The Official AVS Antenna and Related Hardware Topic! - Page 56

I don't suppose one could connect 2 "outdoor balun kits" to the 4228 and just run two lines off it as one would do a dish?

Probably a stupid question, but in my case that could give me two "straight" runs from the antenna. I could just buy another CM7777. One for the house, one for the guest house.

j_buckingham80, thanks for posting that about reception changes.

I'm not sure I buy that. First off, trees are not nearly as good at reflecting UHF as a hard surface like a building. Secondly, large flat surfaces can create a reflection with a coherent wavefront that would appear to a receiver like a strong signal that could be locked on to. But a stand of trees would create a multitude of weak signals of all differing phases. This would look to the receiver like background noise which is more easily rejected than a single strong reflected signal that is out of phase with the main line-of-sight signal. So I think trees can *partially block* signals but I seriously doubt they can create a reflection that any receiver could lock on to or be seriously bothered by.

At only 10 miles you may actually have TOO MUCH signal. The 2160 is also not highly directional so you could be getting a lot of multipath. Dropouts and bouncing signal levels are often an indication of strong multipath. The first thing I would try is the Rat Shack variable attenuator since it is cheap and easy to put inline at your receiver. The next step is relocating and re-aiming your antenna. Changes as small as 6" or 5 degrees can have a big effect. If that fails you may want to consider a different antenna. The HD Tivo is not known for its fantastic tuner so that is not helping you. Shorter cable runs are always better than longer ones. Cut out whatever you can. If you run the 2160 direct to the Tivo do you get an change in reception?

Long distance reception (i.e. no line-of-sight) does seem to benefit from nighttime conditions. I find that nights are almost always better than days, and the good "daytimes" are few and far between. I've heard dozens of theories about this, but I've come to the conclusion that wind and sun are the two biggest factors.

When it is windy, long-distance reception suffers during the day. When it is calm, reception is better.

The higher the sun is in the sky, the worse the reception is. Thus, you should expect summertime reception to be far worse than winter.

I've also found that snow cover improves reception dramatically. It probably increases ground bounce.

I'd definitely recommend a CM7777 preamplifier for your situation. It shouldn't negatively impact the Baltimore stations (over 30 miles away, according to Antennaweb) and it should positively impact D.C. stations. It's impossible to say how much improvement you'll get, and not all the D.C. stations are on the same tower, so you might get into aiming problems (and I strongly advise against a rotor with the 4228) at that distance. Close in, pointing the antenna a little off doesn't really hurt you. At long distances, just a few degrees can make the difference between getting a rock-solid signal and getting nothing.

You could, but the impact would be the same as a splitter.

If you're willing to put up two antennas, that would be the better route, IMO.

quarque-
Thanks for the input. After doing more checking last night, I think it has to do with my HD Tivo box. The dropouts seem worse on taped materials versus live TV, and there seem to be a lot of issues with the HR10 250. I figured out how to check my signal strength and I am getting around 90 for my locals. I will try some of your suggestions though. Thanks.

If your signal levels are steady for very long periods of time then the Tivo is most likely the culprit. Sounds like the Tivo hiccups during recording. Other HD recorders have had similar issues when trying to do more than one thing at a time (not enough horsepower/speed in the hardware).

I have been using the Winegard 8 bay for several weeks. I was having problems with a staion on a higher UHF frequency (51). I read that this particular antenna is not good on higher UHF frequencies (above 50). Since I will be having a channel coming on the air at 55 in a month or so I decided to try the AntennasDirect 43XG (corner reflector yagi). I installed the antenna this morning. I had checked my signal strength with the old antenna prior to putting up the 43XG. After installation the signal strength on 51 was rock solid (it fluctuated wildly with the Winegard). There was some improvement in signal strength on my other channels. The only thing I changed was the antenna. Everything else (pre-amp, cabling, antenna heigth) stayed the same. Whether the 43XG is better at multipath or whatever, in my situation, it does a much better job than the Winegard.
I realize that due to the many variables that affect antenna performance, my results can't be extrapolated to someone else's situation but I am very happy with the antenna.

Do you mean the 43XG? I searched their site and couldn't find any antenna with an MX designation.

I'm sure the 43XG is a better performer on higher channel numbers than the PR-8800. And if the corner reflector on the 43XG is as good as the one on the 91XG, it's a solid performer on the lower channels, too.

Yes, it is the 43XG. On the shipping invoice the SKU # is listed as UE-MX43. That's what I was looking at when I typed my post. I didn't go with the 91XG becuase I thought that would be overkill in my situation (even the
medium range yagi would probably work). It appears to be a better perfomer for me even in the lower ranges (consistently better and on one channel-27-significantly better performance). For the few hours I've had the antenna up I am very happy with it.

I put my antenna up today on the house and have decide just to go with the two antenna idea so I'll also have one for the guest house. My reception didn't improve all that much, about the same as at the other location even though it's much higher. When I try to add a splitter with it being such a long run I lose channels completely. Perhaps if it was a shorter run it'd be okay to split it but not in my case.

So... sometime next week I'll add another antenna. Kind of disappointing.

OK gang, I need some advice here. Due to terrain in my section of Nashville, I have not been able to pick up all the stations I'd like to. In fact, all I can get is ABC, PBS and sometimes NBC. After talking with Voom, they are going to send out a team to install a different antenna on my roof. I will pay for the antenna, boom and mounting equipment and Voom will pick up the install charge.

I need advice on just what antenna to try next. Given the gain problems I have here, here's what I'm thinking the short list is including gain measurements from either manufacturers data or SolidSignal:

Channelmaster:
4248 8-bay bowtie (I've tried this before), 10.8 db max
3023 Yagi, 11.5 db max

Wineguard:
HD9095P Yagi, 14.2 db (ch 14), 16 db (ch 32), 15.5 db (ch 50) 12.2 db (ch 69)
PR8800 8-bay bowtie, 10.7 db (ch 14), 12 db (ch 32), 11 db (ch 50) 12.5 db (ch 69)

AntennasDirect:
91XG Yagi, 16.7 db max
DB8 8-bay bowtie, 15.8 db max


Since one of my problem channels is the local NBC affiliate at VHF-10, the 8 bays would have an advantage of bringing in an upper VHF signal. But it appears the Yagis rule having the ability to squeeze out more signal from a bad situation. And are ChannelMaster antennas really behind the curve as opposed to some of these other designs?

All of the problem stations are fortunately on the the same vector so I don't think I'll need a rotor. The stations are on UHF channels 15, 21, 23 and 56, as well as VHF 10 I mentioned earlier. The VHF channel is 6 miles away, all others are 16 miles away.

And yes, I'm already using a pre-amp (CM7777). I'm noticing some loss between the multiswitch that was installed (Wineguard) some of my rooms that is preventing me from seeing the weak NBC affiliate on two of my three televisions. Do I need a indoor distribution amps to boost the signal or another tactic? Right now, the power module for the 7777 is sitting right before the multiswitch in the chain in my garage.

I can speak from experience that the 91XG does an excellent job on VHF channel 10. I receive a perfect picture from KTTC, and they're over 20 miles away. I do use a preamp (19db VHF gain), but I suspect it isn't doing much to boost the picture.

I haven't personally tried the 4228, but I know the 4248 was an underperformer for me. The 91XG is by far the best antenna I've tried.

I'd give the 91XG a try. I think it might impress you. Since you're already trying a second antenna, try something that might be better (a different design family altogether) and see if it makes a difference. AntennasDirect has a liberal return policy if you find the 4228 is a better antenna. Also, you don't mention a preamplifier, but I assume you used one with that monstrous cable run?

OK, I'll order the 91XG. Thanks guys.

Yeah, I'm using the CM7777 amp. YOu know, I was just thinking the same thing, that I should order the 91XG and give that a try. Especially since I'm going to end up with 2 antennas anyway. I could also put a rotor on the 91XG which I didn't do with the 4228.

Today was kind of a letdown after going to all that trouble to roofmount it. It's at least 35' high now since the mast is 10'. But maybe the 91XG will improve things some more.

At least I'm getting Fox and WB all the time now, whereas before I couldn't get them at all. CBS will come in sporadically but keeps breaking up. I'm assuming that NBC and CBS will be okay again tonight at least.

I guess if I can watch The Tonight Show in HD then the effort was worth it.

I'm wondering why adding a short cable to the splitter doesn't make my channels go out, but adding a long one (150') makes them go out immediately. I added the short cable, like 10' or so, just to experiment and it didn't affect reception, but simply adding the long cable to the splitter makes all my channels go out.

I suppose I could at least get OTA in my upstairs bedroom using the same antenna since it would be a very short run, but the long run is out of the question.

I'm off to order the 91XG.

Just a quick disclaimer, I'm no antenna guru, but hey...FWIW, height's not necessarily as useful on UHF as it would be on VHF, if anything, it might be worth attempting to adjust the antenna up on down along the mast to see if a particular height is better than another.

http://www.hdtvprimer.com/ANTENNAS/siting.html

If you go here and read some of the issues related to site mounting, you can see how complex (especially for UHF) it becomes.

I have a Channel master amp 7777 and found this amp and was wondering how much it would improve reception, if any over the 7777 model. http://www.researchcomms.com/hdtv.html It has a UHF NOISE FIGURE UHF 0.4 dB. UHF 20 db GAIN vs the Channel master 7777 UHF NOISE FIGURE 2.0 dB UHF Gain: 26 dB

Send "cpcat" a PM...he has one that's for sale.Should be the very best preamp money can buy.

How much better reception do you think it will make. I did gave him a PM.


Thank you

Currently, I am using the 4228 and 7777. The antenna is mounted on the roof ~ 35 feet above ground. Generally, the reception is decent. But I am noticing a few things. The channels I am trying to receive are 17,25,47, and 54.

1. On overcast days the reception is better.
2. The reception is better in the evenings/night and early morning.
3. On sunny days, late morning and afternoon channels 47 and 54 become very difficult to receive.

Q: Does anyone have any experience in ganging two 4228's ? Would this improve this situation ?

I was thinking of purchasing either a 91XG or DAT75 to see if it were any better. If anyone has a DAT75 for sale please let me know.

cjhrph@yahoo.com

For the Pre-Amp with a noise figure of .4...Effectively, you are getting back 1.6 dB of Signal from your antenna. Signal that you normally lose. Theoretically, by cutting out that 1.6 dB of noise you are increasing your gain by 1.6dB or about 40%.

I believe the gain remains the same but the s/n ratio improves by 40% - not quite the same thing. You're not getting 40% more signal just 40% less noise mixed in with the same level of signal. If 0.4 is a real number (not advertising dept. #) then it is very impressive.

Hello all,

I have two channels I'd like to get that are consistently just below
signal acquisition levels on my tuner. The CM 4228 UHF antenna
is hooked up to the CM 7777 preamp, then 75' down the cable
to the powered part of the preamp, then another 15' to my TV.

Question: would replacing the RG-6 quad shielded length of cable with
RG-11 get me any improvement, or does the 7777 adjust the power
so that you do get an effective 26 dB gain out of the back end no
matter what? I can't move the antenna.

Actually, once you're beyond line-of-sight, this is blatently false. VHF "bends" much more readily than UHF. Thus, it is reasonable to get VHF reception from 100 miles away over average terrain. UHF is pretty much hard to do after 60 miles. (Assuming normal broadcast antenna height.) I had an antenna on my roof (about 20') and then switched to a 54' tower (and I'm married - I know, I know. Lucky guy...) Reception on UHF improved dramatically - I received UHF stations I'd never seen before. VHF improved, but not so much.

There was a guy in California who tried 2 and 4 4228s in a stack. He found 2 were better than 1, but 4 wasn't much better at all and the wind load became a major factor.

I'd strongly advise the 91XG. It may not be better than the 4228 in all situations, but it isn't nearly so heavy, doesn't have the same windload, and is a different style antenna. Where yagis have failed, bowties have worked, and vice versa.

Experts have told me that if you use a preamp, QS RG-6 is just as good as RG-11.

Sreg- No doubt height is going to help if you're trying to get around the curvature of the Earth. But in the average installation (which granted Chris is not) it doesn't take much to get an UHF antenna 4 wavelengths off the ground. I agree height is much more useful in situations like Chris's to clear obstructions, the Earth being his principal one. (basically extending his horizon) But, how much height it would take to do that is a different story. It did look like though, some of the stations he was attempting to pull in were VHF stations, so height would probably help anyways.

My more point was, that on a 10' mast, it might be worth his while to see if moving his antenna up and down along the mast might help, it's unlikely, but it's hard to know ahead of time. Also, he may be fortunate enough to be on a ridge or something similar so that his horizon is already substantially distant, in which case he might be getting reflections that reduce his signal. His day reception already significantly varies from his night reception, so it does appear that ground reflections may be having some influence.

I know folks get that glazed over look when I break out the math, but it's
the only way to precisely answer this question.

The noise temperature Tn of two amplifiers in cascade is the noise
temperature of the first plus the noise temperature of the second
divided by the gain of the first:

Tn = T1 + T2/G1.

To convert Noise Figure(f) to noise temperature (Tn):

Tn = 290(10^(f/10) - 1)

So a 2.0 dB preamp has a noise temperature of 169.6K

Let's say that the Noise Figure of your receiver is 10 dB and your RG6 cable
loss is 5.0 dB for a total Noise Figure of 15.0 dB. The receiver noise
temperature is 8880K.

Then the system noise temperature is 169.6 + 8880/400 (26 dB) = 191.8K

To convert from noise temperature back to Noise Figure:

NF = 10 log(1 + Tn/290)

So the system Noise Figure is 2.2 dB. The gain of the preamp "washes out"
the noise of the receiver and connecting coax.

Now let's plug in a different value of coax loss. Your rich uncle buys you
some 7/8" Heliax ($6 a foot) and your coax loss goes down to 1.0 dB,
making your receiver noise figure 11.0 dB or 3361K.

169.6 + 3361/400 = 178K or 2.08 dB

Your rich uncle's $600 was the wrong place to put the money since it only
buys you an undetectable 0.12 dB of signal to noise ratio. You should have
spent it on a taller tower or mast, a bigger antenna or a better preamp
(in that order).

Now for something counter-intuitive. Let's say the gain of the preamp is
13 dB instead of 26 dB at the same 2.0 dB Noise Figure. Then the system
noise temperature (with the 5.0 dB loss RG-6) is 169.6 + 8880/20 (13 dB) =
613.6K or a system Noise Figure of 4.9 dB. In this case, 13 dB less preamp
gain only causes the loss of 2.7 dB of signal to noise ratio.

Ron