR/DVR automatic recording. So egnlsn's solution is the ideal one, hopefully it will end the cross-interference between the two units also. I even tried pass-thru both ways, NOTE: The Digital Stream 9950 only passes NTSC signal thru when the unit is off (pass-thru useless to me)!

If anyone is interested in the results with the SC-3 & 4, post a message here, and I will let you know how it went after I install them.

FYI: the units are Digital Stream 9950 & LG Zenith DTT-901.
I plan on buying the CM-7000 later for my third and final channel (I can't get any more than 3 useful channels where I live presently, in West-"central" Maine). I will then hook up the CM-7000 via S-vid cable to a dedicated DVR.

Thanks egnlsn and AVS forum.

I think we may be done here this thread.

George Carlin: "IsnÂt it a bit unnerving that doctors call what they do ÂpracticeÂ?"
HalloweenWeed is offline  
post #9 of 9 Old 09-06-2008, 01:57 PM - Thread Starter
Member
 
HalloweenWeed's Avatar
 
Join Date: Dec 2007
Location: Maine, USA
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Moderator: You may lock this thread as this issue has been resolved, and has not been gathering interest.

George Carlin: "IsnÂt it a bit unnerving that doctors call what they do ÂpracticeÂ?"
HalloweenWeed is offline  
Reply Cable, Digital Cable - Non-HDTV

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off