Okmed,

The Winegard CA-8800 is a much better way of splitting the FM to your receiver. The loss is only 0.4 db, vs around 3.0db with a conventional splitter.:)

A diplexer, as used on this forum, is a band (frequency) separator/combiner device that looks (visually) very much like a splitter. What it does, though, is divide a single input into two frequency groups, each on its own output.

Eg. a "UVSJ" (UHF/VHF splitter/joiner) is a diplexer, which will separate the VHF frequencies (channels 2..13, plus FM radio) from the UHF frequencies (channels 14-70) of a coax line. These are commonly available at shops for $1.50 - $5.00 or so.

I use them here both ways around: for combining feedlines from UHF and VHF antennas together for a long run down from the tower, as well as for separating such signals where needed.

The other commonly available diplexer is for use with satellite dishes: it allows one to combine a regular OTA TV antenna feed with a satellite dish feed, so that they share a single coax cable from the outside. This works, because TV frequencies (54Mhz-800Mhz) do not overlap satellite LNB frequencies (generally 1-3GHz).

Cheers

I used a splitter before my tv to connect fm to my receiver and now I know I need to get a diplexer to reduce the loss to the tv. Is there a specific one I need or will anyone do?
I don't know of any commonly available FM<-->TV diplexers.
If you don't need VHF TV (channels 2..13), then a UVSJ diplexer (see previous post) will work, but that's probably not what you want.

For feeding FM from a TV setup, you're probably stuck with splitting the signal in half (conventional splitter). If the loss in signal strength bothers you enough, you could use an amplifier to boost the signal before splitting it. An antenna pre-amp is best, but a decent distribution amp could be used instead. Look for a low "noise figure" (no worse than 3dB) on the amp.

Cheers

Or, alternatively, use an A-B coax switch instead of a splitter. When listening to FM, switch it to (eg.) the "B" position. When watching TV, switch it back to (eg.) the "A" position. Crude tech, but it works.

The small all-metal slider style A-B coax switches are generally the best for signal quality.

I don't know of any commonly available FV<-->TV diplexers.
If you don't need VHF TV (channels 2..13), then a UVSJ diplexer (see previous post) will work, but that's probably not what you want.
Or better yet, use an "HLSJ". It will pass all VHF-HI & UHF channels on the "HI" side. This will only work if you don't need channels 2-6 though. I have tested mine with UHF channels up to channel 68, and it does not attenuate even the weakest of those high frequencies. It also offers very low insertion loss-0.4 db.

I use both a UVSJ, & HLSJ in my system. They work wonders!!

UVSJ-To combine separate UHF, & VHF antennas.
HLSJ-To filter out channels 2-6, plus FM. I have 3 FM stations 1/2 mile away, and the HLSJ makes for an excellent "full band" FM trap as well for my digital tuner.

Filtering out the strong FM signals improves both VHF, "& UHF " on my system.

Hope this helps;)

Filtering out the strong FM signals improves both VHF, "& UHF " on my system.
Yup, that can definitely help! Here, we devote a special antenna to our weakest UHF station, and the pre-amp has incredibly high rejection of the entire VHF+FM band from the signal. Nice and clean, that way!

Cheers

Thanks hoopitup2000 and mlord. Where would I find a "HLSJ" ?

Thanks hoopitup2000 and mlord. Where would I find a "HLSJ" ?
Just do a google search for "HLSJ". There are many places that sell them and they are very inexpensive. I don't believe they are designed for outdoor use, but not 100% sure.

Please let us know how it works out for you!!

Tinlee makes a TV/FM splitter/combiner (model number S7-TF) (http://www.tinlee.com/MATV_headend.php?active=4#MATVBANDSPLITTER).

I also discovered Winegard makes a FM Band Separator/Coupler (CA-8800) (http://winegard.com/offair/couplers.php).

I have tested mine with UHF channels up to channel 68, and it does not attenuate even the weakest of those high frequencies. It also offers very low insertion loss-0.4 db.

This is nice to know since according to Pico Macom's website (http://yhst-18278607509093.stores.yahoo.net/pico-0144.html), the high side is only supposed to pass 175~216 MHz. If this is indeed true, it would be good for me as my antenna doesn't do well with VHF-LO and I would like to add a separate antenna for that.

So a UVSJ can be used to "block" VHF channels ?

I think i have 2 vhf analog channels that are hampering my reception.

So a UVSJ can be used to "block" VHF channels ?

I think i have 2 vhf analog channels that are hampering my reception.

Yes, the UVSJ will block all VHF channels. Word of warning though, some DTV stations will be moving to VHF after the analog shutdown and this will block those as well.

does Sayal sell the UHF/VHF diplexers?

Does anyone know a company that makes good quality powered cable splitters?

Another option is to try to combine 2 antennas pointed directly at each tower. A signal combiner (basically a splitter in reverse) will penalize you about 4dB so if you can get more than 4 dB of additional antenna gain, it would likely be a better option. I don't know how much antenna gain an omnidirectional antenna has, but I figure it is about the same as a single loop.


When used as a splitter you will have a 3dB loss ( 3dB = half ) plus whatever internal component loss ( closer to .5dB at VHF/UHF frequencies with a high quality device ).

When the same device is used as a combiner you don't get the 3dB loss because you're not cutting the signal in half. You will get the sum of the two signals minus the internal component loss ( .5dB ).

When the same device is used as a combiner you don't get the 3dB loss because you're not cutting the signal in half. You will get the sum of the two signals minus the internal component loss ( .5dB ).

This is only true if you have identical antennas pointing in the same direction. As described at HDTV Primer (http://www.hdtvprimer.com/ANTENNAS/merging.html), when the antennas are pointing in different directions you end up getting reflections within the combiner resulting in:

1/4 of the signal reflecting back to itself,
1/4 of the signal reflecting to the other antenna, and
1/2 of the signal traveling through to output.


When combined with the internal loss, you end up with 3.5 to 4 dB of signal loss when used as a combiner.

http://www.digitalhome.ca/forum/showthread.php?t=101632

Any suggestions for easy-to-find (i.e. not mail-order due to high shipping costs) lowish loss baluns? For DIY indoor antenna use, so I especially can't afford 4-6dB loss. I don't see the CM one available by itself locally. Thanks.

As far as balun losses go: it may be obvious, but CHECK the balun before installing. I recently tried 2 brand new ones (supposedly reputable brands) and both were defective (open). Antennas still seemed to work, but very poorly and was likely only the coax doing the antenna job.

Have to agree with you there - baluns (a.k.a. matching transformers) are not the most predictably good items out there. :rolleyes: These days I have to wonder if The Source, WalMart, Zellers, etc. are just selling the same product under different brand names.

As 300ohm has mentioned elsewhere, if you can find original baluns from Japanese video consoles they have tested persistenly well for quality and low loss.

There's an antenna shop in Oshawa I think - Able Antenna(?) that might have good quality baluns:

http://www.digitalhome.ca/forum/showthread.php?t=23984