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Old 20-Jan-2016, 4:38 PM   #41
shoman94
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Originally Posted by ADTech View Post
Typically, filtering is done prior to amplification to prevent the amplifier from creating distortion products with the amplifier itself.

However, in the case of the Juice, that thing is so tolerant of strong signals it will simply pass any FM signals though it (amplified, of course) without any discernible internally generated distortion. Unfortunately, that would then shift the risk of distortion to the active devices further down the chain such as tuners or any subsequent amps.

In your specific situation [emphasis added], you can readily install the tramps downstream of the Juice's power inserter and still keep any strong FM signals out of the downstream signal path. Since you're filtering post-amplification, you'll essentially need an extra trap in order to knock down the already-amplified FM signals.
Can the Juice be place in a weather tight box? I notice it does get warm. If its recommended it be outside then I'll get a smaller enclosure for just the traps.
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Old 25-Jan-2016, 1:14 PM   #42
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Moved the Juice and FM traps on the mast. FM traps are inside a weather tight box. I did move the VHF dipole from being clipped to the upper reflector to just under it and attached it to the mast so I can aim it. Now I can't get a lock on channel 10 anymore but I gained channel 11. I think the reflector was helping with that VHF channel when it was clipped to the reflector.

@ADTECH; I was wondering if you could provide me with a couple things....
What would the gain graph look like if I removed the reflectors or even just one reflector?

What would the gain graph look like if I rotated the C4V 90 degrees so they were aligned vertically vs horizontal?

Thanks!
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Old 25-Jan-2016, 1:52 PM   #43
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The Juice is already weatherproof. Just don't mount it upside down.

With both reflectors removed, the gain would drop by 2-3 dB across the UHF band. Of course, the F/R ratio would drop to 0 as the antenna would then become bi-directional. I have no idea what the specific effects might be with a single reflector removed. As far as I know, that has never been modeled and I know I haven't tested it.

Rotating the antenna is not recommended unless you're in an area that uses vertically polarized broadcast signals as there's approximately 20 dB cross-polarization rejection. We've made the current production models capable of this rotation as we've been contemplating an entry into the UK market. Please note, there are some TV stations in North America that utilize circular or elliptical polarization so those stations would not be affected by the rotation of the antenna.

It is often to experiment wit the physical location of the VHF dipole. Moving it a few inches or a foot or so can make or break reception, depending on the immediate peaks and nulls present in any signal in any given point in space. Patience is a virtue.
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Old 25-Jan-2016, 2:11 PM   #44
shoman94
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Originally Posted by ADTech View Post
The Juice is already weatherproof. Just don't mount it upside down.

With both reflectors removed, the gain would drop by 2-3 dB across the UHF band. Of course, the F/R ratio would drop to 0 as the antenna would then become bi-directional. I have no idea what the specific effects might be with a single reflector removed. As far as I know, that has never been modeled and I know I haven't tested it.

Rotating the antenna is not recommended unless you're in an area that uses vertically polarized broadcast signals as there's approximately 20 dB cross-polarization rejection. We've made the current production models capable of this rotation as we've been contemplating an entry into the UK market. Please note, there are some TV stations in North America that utilize circular or elliptical polarization so those stations would not be affected by the rotation of the antenna.

It is often to experiment wit the physical location of the VHF dipole. Moving it a few inches or a foot or so can make or break reception, depending on the immediate peaks and nulls present in any signal in any given point in space. Patience is a virtue.
Well I found it odd with channel 10 because it is mounted on the same tower as Fox (channel 23) Plus if I remember correctly I was getting channel 10 and channel 8 even with the Dipoles not hooked up! I thought that was strange.

So removing the reflectors would effectively give me the same gain as a C2V? With the C2V I wasn't able to catch FOX (channel 23) reliably. The C4V gave me about 20-30% greater signal strength. Does it change what the graph looks like much besides the DB loss on the forward side?

I also wondered why the C4V wasn't vertical stacked like the DB4E?
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Old 25-Jan-2016, 6:10 PM   #45
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Well I found it odd with channel 10 because it is mounted on the same tower as Fox (channel 23)
Doesn't matter. Each frequency will have it's own signal path which can be filled with minor anomalies which, when the signal finally arrives at any given random point in space (where you happened to put the reception device), can result in the signal getting pushed off the edge of the "digital cliff". When using a simple dipole, the issue can be aggravated by the dipole's reception pattern which can easily admit either reflections or other interfering signals. It is a mistake to assume that all signals from any given area or tower, even from the same antenna on a tower (there are transmitting antennas which broadcast multiple channels simultaneously) will arrive at any give point is space (where you planted the antenna, for example) with uniformity, there are always differences which are frequency-specific and those differences are the reason we put in big red letters at the top of every installation sheet the phrase "Before attaching the antenna to any surface, TEST RECEPTION in that area." Such peaks and nulls on UHF frequencies can be as little as 6-12 inches apart.

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So removing the reflectors would effectively give me the same gain as a C2V?
Peak boresite gain will drop as indicated. The reception patterns will also change, especially side lobes, but I've never seen any simulations that show it, I just know it will happen. My guess is that the pattern of a reflector-less C4 would look something like a typical bidirectional antenna with observable side lobes fore and aft.

Quote:
I also wondered why the C4V wasn't vertical stacked like the DB4E?
It depends on the design goal. Stacking two double loops vertically would indeed increase the peak boresite gain by about the same as stacking them horizontally while maintaining the ~70 HPBW instead of halving the HPBW as does the implemented design.. However, you would have to have a much longer mast to accommodate the vertical stack and this particular products was designed with retail (B&M) store shelf space in mind. It would also make assembly more complicated.
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Last edited by ADTech; 25-Jan-2016 at 7:25 PM.
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Old 25-Jan-2016, 7:47 PM   #46
shoman94
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Doesn't matter. Each frequency will have it's own signal path which can be filled with minor anomalies which, when the signal finally arrives at any given random point in space (where you happened to put the reception device), can result in the signal getting pushed off the edge of the "digital cliff". When using a simple dipole, the issue can be aggravated by the dipole's reception pattern which can easily admit either reflections or other interfering signals. It is a mistake to assume that all signals from any given area or tower, even from the same antenna on a tower (there are transmitting antennas which broadcast multiple channels simultaneously) will arrive at any give point is space (where you planted the antenna, for example) with uniformity, there are always differences which are frequency-specific and those differences are the reason we put in big red letters at the top of every installation sheet the phrase "Before attaching the antenna to any surface, TEST RECEPTION in that area." Such peaks and nulls on UHF frequencies can be as little as 6-12 inches apart.



Peak boresite gain will drop as indicated. The reception patterns will also change, especially side lobes, but I've never seen any simulations that show it, I just know it will happen. My guess is that the pattern of a reflector-less C4 would look something like a typical bidirectional antenna with observable side lobes fore and aft.



It depends on the design goal. Stacking two double loops vertically would indeed increase the peak boresite gain by about the same as stacking them horizontally while maintaining the ~70 HPBW instead of halving the HPBW as does the implemented design.. However, you would have to have a much longer mast to accommodate the vertical stack and this particular products was designed with retail (B&M) store shelf space in mind. It would also make assembly more complicated.
Maybe I can play around with them one day to see what they do. Try the one reflector on and one off as well.... There is one channel (ION) on the back side that I see signal but its not quite strong enough to lock on. It would be interesting to see if I could gain that and not lose quality on the front side with (FOX).

One other channel on the back side I'd like is channel 9 (WMUR VHF).. I think I'd need to get a CS5 to get that but its a bit pricey for one channel that I don't need...lol.
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Old 28-Jan-2016, 11:11 PM   #47
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It depends on the design goal. Stacking two double loops vertically would indeed increase the peak boresite gain by about the same as stacking them horizontally while maintaining the ~70 HPBW instead of halving the HPBW as does the implemented design.. However, you would have to have a much longer mast to accommodate the vertical stack and this particular products was designed with retail (B&M) store shelf space in mind. It would also make assembly more complicated.
SO are you saying that if I kept the UHF elements the same orientation but stacked vertically I would end up with the same gain but keep the 70 degree HPBW? I think that would suit me based on my report!
Looking at the installation manual I think I can stack the loop elements and have the combiner bar connections on the loops facing each other and maybe this would still allow the combiner bars fit right up?
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Old 29-Jan-2016, 12:50 AM   #48
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SO are you saying that if I kept the UHF elements the same orientation but stacked vertically I would end up with the same gain but keep the 70 degree HPBW? I think that would suit me based on my report!
Yes, more or less the same.

Quote:
Looking at the installation manual I think I can stack the loop elements and have the combiner bar connections on the loops facing each other and maybe this would still allow the combiner bars fit right up?
No. You cannot do it with the C4 combiner without really messing up the engineering of the phasing bars.

You'd either have to start with two C2 antennas and make a combiner (out of coax cables and a two port splitter, for example) or, if you have a C4, use standard baluns (matching transformers) to match to the same homemade combiner.
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Last edited by ADTech; 29-Jan-2016 at 1:02 AM.
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Old 29-Jan-2016, 2:25 PM   #49
shoman94
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Yes, more or less the same.



No. You cannot do it with the C4 combiner without really messing up the engineering of the phasing bars.

You'd either have to start with two C2 antennas and make a combiner (out of coax cables and a two port splitter, for example) or, if you have a C4, use standard baluns (matching transformers) to match to the same homemade combiner.
I guess my view is a little fuzzy at the moment. I see what you're saying but I'm not sure without trying that it cannot be done with the current phase bar/combiner.
I say this because the two loop elements are the same so if you flip one of them 180 so the connections are at the bottom then place that one on top of the other so the connection face each other, the orientation for the connections should be the same for the phase bars. See my sketchy 2 min sketch of what I mean attached.

Like I said, dimensionally I don't know until I try it. Maybe you have some parts and pieces you can try?...lol

About channel 10 and 11... I think that is being picked up by the loop antennas. I haven't raised it yet but last night I tried rotating it in different positions and some matter what position I put the dipoles in, the only signal that were effected was channel 8. No matter what position I placed the dipole, the signal strength remained the same for channel 10 and 11 (32-35%).
Attached Images
File Type: png SketchC4Vert.png (8.1 KB, 208 views)

Last edited by shoman94; 29-Jan-2016 at 2:30 PM.
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Old 29-Jan-2016, 3:08 PM   #50
ADTech
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Like I said, dimensionally I don't know until I try it. Maybe you have some parts and pieces you can try?...lol
It won't work without mangling both metal and performance. Forget it.

Quote:
About channel 10 and 11... I think that is being picked up by the loop antennas.
Not if you have the VHF module installed. It rejects any VHF from the loops by at least 15-20 dB and replaces it with the VHF from the dipoles. Vice versa for UHF from the dipoles.
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Old 30-Jan-2016, 2:15 AM   #51
shoman94
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It won't work without mangling both metal and performance. Forget it.

Not if you have the VHF module installed. It rejects any VHF from the loops by at least 15-20 dB and replaces it with the VHF from the dipoles. Vice versa for UHF from the dipoles.
Vertical stacking the C4 loops didn't work. FOX was gone and WPXT and WPME were weakened.....

I raised both antennas 5 feet now and placed the dipoles on top. I'm now getting WCBB and WENH solidly.
Attached Images
File Type: jpg PHOTO_20160129_181117-1024x768.jpg (141.9 KB, 250 views)
File Type: jpg PHOTO_20160129_181039-1024x768.jpg (129.7 KB, 224 views)
File Type: jpg PHOTO_20160129_181102-1024x768.jpg (142.0 KB, 216 views)

Last edited by shoman94; 30-Jan-2016 at 2:22 AM.
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