Splitters, Attenuators, Filters, Diplexers, Other Signal Gear

[majortom]

BCNU,
for kicks I tried what your proposing, sort of. Sort of meaning I didn't use a diplexer, but using the DC injector that comes with a Winegard AP 8700 preamp, I removed the "Wall Wart" Power Supply feed, and connected a dishnetwork satellite receiver in it's place to power the preamp. I then went to the Antenna installation screen, Menu 6,1,1 and flipped thru all the various transponders (to get the receiver to switch it's LNB Output voltage). It worked fine powering the preamp, and I didn't notice anything on the OTA signal as I switched transponders. also keep in mind obviously I wasn't attempting to actually receive any satellite signal. Just wanted to see if I could spot any strange behavior as the input voltage was switched by the sat receiver.

Around post 1896 of the preamp thread I brought up some issues I had with this device when I first got it. If ya read the subsequent posts I was able to resolve the issue myself, and it's still working fine here two years later.

http://digitalhome.ca/forum/showthread.php?p=1098866

[threeflags]

While rooting around my local surplus store ... I found what looks to be a 4 way Tap with a label of Tin Lee DC-482 on it. It has 1 female coaxial connectors for both side of the unit and 4 additional outputs on the middle face. Written on the face is the word "TAP" so I think its a 4 way tap.

Does anyone have any experience with this product? Or these products over using a regular splitter?

I'm thinking that this product may be better than using a 4 way splitter as it is a 4 way tap. I really never seen any TAPs in my local stores before. Not sure why there is an additional output on the other side. Could it be simply a way to pass the signal out once again?

The other concern is whether the tap will handle the frequency. Unfortunately I wasn't able to record the range but I recall it was under 1ghz ... more like 900 hz.

Anyway the store didn't have any price on it so they thought $5? Is that reasonable?

Setup.
DB8 with CM-7777 running on a 60 foot main fed to my 4 way splitter then out to further splitters (TVs & FM).

[roger1818]

threeflags, Tin Lee makes great stuff, and is typically very expensive (I would guess the DC-482 may cost over $100, so $5 would be a bargain). How useful it is for you is another question. The web page for their taps (including the DC-482) is here. It should also state the tap port loss (between 10 to 28dB for the DC-482) on the front of the tap.

Taps are typically used by cable companies and in commercial installations where you want most of the signal to travel through from the input to the output, but want to tap off a small fraction of the signal. For example a cable company would put one in a distribution box with the output going to the next box and the 4 taps serving 4 houses. This could be useful in a home if not all your drops go back to the distribution panel, but otherwise you are better off with a splitter.

[holl_ands]

Drop Tap is used in Cable systems to feed a daisy-chained set of drops, such as a neighborhood of homes. A VERY STRONG signal level goes to the first Drop Tap, where a port with a very high value of attenuation feeds that home (or group of homes via another splitter). A single coax on the primary output port feeds the NEXT Drop Tap location and so on, loosing signal strength as it goes through each Drop Tap. At the furthest away location, the signal level is much weaker, so one of the low attenuation output ports can be used to feed the local home (or group of homes):
http://www.atvresearch.com/techinfo/...0designing.pdf

4-Way DC-482 provides a VARIETY of attenuation choices on four outputs.
Tin-Lee specs said the range was from 10 dB to 28 dB of attenuation, but didn't say what the in-between attenuation values were. Typically you order a part with a specified MAX value (e.g. between 10 dB min and 28 dB max) and the resultant attenuation values are max, max-3, max-6 and max-9.....chosen to provide the closest to "spec" line level for each local drop. Fol. spec sheet for a similar product may help to understand:
http://www.tonercable.com/Products/tgt4
http://www.tonercable.com/assets/ima...le/TCE-TGT.pdf

So NOT very useful for OTA or in-home Cable applications....

[roger1818]

Originally Posted by holl_ands

So NOT very useful for OTA or in-home Cable applications....

In most cases I agree and certainly a 4-way tap has limited home applications. However, a 1-way tap in the range of 6 to 12dB can be useful for balancing the power when either splitting the power before your distribution panel or splitting to to a line that has additional splits further down the line (possibly for both a PVR and a TV tuner).

[threeflags]

Thanks for all of the excellent replies. It's too bad it won't work in my situation. However, using it as an attentuator does bring up some other options. Thanks again.

[gcd0865]

Hi All:

Was reading about filtering of undesired FM and other out-of-band signals at an outside tv antenna. I've noticed the popularity of FM traps and terminated HLSJs in strong signal areas, and the desirability of filtering new 4G LTE signals above 698 MHz where UHF tv channels 52-69 used to be. It appears that many inexpensive FM traps provide about 20 dB of attenuation across the FM band.

I seem to remember a posting (can't find it now) about an upcoming 174-698 MHz special tv bandpass filter for attenuating everything below/above (but presumably not between) the channel 7-51 VHF-high and UHF tv bands. Wasn't sure whether that product ever appeared on the market.

More recently, I've noticed recommendations of better-quality FM and other signal filtering (25-50 dB) by scanner enthusiasts for bringing out desired signals. Since I'm trying to receive distant (65-mile) tv signals while aiming through a full-power TV/FM transmitter farm at 11 miles distance, I was wondering whether investing in better-quality filtering is likely to improve tv reception more than a standard inexpensive FM trap, as it seems to have done in these threads for scanner reception (including airband at 108-136 MHz, weather band at 162.475 MHz and police/fire at 400-480 MHz):

http://forums.radioreference.com/pas...p-airband.html
http://www.eham.net/reviews/detail/3086
http://www.parelectronics.com/fm-broadcast.php
http://www.tinlee.com/Graph_ALL_FM_filters.php#graph6

Thanks in advance for any comments/suggestions.

Edit - Looks like TinLee has indeed introduced its CF7W VHF-HI to UHF bandpass: 174-700 MHz Pre-selector filter, as well as a double-wide bandpass filter specifically for VHF-high plus the old UHF band (up to 806 Mhz; not sure if they've modified it to stop at 698 MHz):
http://www.tinlee.com/bandpass_filte...?active=3#CF7W
http://www.tinlee.com/PDF/CF7W-174-700%20graph.pdf
http://www.tinlee.com/Graph_CF7W.php (2nd graph down)

[holl_ands]

Here's my original post re 4G LTE Band Reject Filter requirements for North America:
http://www.digitalhome.ca/forum/show....php?p=1388395

If you search for "LTE Band Reject Filters", you'll find several, but they all seem to be targeted for Europe (and elsewhere), where their LTE Band starts at 800 MHz, rather than 700 MHz for North America.

Updated link for Pico LPF-700 CABLE TIER Filter....NOT all that effective against lower LTE Band:
http://picodigital.com/_docs/_data_s...-SERIES_DS.pdf

Note that new Tin-Lee CF7W-174-698 Bandpass Filter attenuates 700 MHz (2 MHz above Ch51) by only 2 dB (good job) and provides more than 40 dB of rejection on 740 MHz, so it's providing lots of attenuation against AT&T Towers on 735-746 MHz, with only minimal to moderate amounts of attenuation against AT&T Cellphone & Tablet transmissions on 704-716 MHz (see my next post).

Call or email Torsten Wolf at Soontai and ask about detailed frequency response specs for their new 700 MHz Band LTE Filter and where/how you can get one:
http://www.soontai.com/LTE-filter.html

[holl_ands]

I also made a series of posts re how 4G LTE Transmit Towers and a cacophony of Handheld 4G LTE Cellphones, Hotspots, iPADs, iPAD Minis and other Tablets can interfere with DTV reception, based on various CRC & U.S. lab tests and the European experience with their 800 MHz LTE Band.:
http://www.digitalhome.ca/forum/show....php?p=1389931

I provided technical information re AT&T and Verizon 4G LTE, including their operating bands. Interference to DTV stations will primarily be due to desensitization on the higher channel numbers (e.g about 45-51) due to "Taboo" Adjacent Channel Interference and also 3rd Order Intermodulation noise, but could also affect lower channels:

AT&T uses lower part of the 700 MHz Band for uplink from users: 704 - 716 MHz and data to users on downlink: 734 - 746 MHz (Band 17):
http://en.wikipedia.org/wiki/E-UTRA#...nel_bandwidths

Verizon's 4G LTE frequency assignments are higher, with data to users on downlink: 746 - 757 MHz and uplink from users: 776 - 787 MHz (Band 13).

You could advise other TV viewers in your home to refrain from using 4G Data Services if you KNOW that their (probably AT&T) 4G LTE Cellphone and/or Tablet transmissions are the source of your problem....and/or add an LTE Filter as close as possible to the Tuner's input....NOT near the Antenna.

I provided a link to see if a 4G LTE Cell Tower was close to your home, in which case you MIGHT benefit from an LTE Filter. If you are more than about 5 miles away, I doubt you need one.

[roger1818]

Originally Posted by holl_ands

Call or email Torsten Wolf at Soontai and ask about detailed frequency response specs for their new 700 MHz Band LTE Filter and where/how you can get one:
http://www.soontai.com/LTE-filter.html

They also have 650 and 680 MHz Low Pass Filters, which may work well for those who don't have channels all the way up to Ch.51 (here in Ottawa we top out at Ch.43, which is 650MHz).

http://www.soontai.com/LPF.html