The Official AVS Antenna and Related Hardware Topic! - Page 396

So my DB2 arrived in the mail today, and it's definitely an improvement, but there's still a couple channels I can't pick up with the rest of the channels because the towers are at a different angle (and possibly also because one of them is a VHF channel, and the DB2 is mostly a UHF antenna... stupid ABC).

Would it be possible to get a second antenna (whether or not it's the same antenna), place it at the proper angle for the channels I'm missing, and use some splitter ("backwards") to combine the output from both antennas into one good signal? Or would noise from both antennas nullify the good channels that the other antenna is picking up? Would I be better off just getting a bigger, higher gain antenna?

Thanks again... God I want to figure this out so I can drop my freaking cable TV service already.

DB2 isn't "mostly" a UHF antenna. It is a UHF antenna. It is not a VHF antenna.

The signal from two antennas can be combined. You have to be careful how you do it. If the signals are not in phase, it can be worse with two antennas than with one. If the signals are in phase, you can just combine them and get a stronger signal to your receiver. If not, the general approach is to use one or more filters before combining the signals so that each channel will come from only one antenna.

How many degrees apart are the missing channels from the ones you are getting successfully? And what is the VHF channel?

I said "mostly" because I've seen several people say that this antenna improved their signal strength for even VHF channels. In my case, the VHF reception was about the same as before if I had the antenna at the appropriate angle -- otherwise it was worse.

I think I have to rotate the antenna about 45 degrees to get the maximum signal I can get from the missing VHF channel. It's channel 8. Strangely, though, according to AntennaWeb, this channel is at the same angle as the other channels that I'm getting.

A few of the other channels occasionally still have less-than-ideal strength, though... so a bigger antenna might serve me well I think. Would it be feasible to get a DB8 and rotate one or two of the four pieces towards the tower of the missing channels?

The only thing I can suggest is check as many directions of aim as you have the patience for because you might find a bearing that gives you everything you want.

Try attaching a couple of 36 inch rods, horizontally and centered, to the DB2s reflector. If channel 8 is fairly strong, that may do the trick for you.

If RF 8 is the only VHF frequency you're after, get a dedicated VHF-high antenna (pointed at RF8) and combine that with your UHF. You'll need a UVSJ to do the trick.

How important is the other UHF frequency?

Isn't the wavelength of Ch 8 30 inches so wouldn't each rod need only be 15 inches? You're the expert so I'm just confused.

This channel is ABC, so it's pretty important for me to pick it up. ABC also has a couple other channels on this band that I want (weather channel, traffic channel). Any recommendations on a good VHF antenna? And/or a good VHF-UHF antenna?

I just realized that I might need to upgrade to the DB8 (or at least some bigger antenna) anyways since I'm moving to a townhome soon. Even though it's in the same area, there will be a row of about 3-4 other townhomes sharing walls between me and the general direction of most of these antennas. Being in a townhome, the HOA will probably not allow me to put an antenna on the roof, either, so it will have to be in my attic (which is still better than what I have right now, with the antenna just sitting on top of my entertainment center).

EDIT: One other question... would I have to worry about any kind of interference from power lines running perpendicular to the towers' signal path, about 500-600 feet behind my antenna?

Channel 8s 1/2 wavelength is around 32 1/4", but with uhf bowtie reflectors used for vhf-hi, you want the length to be a bit longer. 32 inches would be good for channel 12 and 13, 36 to 40 inches would be good for channel 7 and 8.


You (shouldnt), but could have problems, but you really wont know until you try.

This channel is ABC, systems2000, so it's pretty important for me to pick it up. ABC also has a couple other channels on this band that I want (weather channel, traffic channel). Any recommendations on a good VHF antenna? And/or a good VHF-UHF antenna? EDIT: Oh, just saw you were asking about the other UHF frequency. In that case, not very important at all. Basically the only channel I'm really missing out on at this point is channel 8. I get everything else I want, although I will probably need to get either an amp or a bigger antenna to get the signal strength I need for all of them.

I just realized that I might need to upgrade to the DB8 (or at least some bigger antenna) anyways since I'm moving to a townhome soon. Even though it's in the same area, there will be a row of about 3-4 other townhomes sharing walls between me and the general direction of most of the antenna towers. Being in a townhome, the HOA will probably not allow me to put an antenna on the roof, either, so it will have to be in my attic (which is still better than what I have right now, with the antenna just sitting on top of my entertainment center), or maybe outside on the porch.

EDIT: One other question... is it possible for relatively nearby (~100m or so) power lines or transformers, to interfere with reception?

I have been looking for this suggestion. I use a cm 4228 for some of my stations and would like to pick up a pbs low power .15kw on ch 8 that is only 4 miles away. The pbs is about 70 degress off my normal direction, some days I get them some days I don't. Can I insert a rod somewhere on the 4228 that would help. Would it be added to the chicken wire, or touch the bow ties?

RF8 is not the same as Channel 8. Sub-channels are included within RF8. If ABC is all your really after, then my suggestion still holds.


The FCC ruled on this issue years ago and has forbidden HOA's from having such a rule.

Systems 2000 is correct. See post #194 on the AVS OVER-THE-AIR DIGITAL TELEVISION RECEPTION FAQ: New to OTA? Start here! thread.

http://www.avsforum.com/avs-vb/showt...=611957&page=7

Cheers.

I use a CM 4228HD that picks up UHF and VHF channels.

Bah, I was really hoping this would be as simple as

1. Find a good tuner.
2. Find a good antenna.
3. Presto-spagettio, you just saved $60/month in cable bills.

I guess nothing is ever that easy, heh... I'll take a look at that page and see if it answers the rest of my questions. Thanks. I'm thinking I might be better off just getting a VHF/UHF antenna.

EDIT:

Including channels as low as 8? Do you know if you actually get any gain on those channels, or if the signals were just pretty strong to begin with?

Looking for a decent antenna but want to put it in our front bay windo and don"t want something thats too big or obnoxious looking.

Right now for our new Samsung 52 b750 we have an old set of rabbit ears that sometimes the picture gets interrupted when somewhen walks in front of the set.

What are some of the decent antennas that arent too big.


I'm withing 2-3 miles of every television tower in Milwaukee.

If theres an advantage toa powered antenna I could try that but i wouldnt think I need it?

As pointed out many times within this thread, you would do better looking at this thread - EV's Best Top Rated DTV Indoor UHF Antenna Review Test Round-Up Guide.

Hmm. The original CM4228 is already 40 inches wide. By the looks of it here http://www.hdtvprimer.com/ANTENNAS/comparing.html , its not that good for channel 8, but great for channel 9 and 10.

You could try sticking in 44 or 48 inch horizontal rods in the reflector to shift the curve lower.
Edit: Quick modeling shows adding the 44 or 48 inch rods doesnt do much to help channel 8 on the CM4228. They would increase Raw Gain about .6 dbi over what it is now, but the SWR remains unacceptably high at almost 27:1, meaning negative Net Gain. Another option to distort the vhf-hi gain curve would be to increase the reflector to element distance to 14 to 16 inches, but that would reduce your UHF gain. Sorry, it just looks like the CM4228 is stuck with a poor channel 8.

Thanks, 300... I may try the new 4228hd if I can find a decent shipping rate.

OK got my new Winegurd 3000 antenna and gave it a try. First thing i noticed is CBS,FOX single strengths have dropped a lot but the stations are watchable. I have the Wineguard on a table behind a fan right now while the Monoprice was near the top of my wall so I'm not to concerned about that. Got ABC back right away and as i held the antenna higher also got back 11 but lost it again when i put it back down. Figured i would move it around the wall, find the right spot and buy a floating shelf so it can rest on. Sad it can't be hooked to the wall but the shelf will look nice. What is that big plastic thing hooked to the antennas back, clear plastic with tap around it. How does that help, yes i know it's a bow design but don't see how it helped since the single should pass right through the clear plastic part.

dagger,

Here's a spec sheet on the...
Winegard SS-3000 Spec. Sheet

It may help you understand it's capabilities. I generally don't like to even comment on an Indoor Antenna, just TOO many variables in the construction of the building and other factors. It would have been nice at least, to have seen a Chart on your location, the 3000 may not be the right antenna for you anyway.

With Ch8 being at 70-deg, trying to get just ONE antenna to cover both directions
will be very, very difficult, if not impossible, cuz of the NULLS towards the sides.

You should buy or build a second Ch8 antenna and combine it with the CM4228
using a low loss UVSJ VHF/UHF Combiner. A simple Folded Dipole will provide a
Gain of about 2 dBi and the simple Circular Loop about 3-4 dBi....in the right
direction. If you still have problems, you'll need to add a reflector of some sort.

Several Hi-VHF DIY (e.g. Folded Dipole, Circular Loop w & w/o Reflectors) are found here:
www.imageevent.com/holl_ands/loops

Lower TV channels need LESS power (10's vice 100's of kilowatts for UHF)
because the PATH LOSS IS LESS. It's a function of both distance and frequency:
http://en.wikipedia.org/wiki/Free-space_path_loss

Problems with VHF fall into two basic categories:

1) FCC underestimated the man-made noise levels, which affects both outdoor and
especially indoor reception due to the proximity of fluorescent lights, dimmers, motors,
microwave ovens, leaky computers and other A-V Gear. And completely ignore lightning storms....

2) FCC insisted on maintaining the fiction that people are supposed to be using a 6 dBd
(8 dBi) OUTDOOR Hi-VHF antenna at a 30-ft height (with less than 2 dB downlead loss).
Consequently Indoor Antenna users fall 4-6 dB short on Gain and fall much further
behind when VSWR loss (incl. EVM degradation) is calculated:
http://www.tvantenna.tv/papers/PFactorsV.pdf
http://www.tvantenna.tv/papers/dtv%2...prediction.pdf
A UHF Loop is inherently a much better "antenna" than difficult to tune VHF Rabbit Ears.....
As you can see from these papers, there are also OTHER factors that have been underestimated.

I've been collecting Indoor Penetration Loss data for quite some time, but there
is almost NOTHING wrt VHF penetration in modern homes. I have seen one study
cited (unidentified....), claiming that VHF has difficulties penetrating into
modern homes due to the use of chicken wire in stucco and aluminized foil "wraps",
allowing BETTER penetration of UHF freqs via window openings.

HOWEVER, I have also seen specs wherein modern "Low-E" glass attenuates UHF
by about 20 dB (but no data wrt VHF!!!!). So enjoy what's left of the summer.....

So I'm just going to surmise that YMMV......A LOT!!!!!

I'm SW of Warren (Lake Milton) and TVFool shows my kdka reception at -95db compared to the -85db on the scan you show.

From reading other posts, preamp overload would call for pointing the antenna slightly away from direct. Do you think that's still the case given the updated signal strength from TVFool? I wonder especially as my signal strength seems to be stronger at night and in that case the signal is also much more stable. Is that a counter-indication of overload? I tried simply unplugging the power to the pre-amp, but have read elsewhere that that's not the same as taking the pre-amp out of the pathway.

Thanks for the link to the 16 bay. It doesn't seem too complicated. Use the same equipment to ensure that everything is symmetric. Identical cable lengths to the combiner. Match polarities.

Two questions: Can someone provide a good example (model number) of a "low-loss combiner" for this application? I notice in the pictures that the antenna was angled up. Is that because that location was in a valley? My view is essentially flat to the horizon. Do I need to be angled down or is that just knit picking at this point?

Thanks again for your reply

Yeah, and replacing a CM4228 with a new CM4228HD is NOT a good overall trade off.

What do you mean when you say "horizontally"? You mean parallel to the ground plane, right? But perpendicular to the plane of the reflector? Maybe it would be worth it for me to try something like that with my antenna... I'll start experimenting once I move in.

guess I will get a combiner, straighten a coat hanger and go for it... I would think it would not be too difficult to get them, as they are only 4 miles away with a full 15 watts.
I had a pretty good signal on the 4228 until Wed and they completely went away.... I'm thinking they must be having transmitter problems.

My 4228 works very well for vhf 8, but I have it on a rotor and leave it at it's sweet spot.

Yep, but let me double check that with modeling. Is your DB2 the one with 1" X 4" mesh behind it ?
And actually, a 23" - 24" loop with combiner may be a more compact indoor solution for you as well. Especially if the vhf-hi channel is in a different direction from the uhf ones. The DB2 would fit inside the loop.

I would splurge for the 1/4" inch tubing and make a 23" loop as holl_ands suggested. You only need 6 feet of it, and a coat hanger doesnt have enough material, heh.