Will a pre-amp help?

QEG2

Hi everyone, like the title says, will a mast mounted pre-amp help me?
The location - Baltimore, MD
The report - w w.tvfool.c0m/?option=com_wrapper&Itemid=29&q=id%3dbc27a961807b5 1 (sorry, I can't make it a real link untill I have 5 posts)

The antenna setup -
2 Antennacraft MXU47 UHF corner reflectors side-by-side (about 6 ft apart) about 30 ft up (and a 10M ham beam at about 35 ft.) on a CD44 rotor pointed at Wash,DC. The 2 are combined then sent down to a Winegard BC-782 distribution amp (4 output) in the basement. All coax is quad-shield.

Thanks

The reception (w/o moving the rotor) -
Baltimore chs - 38,11,13,41,46,40,29 (all of them)
Annapolis ch - 42
Wash,DC chs - 48,36,9,35,33,50,27 (all but ch 7)
northern VA chs - 15,34,24

The problem -
There is (of course) drop out on some depending on the weather (even local chs 11 and 13), that I'd like to eliminate. Would a mast mounted per-amp (right after the combiner) help?

I stuck a real small UHF corner reflector elsewhere on the roof pointed at Baltimore and combined them right before the distribution amp, but things got worse. I guess the loss from the combiner was too much.

JB Antennaman

You don't have to make 5 posts, all you have to do is give us the coordinates. I suck at the internet and playing games with the address to make it work, so I am just going to take a stab at it.
Where is McTubber when I need him?

2 Antennacraft MXU47 UHF corner reflectors side-by-side (about 6 ft apart) about 30 ft up (and a 10M ham beam at about 35 ft.) on a CD44 rotor pointed at Wash,DC. The 2 are combined then sent down to a Winegard BC-782 distribution amp (4 output) in the basement. All coax is quad-shield.

The Antennacraft MXU47 antenna's are the first weak link. They are not as good a performer as is one XG 91 Terrestrial Digital antenna.
Solid Signals advertisement goes as far as to say that it does not even come with a transformer. The transformer is as important as the antenna - antenna's. You can have the greatest antenna in the world and the suckiest transformer and a cheap antenna with a good antenna might out perform it. When you butt crap into your coax and then run it down to the amplifier and then try to amplify it, all that is going to come out the other end is more crap. -->

The Winegard Distribution is the next weak link. When amplifying a signal it is best to amplify what little signal you have and try to improve it as much as possible. Keeping the pre amplifier as close to the antenna as possible to lessen the amount of loss. Be it the splitter loss you have from the combiner and the wire loss from the antenna to the amplifier - which in your case could be as much as 60 or more feet. Right there you are probably loosing as much as 7 db of signal.

UHF is line of sight, if you point the antenna in the wrong direction and have a weak signal and expect a weak antenna to pick up the signal off the side or back of the antenna, you are going to experience drop outs and lock up's.

Baltimore is the 24'th largest market, you can use Rabbit Ears as a reference. http://www.rabbitears.info/market.php

WBAL is channel 11, it is only 5 Kw, and a UHF antenna does not work well for reception of VHF. Right there is strike 1

WJZ is real channel 13, and is 28.8 Kw - pretty good.

Channel 42 only has a 48 mile contour max, so if you are in their reception area, good, if not - sorry about your luck. But like you said they all come in well.

Again with Washington DC and Channel 7, if you use the wrong antenna, then you are not going to get it. It is just too far and too weak for a UHF antenna to receive that VHF signal.

Washington DC is the 11th largest market and channel 7, 8, and 9 will all require a good VHF antenna to receive.

To simplify the situation, I would either replace your existing antenna's with one Winegard 8200U or 7698P antenna and a Channel Master CM 7777 or a Winegard AP 8275 pre amplifier and only use the distribution amplifier if you have to - if the loss in the wire in the interior of the house is too much for the pre amp to compensate for.

Keep the rotor and the good wire and weather proof all terminals and make sure to use a good ground from the antenna to the ground stake for the service entrance and things should be fine.

Maybe other forum members would have some suggestions as to what other antenna combo's would work for your situation.

Just keep in mind that if your antenna is not orientated properly to receive the stations, there will be times where you will either need to turn the rotor or watch something else.

Please come back when you install your antenna and tell us how you made out.

__________________
I feel like the mayor of retard's ville..

hoopitup2000

If you are getting the weak channels 50 & 27 from DC reliably now, you're doing well & won't likely benefit from any additional amplification. A VHF-HI antenna is needed to improve the reliability of 7,9,11 & 13. The Antennacraft Y5-7-13 will likely do the trick. Combine it with your UHF antenna(s) using a UVSJ.

NonMcTubber

I hate to disappoint JB, as here I come to save the day, but I can't get the TVfool report to post either.

Beyond that, my comment is, is there a dimes worth of difference between a distribution amp or a antenna mounted preamp? Other than the fact that the preamp has less coax distance to compensate for.

In MHO, there is somewhat a myth here in assuming that if some amplification is good, more will always be better.

Other than that I suspect JB is barking up the right tree, by concentrating on getting an antenna(s) with the best signal to amplify as requirement one.

__________________
High definition is not the definition of my life.
But knowledge is power and HD does have some potential to increase content variety and choices.

IDRick

Here is the tvfool report: http://www.tvfool.com/?option=com_wr...bc27a961807b51

The OP has very strong nearby signals. A pre-amp is likely to overload under these conditions. I couldn't find any specs on the Winegard distro amp. Tigerbangs usually recommends the CM 3414 distribution amps (when 4 outputs are needed).

IDRick

Thanks for stepping in with a local's perspective Hoopitup!

QEG2

The 47's are there 2 stay, so i want to get the most from them. The splitter/combiner is from TruSpec and the coax from that is about 35 ft of quad shield to the amp/splitter. If theres a mast mount amp that would work better and I could eliminate the BC-782 and use just a 4 way splitter, that's fine

I know, that's why I'm pointing them at WDC, and am recieving local stations off the sides/back, with only minor issues. That's why I toyed around with the 3rd ant to boost the Baltimore signals to eliminate any drop out there.

Well I'm getting 9 now, and have never had 8, it's too far. 7 I realize I'd need a VHF ant for, so I can do w/o it.

.

That's a given, but so far I havent needed to turn it, as planned.
Even if 2 Balt chs (11 and 13) are VHF and the 3rd antenna is UHF, the addition of the smaller antenna pointed at Balt would work well enough on those to help negate any need to move the big one off of WashDC, if I get it wired in with out the loss.
If a mast mounted amp would work by replacing the WG BC-782amp/splitter with just a splitter, that would be OK.

QEG2

That's correct, and a concern, that another amp might make the local chs too strong, even off the back side of the ant.

JB Antennaman

Sometimes it is easier to explain a complex question to a complete moron then to try to explain a simple question to a person that thinks that they know it all.

The first thing you need to do is to move your television antenna away from your short wave antenna. Put it on a dedicated mast someplace and on a rotor and be willing to turn it to the desired direction to receive the signal at hand.

All a person can give is advice, if the op refuses to listen to logic, then there is no reason to discuss this matter further. I wouldn't use a UHF antenna to try to receive VHF, nor would I use two UHF antenna's and a rotor and then refuse to turn the rotor.

Maybe if you used some type of A/B switch it would work, but the multipath during tropo would kill as much as it would gain.

AS QEG2 has found out, what worked in the summertime when signal levels were high, doesn't always work in the winter when signal levels are low. No amplifier is going to compensate for having the antenna pointed in the wrong direction or having the wrong antenna.

__________________
I feel like the mayor of retard's ville..

IDRick

QEG2,

Which stations are having dropouts? With your setup, I would guess that the vhf channels are a potential problem area. I agree with Hoopitup2000 and suggest you mount a high vhf antenna to your antenna mast (3 to 5 ft below the MSU47's) and join it to your UHF antenna with a UVSJ.

I also wonder if you are getting the full benefit of joining your two MXU47's? For a good discussion, see:

http://www.antennahacks.com/CombinerComparison.htm
http://www.hdtvprimer.com/ANTENNAS/ganging.html

QEG2

Yes, it is the VHF chs, as well as some of the distant UHF.

I realize that trying to receive VHF on a UHF antenna is less than optimal (I was surprised to get ch 9 in W,DC), but since 95% of them are UHF, I went with UHF antennas.

As far as adding the small antenna pointed right at TV hill in Baltimore, I chose the little UHF one because I had it lying around. And if I can get those Bal VHF chs perfect say 95% of the time now (90 degrees of the side of the array), about anything pointed directly should do better.

And yes, I think that I am benefitting from the dual MXU47's, I tried a single one first. The dual's give me a wider beam spread if nothing else.
And it's not that I won't turn the antenna, if I can make small adjustments to the antenna system (different amp, splitter, etc), I might be able to eliminate the need to turn it. It was difficult to get those antennas up there, so I'd rather not make changes up there.

The mast mounted amp may not be the answer, that's why I asked.

Does everyone here get so upset when their advice isn't obeyed?

QEG2

Thanks. For the time being at least, I can't make any antenna changes; but amps, splitters, etc yes.

Tower Guy

Because the use of UHF antennas to attempt to receive VHF stations is an extremely common problem.

You need a real VHF antenna, not a preamp on your UHF scheme.

aka.Hooper

Hey Rick, I'll third the motion.
QEG2, you are using a side by side UHF rig rightfully aimed at the lower strength transmissions and hoping to get VHF off the back without turning the rotor 'cause you have multiple TV's, understood. However to hope this will work seems overly optimistic, as does using a third UHF antenna aimed for them and brought together with splitters/combiners. (That just sounds like it could introduce multipath to your nice tight beamed duo.)

I'm assuming your UHF's come in fine off the back, so the addition of a YA-1713 or such aimed also for the lower level stations @217deg should pick the stronger 11 & 13 off the back as well. If all you're looking for is the strong VHF transmission with that third antenna aimed directly you could bring it together with the UHF array with a UVSJ, but this would prohibit any chance of getting any VHF off the duo UHF's.

You currently have ~5' between your UHF antennas and your Ham, but that will end up crowded once adding a VHF. You could mount the VHF below the UHF as Rick suggests and put the Ham on it's own mast or mount the VHF antenna separately with a fixed aim. (cable lengths are irrelevant using a UVSJ.)

From what I understand, dist amps usually have a higher noise factor than a preamp. Assuming the dist amp is being used as secondary amplification, the dist amp's NF is negated by the preamp. If however it is the only amplification (as is the case here) then it's noise becomes dominant, and may become a factor (along with the additional cable length from the antenna, as you mentioned) in receiving a low level transmission.

I couldn't find any info on the OP's dist amp, so I don't know how efficient it is. Question is, if the antennas are all left at the lower transmission aim will the locals overload say a HDP-269 being received off the back? I know Rick has the answer to this.

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IDRick

Very informative reply QEG2!

Only JB gets upset. Please don't evaluate our forum based on the local curmudgeon... JB fails to understand that each person's situation is unique as well as each person has their own specific goals.

Ganging antennas gives you a maximum of +2.5 dB of received signal. Just curious, did you notice a change in signal strength when ganging antennas? It's a challenge to get the full response, kudos to you for your setup! The first link in previous post did show differences between splitters used as combiners. You may be able to get a small boost by changing splitter...

The vhf antenna your best solution for improving the vhf signals. I'd suggest giving it a try this spring. Your call though obviously...

Good luck!

Rick