Some Follow Up Questions

[docsuess84]

I had gotten some advice here, and I have my base set-up up and running. Here are the original threads for reference. http://forum.tvfool.com/showthread.php?t=14907
http://forum.tvfool.com/showthread.php?t=14820

Here is my current approximate plot from the previous threads. http://www.tvfool.com/?option=com_wr...d2438e744b90c9

Some of the channels are not accurate anymore. I used rabbitearsinfo in order to figure out what stations I am aiming for. http://www.rabbitears.info/search.ph...pe=dBm&height=

Even with over 350 plus feet of coax in my run I can receive most of of local stations I anticipated being able to get, and I'm not even using any type of amplification since I broke both the unit and the power supply by over tightening the connections. Anyone out there using the RCA preamp for the first time, do it by hand not with a wrench. I'm not pulling in any of the major affiliates except my VHF ABC station as they are either far away or weak signals. My questions are:

1. My antenna is an Antennacraft 5884 combined UHF/VHF and is pointed approximately 220 degrees in order to pick up all the stations I can except NBC, which is around 159. They are all UHF. Only ABC (Channel 7) is VHF, and there is a UHF alternative on the same tower. Should I just replace it with a UHF only since I don't need to try for any VHF stations, or if I replace the preamp and only amplify UHF would that work?

2. In order to try to get NBC I'm probably going to need an amplified high gain UHF antenna and point it southeast to Chico where it transmits from. Will having two UHF antennas with one pointed at 220 and one at 187 on the same mast pose a problem if I attempt to combine the signals? Can two separate UHF amplifiers be powered on a single run of coax? Do I just have two power supplies in line with each other? In my original set-up, and prior to breaking it, I had put the power supply in the pump house for my well. It reduced the distance the power had to travel back up to the antenna while still shielding it from the elements.

3. If interference was an issue and I needed to use an A/B switch would I need to use a diplexer so they can share the same long coax run from the hill to the house?

Just trying to plan ahead and make sure I'm not overthinking it all. Thanks everyone, it's great being able to watch anything, but I'm always trying to improve my set-up. Drives my wife nuts.

[ADTech]

Please include a link to your prior thread(s) plus a link to your current TVFool plot for reference.

[timgr]

Is this your report? http://www.tvfool.com/?option=com_wr...d243f318247686 I don't see anything there at 187 that isn't -25 dB NM or lower. Specifically which stations are you thinking of?

[docsuess84]

Sorry, 159 is apparently more accurate according to rabbitears. NBC has no translators in my area, just KNVN in Chico. The others are in the general vicinity that my antenna is already pointing at.

http://www.tvfool.com/?option=com_wr...d2438e744b90c9

This report is more reflective of my antennas position on the hill behind my house. It's on an approximately 18 ft mast if you account for the length cemented in the ground.

[timgr]

Have you tried pointing at 147 to see what stations you get?

Usually combining dissimilar antennas in the same band on the same wire does not work well.

If you wanted to get a DB8e, for example, you could point one panel at 225 and the other at 162, and use your 5884 for VHF reception. The DB8e might pick up KRCR 7 and KIXE 9 even though they are out of band. Or you can use a dedicated VHF-high antenna and combine the signals with a UVSJ or the RCA preamp.

[Stereocraig]

I am all for using a small wrench on coax fittings, but a certain degree of caution, must be exercised.

The main problem, lies in the failure of mfrs, to secure the F connector to the housing, as well as the circuit board.

"By hand" snugging may be adequate, but an unsecured piece of coax, may twist in the wind and eventually work itself loose.

[Flint Ridge]

I'll second the "don't wrench the RCA". One of my first I spun it using a wrench. Second one I went ever so gentle and I heard a crack. It has four tiny little legs holding it in place on the inside.

[docsuess84]

I've pointed it everywhere and nothing changes. The stations I get (the green ones) are perfect and nothing else, even if it's not pointed directly at the tower. If I can amplify my antenna enough all I'm missing is NBC. I can live with that but I'd like to try. The issue with two kinds of UHF antennas was why I was curious about using diplexers. Rather than combine signals I'm just wondering if they can share my existing coax run and then separate at a diplexer connected to an A/B button in the living room. I just wasn't sure if diplexers could carry the same type of signal from two sources. On another note, when I go to replace the preamp since my VHF signals are full strength can I plug a combined VHF/UHF into the UHF port without issue?

[timgr]

It would be fairly involved to mix the signals on the same band so they could be separated at the tuner. The digital signals are already time-multiplexed into each frequency. So you'd need to separate the two streams by frequency. That involves a frequency generator and mixer to make sidebands at a new frequency. Then one of the sidebands could be filtered from the stream at the other end and mixed down to the proper frequency for your tuner. Not impossible, but any antenna-based solution is going to be vastly cheaper, I'd think.

A simpler solution would be to filter the stream from each antenna to only pass the single channel or channels that you want - effectively making a narrow-band antenna. Then you could mix these streams on the same wire and they would not interfere. Still, it's going to be more expensive than a DB8e, for example, that could be pointed in two directions.

Yes, you can put the UHF/VHF signal into the UHF port, but only UHF will come out. The preamp filters out VHF from the UHF input, and vice-versa.

[ADTech]

Yes, you can put the UHF/VHF signal into the UHF port, but only UHF will come out. The preamp filters out VHF from the UHF input, and vice-versa.

That's the case only if the switch is set to "Separate". If the switch is set to "Combined", EVERYTHING (except 250-400 MHz) comes out unless FM if the FM trap is in.

[docsuess84]

Ok, so combining signals is definitely the easiest and cheapest way to go. If I were to add the DB8, point it in the two directions along with with an RCA amplifier, is there a way to rig my existing antenna to only do VHF? That might just solve my problem. If the DB8 was able to pick up my VHF channels that would obviously be unnecessary but just in case, how would I do that?

[ADTech]

Just set the switch to "Separate" and connect the VHF antenna to the VHF input. Yep, it's that simple.

The problem is mixing the off-axis UHF signal with the rest of the UHF signals.

[docsuess84]

That is totally simple. I was just worried about overloading the VHF since they already come in so strong without amplification. Will that be an issue?

[timgr]

Originally Posted by docsuess84

That is totally simple. I was just worried about overloading the VHF since they already come in so strong without amplification. Will that be an issue?

I'm using the Antennacraft 10G221 mast mounted preamp. It is marketed specifically for situations where there is a mix of strong local and weak distant signals. I would expect this means a larger input dynamic range, traded off against lower amplifier gain. It works fine for me, but I have not compared it to other preamps.

In theory, you could just amplify the band-limited UHF signal, and combine it with the strong VHF downstream of the amp. However, your UVSJ (combiner) would have to pass phantom power to the UHF preamp, and I don't know whether they do that or not. Seems unlikely.

[ADTech]

However, your UVSJ (combiner) would have to pass phantom power to the UHF preamp,

Our EU385CF-1S and the Radio Shack 15-2586 both offer DC Pass on the UHF port.

I was just worried about overloading the VHF since they already come in so strong without amplification. Will that be an issue?

It can be. Amplifying UHF only is the simplest work-around. If you use an amp with a separate VHF input, you'll probably have to pad down the input with some intentional attenuation.

[docsuess84]

You guys are starting to confuse me. My existing antenna does UHF and VHF. If I get a DB8 and combine the two with the preamp in separate inputs that solves my signal combining problem, converts my antenna to VHF only and amplifies my UHF but possibly overloads the VHF signals since I don't need to amplify those. That's why I'm wondering if there is a simple tweak of my existing antenna to make it a VHF only so I can then just combine that one non amplified with an amplified DB8.

[ADTech]

You have to pick a pre-amp in order to finish the exercise. Then, use one of the UVSJ devices I mentioned and feed your existing U/V antenna into the VHF input on the UVSJ.

[timgr]

Originally Posted by docsuess84

... That's why I'm wondering if there is a simple tweak of my existing antenna to make it a VHF only so I can then just combine that one non amplified with an amplified DB8.

Yes. You use a filter that passes VHF and blocks UHF. The antenna still receives UHF and VHF but the UHF frequencies are blocked by the filter.

The preamps and the UVSJ both include filters. The UHF port has a filter to block VHF, and vice-versa. No need to modify the antenna... just filter out the part of the signal that you don't want.

ADTech suggested a couple of UVSJ (UHF-VHF combiners) that will work for what you suggest.

[docsuess84]

Got it, two devices for two antennas. UVSJ for the combined antenna to filter out the UHF and to combine signals with the other and a preamp for the DB8. I remember reading on here the jumpers from separate antennas to a preamp or signal combiner need to be close to the same length. Should that be the case here?

[ADTech]

Should that be the case here?

Not needed. They can be any appropriate length as needed.

The equal length jumpers are needed only when trying to phase two identical antennas.