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post #1 of 24 Old 11-15-2007, 10:48 AM - Thread Starter
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What I would like to do is mount 2 of the 'Antennas Direct DB2' models, and a VHF antenna in my attic. Each facing in in a different direction so as to optimize signal. Then I'd want to combine these 3 signals to 2 coax cables. One cable runs directly to the main TV, the other runs to the utility room to be split to the other potential TV's in the house.

I know I will lose a portion of the signal if mounted in the attic, but that's where I really want it.

The DB2 model is 'UHF only' (which gets very good reviews), hence the inclusion of a separate VHF antenna.

I live about 15-30 miles from most broadcasts I'm looking for.

Presently I'm receiving 3 channels with rabbit ears on top of the TV in my basement, so I'm hopeful I can grab a few more with the proposed setup.

One of my biggest concerns with the proposed setup is 'ghosting' potential. Should that be a concern?

My Zipcode is 05478. I've done the antennaweb.org and tvfool.com, both very helpful. I got the reviews of antennas from hdtvantennalabs.com.

So, can I? And if so what are the splitter recommendations? I had someone tell me I can just use a splitter backwards, can you do that?.

Thanks
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post #2 of 24 Old 11-15-2007, 11:15 AM
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Quote:
Originally Posted by jhortonvt View Post

What I would like to do is mount 2 of the 'Antennas Direct DB2' models, and a VHF antenna in my attic. Each facing in in a different direction so as to optimize signal. Then I'd want to combine these 3 signals to 2 coax cables. One cable runs directly to the main TV, the other runs to the utility room to be split to the other potential TV's in the house.

I know I will lose a portion of the signal if mounted in the attic, but that's where I really want it.

The DB2 model is 'UHF only' (which gets very good reviews), hence the inclusion of a separate VHF antenna.

I live about 15-30 miles from most broadcasts I'm looking for.

Presently I'm receiving 3 channels with rabbit ears on top of the TV in my basement, so I'm hopeful I can grab a few more with the proposed setup.

One of my biggest concerns with the proposed setup is 'ghosting' potential. Should that be a concern?

My Zipcode is 05478. I've done the antennaweb.org and tvfool.com, both very helpful. I got the reviews of antennas from hdtvantennalabs.com.

So, can I? And if so what are the splitter recommendations? I had someone tell me I can just use a splitter backwards, can you do that?.

Thanks

You can combine 2 identical UHF antennas with a 2-way splitter in reverse but you cannot point the antennas in different directions. It may work for some stations but in general you'll have terrible ghosting problems. I've read extensive posts here on people trying all sorts of ideas and nothing was reliable. The way to do it (if you don't want to use a rotor) is to run two downleads and connect them to a switch at the TV and select the antenna for the proper channel.

It is possible to do channel notching and inserting to add a channel from a different antenna but it's expensive and home setups normally don't do it.

You can combine a UHF and a VHF antenna with a UHF/VHF diplexer into one coax and use a splitter to go to your 2 TVs.

It just occurred to me that you might want to consider a rotor for just the DB-2 since it sounds like you have UHF stations in 2 directions but VHF in only one. This would be better than switching two antennas and all those additional coax runs. The DB-2 has a small turning radius compared to a VHF antenna and it might be possible to turn in your attic.


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post #3 of 24 Old 11-16-2007, 12:19 PM - Thread Starter
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Calaveras,

You've got me figured out, essentially all my UHF stations are pretty close in their direction, but the VHF is almost opposite. And yes I'm trying to avoid a rotor if possible.

You've also confirmed my ghosting worry. If I combined a UHF only antenna (facing one direction) with a UHF/VHF antenna (facing another) with splitter backwards-or a diplexer would I also get ghosting? In which case I would need to find a VHF only antenna.

Is there a difference between a diplexer and a 'backwards' splitter?

What frequency range should I be looking for in splitters (or diplexers).

Thanks
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post #4 of 24 Old 11-17-2007, 07:47 AM
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Quote:
Originally Posted by jhortonvt View Post

Calaveras,

You've got me figured out, essentially all my UHF stations are pretty close in their direction, but the VHF is almost opposite. And yes I'm trying to avoid a rotor if possible.

You've also confirmed my ghosting worry. If I combined a UHF only antenna (facing one direction) with a UHF/VHF antenna (facing another) with splitter backwards-or a diplexer would I also get ghosting? In which case I would need to find a VHF only antenna.

Is there a difference between a diplexer and a 'backwards' splitter?

What frequency range should I be looking for in splitters (or diplexers).

Thanks

Okay, so it's a little different than I guessed. You can point the VHF antenna in a different direction from the UHF antenna without a problem.

A diplexer separates VHF from UHF while a splitter doesn't. You can get a diplexer here:

http://www.starkelectronic.com/cmjoiner.htm

Use the model 0549 2nd in the list.

You should use a separate VHF antenna. A Winegard YA-1713 will probably work for you.

http://www.starkelectronic.com/wya1713.htm

Good luck.


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post #5 of 24 Old 11-17-2007, 10:30 PM
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Quote:
Originally Posted by Calaveras View Post

You can combine 2 identical UHF antennas with a 2-way splitter in reverse but you cannot point the antennas in different directions. It may work for some stations but in general you'll have terrible ghosting problems.

I agree with this, but thinking back to Antennas Direct, why do they advertise their DB8 as "multi-directional." Being able to point the two halves in different directions seems counterproductive at best.

I have a CM4228 in my attic, along with a Winegard YA-1713. I combine them with a CM7777 pre-amp, but my signals are fairly weak so I don't need to worry about overload.

In this case, the CM7777 is probably going to have problems.

If a UHF antenna is used that does not have any significant gain in the VHF bands and likewise for a VHF antenna for the UHF band, is it possible to combine them w/o filters?


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post #6 of 24 Old 11-18-2007, 05:14 AM
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Are we talking digital channels only here or are you trying to receive analog signals? If only digital, then ghosting won't be an issue, but there is some chance that you could have an unreliable signal causing drop-outs on the digital channels. My comments below refer to the digital situation.

I have two UHF antennas in my attic that are combined with a simple splitter/combiner. They are pointnig roughly 150 degrees different from each other and are both directional (though I'm sure that both probably have a fair amount of gain off the back of the antennas and one is a bow-tie which has a fairly wide angle).

My point is that you should try the simple combiner/splitter before going to the trouble of seeking out new antennas or specialized UHF/VHF combiners, etc. Combiners/splitters will set you back $2 or so at Wal-Mart, Target, Home Depot, or Radio Shack.

Since this is your attic and not your roof, the "cost" is not that high to give the simple combiner/splitter a shot. If it works, you don't have to worry about the UHF/VHF specialized combiners. If it doesn't, those are available. In a previous set-up, I used a CM pre-amp that had separate UHF/VHF inputs and isolated the frequencies. It worked out great. But, I have had not issues with my current set-up of getting UHF reception from two combined UHF antennas pointed in different directions with a simple combiner/splitter.

I think that the results are somewhat unpredictable, but this is why I suggest that experimentation is called for. The simplest solution of using the antennas that you already have and adding a component that you can pick up anywhere is very likely to work fine.

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post #7 of 24 Old 11-18-2007, 09:49 PM
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Quote:
Originally Posted by JasonATL View Post

Are we talking digital channels only here or are you trying to receive analog signals? If only digital, then ghosting won't be an issue, but there is some chance that you could have an unreliable signal causing drop-outs on the digital channels. My comments below refer to the digital situation.

I was just trying to keep it simple here. When i said ghosting I really mean multipath and multipath can be a killer for digital signals.

Quote:


I have two UHF antennas in my attic that are combined with a simple splitter/combiner. They are pointnig roughly 150 degrees different from each other and are both directional (though I'm sure that both probably have a fair amount of gain off the back of the antennas and one is a bow-tie which has a fairly wide angle).

If it works for you, great, but I've read too many horror stories where it doesn't work at all or only partially works. I can't recommend something that I know has potential problems

Quote:


My point is that you should try the simple combiner/splitter before going to the trouble of seeking out new antennas or specialized UHF/VHF combiners, etc. Combiners/splitters will set you back $2 or so at Wal-Mart, Target, Home Depot, or Radio Shack.

A diplexer is hardly a specialized item. We used them all the time when TVs had separate VHF/UHF inputs. If you use a simple splitter to combine a VHF and UHF antenna you'll introduce unnecessary loss into both plus each antenna will produce some out of phase signal on the band it's not designed for which could further degrade the signals. Spend the $9 and get a diplexer.


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post #8 of 24 Old 11-18-2007, 09:59 PM
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Quote:
Originally Posted by Falcon_77 View Post

If a UHF antenna is used that does not have any significant gain in the VHF bands and likewise for a VHF antenna for the UHF band, is it possible to combine them w/o filters?

This and the next post is making it sound like a diplexer is some exotic item. It is not. It is a very common item and is THE way to combine two antennas that cover different frequency ranges. We use them in ham radio all the time to combine 2 or even 3 antennas (the latter is a triplexer) or to combine a radio with multiple outputs for an antenna that covers muliple bands.

If you use a simple splitter/combiner for two different frequency range antennas you'll introduce 3 dB of loss + insertion loss, perhaps another .5 dB. A diplexer will only introduce insertion loss, probably less than .5 dB.


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post #9 of 24 Old 11-18-2007, 11:32 PM
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Quote:
Originally Posted by Calaveras View Post

A diplexer is hardly a specialized item. We used them all the time when TVs had separate VHF/UHF inputs. If you use a simple splitter to combine a VHF and UHF antenna you'll introduce unnecessary loss into both plus each antenna will produce some out of phase signal on the band it's not designed for which could further degrade the signals. Spend the $9 and get a diplexer.

For VHF/UHF I have seen antenna combiners. Usually, I see "diplexers" for combining satellite and OTA applications. It seems that they are the same thing, with different names.

Is something like this what you mean?

http://www.solidsignal.com/prod_disp...p?PROD=CS-7750


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post #10 of 24 Old 11-19-2007, 08:00 AM
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Quote:
Originally Posted by Falcon_77 View Post

For VHF/UHF I have seen antenna combiners. Usually, I see "diplexers" for combining satellite and OTA applications. It seems that they are the same thing, with different names.

Is something like this what you mean?

http://www.solidsignal.com/prod_disp...p?PROD=CS-7750

Yes. "Diplexer" is just generic term for a device the splits/combines two frequency bands. Ususally there is a low pass filter and a high pass filter in the device. Diplexers are used in many RF applications and are not specific to satellite/OTA or VHF/UHF.


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post #11 of 24 Old 11-19-2007, 08:19 AM
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you would use a cm0549 type unit to combine/split different bands. they make units to do a variety of things.

tv/vhf-fm
vhf/uhf
hi band vhf/low band vhf
hi band uhf/lowband Uhf

since the bands are different each band is isolated with no interference and with a minimal insertion loss of apprx. .5 db


to combine similar antennas, a standard splitter is used. since the channels will overlap there will be some interference. the insertion loss would be in the normal range of about 3.5 db

the interferce between antennas depends on several variables. these variables and how they affect reception is tough to determine until you actually experiment.

for 2 uhf and 1 vhf antenna you would need

standard splitter/combiner to combine the 2 uhf antennas and a cm 0549 to combine the 2 uhf antennas with the vhf antenna.

I would first start with uhf and try for an acceptable compromise the add the vhf with the cm0549 to see what happens.

you can experiment with aim with the 2 uhf antennas to find a sweet spot. only issue...my choice would not have been the 2 db-2s given your conditions. but give it a try.

green - uhf WFFF 44 FOX BURLINGTON VT 255° 32.8 44
green - uhf WWBI-LP 27 ION PLATTSBURGH NY 279° 25.6 27
green - vhf WPTZ 5 NBC NORTH POLE NY 255° 32.8 5
green - uhf WCFE 57 PBS PLATTSBURGH NY 274° 39.5 57
* lt green - uhf WCFE-DT 57.1 PBS PLATTSBURGH NY 274° 39.5 38
blue - uhf W55AI 55 ABC LAKE PLACID NY 246° 56.9 55
blue - vhf WCAX 3 CBS BURLINGTON VT 160° 23.7 3
violet - uhf WVNY 22 ABC BURLINGTON VT 159° 23.7 22
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post #12 of 24 Old 11-19-2007, 05:31 PM
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Quote:
Originally Posted by Calaveras View Post

This and the next post is making it sound like a diplexer is some exotic item. It is not. It is a very common item and is THE way to combine two antennas that cover different frequency ranges. We use them in ham radio all the time to combine 2 or even 3 antennas (the latter is a triplexer) or to combine a radio with multiple outputs for an antenna that covers muliple bands.

If you use a simple splitter/combiner for two different frequency range antennas you'll introduce 3 dB of loss + insertion loss, perhaps another .5 dB. A diplexer will only introduce insertion loss, probably less than .5 dB.

If you define exotic to mean that I can't get it at most Wal-Mart, Home Depot, Best Buy, or even Radio Shack, then yes, exotic might fit. But those are your words. I don't disagree that the "diplexers" are available and from good places. I certainly endorse ordering from Solid Signal. I've had very good experience with them -- particularly with specialized UHF/VHF antennas and combiners.

Calaveras, there is no need to knock a suggestion just because it MIGHT not work unless it somehow appeared to mislead someone. If you want us to all admit you probably know more because of your ham radio experience, I'll stipulate it here. If you want a monopoly on providing helpful suggestions (especially if that might save someone a few days in waiting on something to arrive mail-order when they could have tried something immediately that might or is even likely to work), look elsewhere.

In many cases, a 15db gain antenna picks up more useable signal than a 10db gain antenna. But, if the signal is reliable with the 10db gain, why argue the point that 15db is better?

There is no "THE" way to do this. There are ways that work, and ways that don't -- and some ways that work in some situations, but not in others. Thus, "THE" way for the OP to combine antennas is THE way that works for him/her. THE way for me, is the solution in which I didn't have to order a combiner - I just used the plain ole splitter/combiner that I had laying around. This might even work for the OP.

-Jason
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post #13 of 24 Old 11-19-2007, 07:34 PM - Thread Starter
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Well I'm starting to think I should adopt the K.I.S.S. principle and just go with one antenna. Any suggestions for someone in a rural area trying to suck every bit of 20-60 mile away signal out of the air (from inside an attic)?

Rick,
You seem to be familiar with this regions lay of the land, and you were hesitant on the DB-2, what do you suggest?
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post #14 of 24 Old 11-20-2007, 08:32 AM
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Quote:
Originally Posted by JasonATL View Post

If you define exotic to mean that I can't get it at most Wal-Mart, Home Depot, Best Buy, or even Radio Shack, then yes, exotic might fit. But those are your words. I don't disagree that the "diplexers" are available and from good places. I certainly endorse ordering from Solid Signal. I've had very good experience with them -- particularly with specialized UHF/VHF antennas and combiners.

Calaveras, there is no need to knock a suggestion just because it MIGHT not work unless it somehow appeared to mislead someone. If you want us to all admit you probably know more because of your ham radio experience, I'll stipulate it here. If you want a monopoly on providing helpful suggestions (especially if that might save someone a few days in waiting on something to arrive mail-order when they could have tried something immediately that might or is even likely to work), look elsewhere.

In many cases, a 15db gain antenna picks up more useable signal than a 10db gain antenna. But, if the signal is reliable with the 10db gain, why argue the point that 15db is better?

There is no "THE" way to do this. There are ways that work, and ways that don't -- and some ways that work in some situations, but not in others. Thus, "THE" way for the OP to combine antennas is THE way that works for him/her. THE way for me, is the solution in which I didn't have to order a combiner - I just used the plain ole splitter/combiner that I had laying around. This might even work for the OP.

I shouldn't waste my time answering posts like this. I've been doing this since 1970. I know what I'm talking about. You wouldn't say what you did if you understood the technical reasons why you should use a diplexer to combine two antennas of different frequency ranges. It is THE way to do it. Please reread my post above explaining why. Rick0725 recommended the same device I did.

You are simply wrong when you say there is no "THE" way to do it. There are correct ways to engineer an antenna system. The correct way is the way that will work for everyone if it is possible in their situation. Poorly engineered systems may work in some situations but won't work in many others. If I say use a diplexer, it is because that device will properly do the job. I don't say use a simple splitter because it will fail to work in many situations.

Flame away if you will but I'm not answering any more of these posts.


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post #15 of 24 Old 12-20-2007, 07:15 PM
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I have a similar situation with the exception that I don't care about VHF. I am only concerned with UHF. About half my potential channels are due west, the other half are from the southeast (about 120 degrees difference). As the two antennas are operating in the same frequency range would a reversed splitter be the way to go?
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post #16 of 24 Old 12-20-2007, 07:27 PM
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It's probably not the ideal solution, but it may work. You won't know until you try - that's why we advocate starting cheap and work your way up until you find a solution that works. What have you got to lose in trying the simple combiner - 5 minutes and a couple bucks ? Seems worth a try to me - and if it works you're golden.

You CAN put antennas on your owned and/or controlled property...

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post #17 of 24 Old 12-21-2007, 08:18 PM
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Quote:
Originally Posted by jhortonvt View Post

What I would like to do is mount 2 of the 'Antennas Direct DB2' models, and a VHF antenna in my attic. Each facing in in a different direction so as to optimize signal. Then I'd want to combine these 3 signals to 2 coax cables. One cable runs directly to the main TV, the other runs to the utility room to be split to the other potential TV's in the house.

I know I will lose a portion of the signal if mounted in the attic, but that's where I really want it.

The DB2 model is 'UHF only' (which gets very good reviews), hence the inclusion of a separate VHF antenna.

I live about 15-30 miles from most broadcasts I'm looking for.

Presently I'm receiving 3 channels with rabbit ears on top of the TV in my basement, so I'm hopeful I can grab a few more with the proposed setup.

One of my biggest concerns with the proposed setup is 'ghosting' potential. Should that be a concern?

My Zipcode is 05478. I've done the antennaweb.org and tvfool.com, both very helpful. I got the reviews of antennas from hdtvantennalabs.com.

So, can I? And if so what are the splitter recommendations? I had someone tell me I can just use a splitter backwards, can you do that?.

Thanks

Hello, you might want to use a UHF VHF Signal Joiner (UVSJ) that allows separate antenna signals to be combined to one cable. I am 38 miles from the station towers with a DIY DB4 and a Y5-2-6 with a Pico pre-amp for my VHF, in my attic 60' to my HDTV $100 or less my cost.
LL
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post #18 of 24 Old 12-24-2007, 01:39 PM
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Although I read this board regularly I have never posted. But I was taken a little aback by Calaveras' tone and wanted to add a thought or two. First, I too am a ham radio operator and have been so since the early 1960's. Further, I used to do quite a bit of VHF and UHF antenna development and test, primarily for two way communications. In short, I might have wrestled with an antenna problem once.

That being said, I strongly advocate trying the simple cheap route first. It may well work and may well save time and money. Diplexers for these kinds of applications only became readily available after about 1970. Prior to that we (amateurs and homeowners) used a variety of methods to couple stacked antennas. For reception-only purposes we would try almost anything for the quick and dirty, including plain resistive splitters. This HDTV application is receive-only so it's still worth a try. It's a bit of a black art dependent upon so many variables and so location-dependent that sometimes the try-and-see method is the only way. If you are into the technical aspects of antennas, you could estimate a mid-frequency point, calculate the wavelength in inches, and then work with feedlines to a splitter that are multiples of a quarter wavelength. But why bother? Try it first and see if it works. You still have the option of buying a diplexer if it doesn't.

Just food for thought.

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post #19 of 24 Old 12-24-2007, 05:16 PM
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I pay about a dollar each for diplexers labeled UVSJ that have insertion losses of about .5 dB and out-of-band rejection of about 30 dB, versus thirty cents each for hybrid splitter/combiners with about 3.5 dB of insertion loss and no out-of-band rejection. You may have to pay a couple of dollars more for either, buying them in single quantity.

Everybody combining a UHF and VHF antenna should use a UVSJ, whether their installation works without one or not. Mixed digital signals, unlike mixed analog signals, have avalanche failure symptoms, meaning that even if you observe "perfect" reception without one, you don't have any reliable way of knowing how close you are to experiencing a disaster. For a few bucks, you gain 3 dB in signal strength and improve the out-of-band rejection by 30 dB. That is enough reason to use one.
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post #20 of 24 Old 12-29-2007, 06:56 AM
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Quote:
Originally Posted by AntAltMike View Post

I pay about a dollar each for diplexers labeled UVSJ that have insertion losses of about .5 dB and out-of-band rejection of about 30 dB, versus thirty cents each for hybrid splitter/combiners with about 3.5 dB of insertion loss and no out-of-band rejection. You may have to pay a couple of dollars more for either, buying them in single quantity.

Everybody combining a UHF and VHF antenna should use a UVSJ, whether their installation works without one or not. Mixed digital signals, unlike mixed analog signals, have avalanche failure symptoms, meaning that even if you observe "perfect" reception without one, you don't have any reliable way of knowing how close you are to experiencing a disaster. For a few bucks, you gain 3 dB in signal strength and improve the out-of-band rejection by 30 dB. That is enough reason to use one.



I agree, the UVSJ allows clean insertion and separation of VHF and UHF bands and is inexpensive to boot.

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post #21 of 24 Old 12-29-2007, 09:08 AM
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Quote:
Originally Posted by Rick0725 View Post

pico was formed here in the syracuse area (liverpool ny) had a warehouse a few miles from my home.

http://www.picomacom.com/specs/pico/C/C24.pdf

what is a source for those wholesale. I saw a few sites at about $1 but not familiar with the company and am hessitant

The UVSJ doesn't have to be from Pico I got mine off Ebay (Digital for Cheap has them now). If you Google UVSJ you should find a good price. That Pico pre-amp MCM 201T is a bargain at Basshome.com under CCTV. Mine has less noise than advertised.

OK, I'M BACK
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post #22 of 24 Old 12-29-2007, 10:14 AM
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Any commercial parts distributors who sells in large lots will price them or similar products similarly, but most such distributors have minimum order amounts of $50 to $100, and most require the customer to establish that he is a dealer/reseller.

When you Google and find sellers offering them at under $1.00 in single quantities, just remember that if that is all you are buying, you will probably pay another $5.00 or so for shipping and handling, so paying $3 for one, if it is shipped along with something purchased from the same seller at the same time, will wind up costing you less than paying a dollar for one if it is purchased and shipped by itself.
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post #23 of 24 Old 01-10-2008, 02:55 PM
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Originally Posted by AntAltMike View Post

Everybody combining a UHF and VHF antenna should use a UVSJ, whether their installation works without one or not. Mixed digital signals, unlike mixed analog signals, have avalanche failure symptoms, meaning that even if you observe "perfect" reception without one, you don't have any reliable way of knowing how close you are to experiencing a disaster. For a few bucks, you gain 3 dB in signal strength and improve the out-of-band rejection by 30 dB. That is enough reason to use one.

I have fairly weak signals with my current antenna and plan to install a CM4228 and Winegard YA-1713. I may also use a CM7777 pre-amp. Is it necessary to use a UVSJ if also using the CM7777? Seems unnecessary since the CM7777 will handle the separate VHF/UHF feeds. But I am not an expert :-) Thanks.
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post #24 of 24 Old 01-10-2008, 04:53 PM
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Originally Posted by vulture99 View Post

I have fairly weak signals with my current antenna and plan to install a CM4228 and Winegard YA-1713. I may also use a CM7777 pre-amp. Is it necessary to use a UVSJ if also using the CM7777? Seems unnecessary since the CM7777 will handle the separate VHF/UHF feeds. But I am not an expert :-) Thanks.


Your thought is correct "Seems unnecessary since the CM7777 will handle the separate VHF/UHF feeds."

You will not need a UVSJ with the CM7777.
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