Balm,

Since ATSC signals have a dynamic range of about 80 dB, a 30 dB attenuation may not be enough to knock a signal completely out regardless of the TVfool forecast (which, will good, are not always accurate enough to actually predict signal levels). You'd really need to view the signal on either a spectrum analyzer of a signal level meter to get a fair idea of how much the signal is being attenuated.

For an accurate assessment of attenuation, you'd need a proper vector network analyzer.

You'd really need to view the signal on either a spectrum analyzer of a signal level meter to get a fair idea of how much the signal is being attenuated.


i did that with the UHF, digitals, using the receiver signal meter, and here to no change on any of the channels, while connected to the VHF leg, and UHF leg capped - but im not sure on the signal meter exactly how much attenuation it takes before translating to a drop on that meter...


thanks

Since most receiver's meters measure digital signal QUALITY, not signal strength (power), they aren't well suited for doing the testing you described.

FYI: Spec sheet for UVSJ and HLSJ from Holland Electronics says
>25 dB rejection:
http://www.hollandelectronics.com/catalog/upload_file/Filters-Diplexers.pdf

Although specs for HLSJ from Pico Macom are no longer on their website,
they can still be found here (>20-22 dB Rejection):
http://www.solidsignal.com/pview.asp?mc=03&p=HLSJ&d=Pico-Macom-HLSJ-VHF-Band-HighLow-Antenna-SeparatorCombiner-%28HLSJ%29&c=Signal%20Splitters&sku=HLSJ

Since the FM frequencies are located between channels 6 and 7 I would assume that a UVSJ would work better than an ordinary splitter (since a splitter would lose 3.5 db) to peel off the radio stations to my receiver (I'm using a CM4228 which picks up VHF hi). Am I correct?

When used as a band splitter/separator, the UVSJ will "peel off" everything below the UHF band (470 MHz) on the UHF port and everything above channel 13 (around 230 MHz) on the VHF port by 25-40 dB. As long as you have ONLY UHF TV stations to contend with, then it's fine (and easy) to do as you propose.

However, if you have any type of pre-amp or distribution amp installed, you likely have enough signal to tolerate the 3.5 dB loss in a conventional splitter.

Since the FM frequencies are located between channels 6 and 7 I would assume that a UVSJ would work better than an ordinary splitter (since a splitter would lose 3.5 db) to peel off the radio stations to my receiver (I'm using a CM4228 which picks up VHF hi). Am I correct?
Yes, it will work much better than a splitter, if what you want is for FM to go one way (along with all of VHF), and UHF-only to go the other way.

No good though if you want to watch VHF TV along with the UHF.

The UVSJ finally worked for me, and dramatically.

I’m very close to the CHCH transmitter (11.0, 36.0, plus digital signals), and expected distant channels were not coming in, i.e., WNYO (49.1).

Thankfully to DHC members, I scored a couple of UVSJ splitters with the intention of reducing the strong/very close VHF signal (11.0) that might be disrupting the weaker/distant ones (WNYO- 49.1). So I tried the UVSJ splitters in various ways: before joiner, after splitter, before and after splitters/joiners, direct line (w/o splitter/joiner), etc., but nothing worked significantly, and resigned myself to thinking the UVSJ didn’t work in my situation.

It should be mentioned that I am also using a CM3414 amp which gave me a better lock on some digital UHF channels, but not the more distant WNYO and ION. I never tried the UVSJ after the amp b/c the amp itself gave me increased signal strength.

Just this week I got a new TV and the first thing I tried was reception on my weak station (WNYO), and it came in. Why? I first thought it was the tuner, which is different than my other TVs. But now I realized it was because this TV, which has the longest coax line and has multiple joiners, was receiving an attenuated signal (weaker CHCH), and thus WNYO could come in, which it did.

So with this in mind, I tried the UVSJs after the drop amp for each separate TV, and viola, it worked! WNYO came in solidly on my two other TVs, from 0% to 40%, and ION was pixilating. SUCCESS! SUCCESS!

THANK YOU DHC MEMBERS!

:cool:

goforit, where did you find the UVSJ's?

They were passed on to me by a DHC member, sorry I can't remember. Safari Electronics in TO might have them. mlord should know, and/or might have some. You might want to pm him.

I just put attenuators right at the television, at it seems to work wonders for me.
I'm in the same boat as you. Is a UVSJ a better attenuator? I currently have a 8 db on my shortest length set, then a 6 db on the next longest, and a 3 .db for my longest run.
Now you have peeked my interest.

The UVSJ is sort of an attenuator- but it really knocks down either all UHF signals or all VHF signals- in the range of 20 to 30 db. Can also be used as a joiner- VHF and UHF antennas.

which port do you go to? Did you tap into the VHF side and cap off the UHF? I have one nasty analog on channel 10 that could be doing the same as channel 11 CHCH.
If you have a chance could you take a pic and post it to your picture library?

FYI: Attenuation charts for Tin Lee's UV7 UHF/VHF Splitter/Combiner:
http://www.tinlee.com/PDF/UV7%20data%20sheet.pdf

They also make the LH7 Lo-VHF/Hi-VHF Splitter/Combiner (sorry no chart):
http://www.tinlee.com/MATV_headend.php

Seems like the loss is not too great- 16 to 18. The UVSJ boasts about 20 to 30, with only .5 insertion. I thought higher loss would be better.

On the way home from Ottawa today I stopped by our forum sponsor (great place) and picked up a few UVSJ's to test the recent findings that goforit found for the Hamilton area.
I am pleased to say it has worked wonders for me here in London. Two to three channels occupy the VHF band here but I live so close to channel 10 CFPL tower that I suspected it caused issues with my fringe digital Erie channel's.
I tried the UVSJ's as suggested after my CM 3414 just before each television, and voila! channel 24-1 WJET RF 24 came in, and 66-1 WFXP RF 22 also.
dang, I really would like to thank you guys.
note: the signals are an improvement to what I had, but the signals are still in and out during the day. This is still a major break through for my set up.

Excitement only an OTAer can understand.

Cheers!

They also make the LH7 Lo-VHF/Hi-VHF Splitter/Combiner (sorry no chart):
http://www.tinlee.com/MATV_headend.php

Digging a bit deeper finds...

LH7 specs: http://www.tinlee.com/Diplexers.php?active=3

Table of standard LH7 Diplexers: http://www.tinlee.com/Diplexers.php?active=3#TABLE

Example graphs: http://www.tinlee.com/Graph_LH7_LH7S.php?active=3

And some other interesting stuff: http://www.tinlee.com/PDFs.html

I recently got a second TiVo HD receiver and am not sure about the best method to connect my Antennas to my receivers.

I have two Channel Master 4228’s stacked and I’m considering splitting them and using one antenna for each receiver, this way avoiding having to split the cable or use an amp.

I stacked the antennas in hopes of boosting my reception to FOX in buffalo but got no noticeable signal strength increase to my Buffalo stations. I did however gain 20% signal strength to Global, CHCH and SUN TV.

What I’m curious to know before I split the antennas is if although I did not gain any noticeable signal strength to my Buffalo stations is it possible that by having the larger antennas surface gathering area that I’m less likely to loss my signal on bad weather days. Which could mean that keeping the Antennas stacked and splitting the cable even if it requires adding an amp could be the best option?

In short should I add a splitter and feed both receivers from my stacked Antennas or split the Antennas and use one Antenna for each receiver?

Splitting the antennas reduces Gain by about 2.5 dB - was that "good enough"???

Adding a Preamp to the ganged antennas will improve the System Noise Figure by 5-10 dB,
since the Loss in the coax plus the Tuner's Noise Figure are REDUCED by the Preamp's Gain:
http://www.digitalhome.ca/forum/showthread.php?p=888368
plus whatever "space diversity" Gain there may be due to extended reception surface area.

Milton, ON is far enough away not to worry about overload desensitization, let us know the results....