tommymc

Don_M

The pictured antenna is either a Radio Shack, possibly Archer VU-160, or an equivalent AntennaCraft model. It's built for all channels, from 2 to 69; it was designed for near-fringe reception; and it appears to be in excellent physical condition for its age. When an antenna still looks good, my usual advice is to sand the downlead terminals clean to restore good electrical contact, and then try replacing everything else in the system before replacing the antenna: coax transformer (aka "balun"), the downlead cable located outdoors and the amplifier. All of these components will definitely be in worse condition than the antenna if they're also 25 years old; a new antenna won't do much good if it's connected to worn-out equipment.

Try installing a good balun (by Channel Master or Winegard) and high-quality RG-6 coaxial cable before committing to a new antenna. Connect the new antenna downlead directly to one TV, re-scan for channels, and then check reception. If things improve, there's a good chance the cable and/or balun were worn out. There's also a chance that the Archer amp is too noisy for DTV, or that it was overloading on strong signals now that most network affiliates are at full power.

If things don't improve, that's the time to consider a new antenna. Before making any antenna or amplifier recommendations, though, we need to get an idea of the signal strengths in your area. The tool we use most is at TVFool, which will list available stations at your address. Click on "start here," then fill in the address fields and antenna height on the next page. (Please note: Use GPS position instead, by clicking the "coordinates" radio button, if your house is in a very remote location, or your neighborhood is very hilly. The report will be more accurate that way.) The best way to post the resulting report is to paste the boldface link following "this page can be referenced as" into a follow-up message. Omit the www DOT TVFool, etc., if you like. The report won't disclose the address. We'll also need to know how many TVs and splitters are connected to the antenna, as well as the cable lengths in the system.

FWIW: Of the antennas you mentioned, the Winegard HD-7696P is far and away the best performer. The CM 2020 and HBU 44 might work OK, or might not, depending on signal strengths. Despite maker claims that broadly suggest otherwise, the Clearstream C4 is not designed for VHF reception. It's somewhat useful on channel 13 in fairly level urban/suburban areas, but that's about it. It's a good antenna, but not as good as a 7696, and it's significantly more expensive to boot.

Orrymain

On my list of things to do is figure out similar information about my antenna. It's been on this house for decades, but with DTV, I really only get the channels I'd get if I had an indoor antenna. I'm not reaping any benefit of that big thing on the roof, so either the connects have rusted and corroded, or it just broke somewhere along the line. I can't afford to do anything about it now, but one of these days, I'll have to hire someone to take a closer look at it and give me a recommendation to repair or buy a new one.

tommymc

Don, thanks for the reply. In the interest of full disclosure, my antenna isn't is as great shape as it looks. There has been wind damage which I've repaired with pieces from an old antenna the previous owners left in the garage. If you look closely you might detect that the insulator on the very longest VHF element doesn't match the rest. One of the other insulators has been repaired with Bondo....well, it's been holding for years. Anyway, as I understand it, the elements I've repaired are the the ones for low band VHF which I no longer need. High band VHF works well, it's the UHF that needs a boost.

I did post my TV Fool map in my original post, but here it is again: My TV Fool map If you click on each of the stations you can see a topographic representation of my location with respect to their towers. I'm in a blue/purple area behind a large hill.

I will try cleaning the contacts on the antenna. The balun is part of the amplifier setup, much larger than a standard one...I think the amplifier needs it to work properly(?) I'd be fine getting away with a little cleanup and replacing some cable...although routing the cable down the chimney and into the basement is going to be a job. BTW, there's only one TV, and no splitters.

Thanks again for the info.....I'll check back in when I've worked on the antenna.

Don_M

Apologies for completely missing the TVFool link. I was too busy figuring out that you probably live somewhere near I-89... which the report confirmed, of course.

You have an extremely weak signal environment that calls for the best equipment available: A Winegard HD-7698P antenna, mounted as high as you can raise it; a Channel Master Titan 7777 amplifier; and if you wanted to replace the rotor, a Channel Master 9521a. The 7698 is a high-gain antenna. High gain usually implies "very directional," making the rotor that much more important to good reception.

Good luck, and please let us know how things work out.

FOX TV

Hello, I don't have a lot of detail about the terrain in your area, but it looks like Don M has it right. I have performed this same repair process to several old antennas with good results. I drilled out all of the rivets in the feed points of the driven elements (Which in some cases are steel and rust then becomes a problem).

I use scotch brite to clean off all of the corrosion at all of the connection points, and then coat them with Thomas & Betts brand of conductive anti corrosion protection paste. This product actually has copper ground up in the paste which makes it conductive. I have even used it on automotive batteries with no acid residue showing up after more than 3 years. Be sure to use aluminum or stainless steel rivets or bolts to secure the feed points back to the driven elements.

On another topic in your post regarding the Clear Stream C series of antennas. These antennas work very well for UHF reception. I am a Broadcast Engineer in a very mountainous area of Virginia, and the C series antennas work very well in high multi path areas. We have been out doing field strength tests on our new antennas and transmitters, and have found the C series antennas work in difficult reception areas where other designs come up short in their performance in regards to multi path or weak signal areas.

The tapered design of the driven elements allows for a physical electrical path for every UHF channel in the new DTV band plan. These antennas work very well. I just received a new C5 from Clear stream, but have not had a chance to test it. The C5 is a VHF high band antenna that has good reviews, but I prefer to test them myself with expensive test gear in a real world environment, which would be in the field at viewers actual residences.

I would start by repairing the old antenna, replacing the balun, and running new RG6 Quad shield cable. If I was going to replace the antenna, I would install new cabling anyway, regardless of what I was going to do with the old antenna, so put replacing the cable high on your list, even if you do replace the antenna. You may find that replacing the cabling, the balun, and cleaning up the connections on the old antenna is all that you need to do to restore good reception results.

You may find that the old amplifier is no longer needed, and if it is very old, it can actually have bad or leaking capacitors and other parts that have gone out of spec, thereby adding to your reception problems instead of helping them. Digital tuners do not like a huge amount of signal, and they can actually suffer from signal overload if you are as close to the transmitters like you say.

I also see that your antenna is on the chimney, and furnace exhaust can add to the corrosion factor depending on what type of fuel is used for heat. Oil heat exhaust is very corrosive to aluminum antennas and coaxial cabling.

Good Luck with improving your OTA reception. Free HDTV Rocks !!

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Some people think the Bush administration is responsible for the DTV transition !!

tommymc

Thanks for the great info. I can see I have my work cut out. I'll let you know how things turn out. Regarding the chimney exhaust....that's a triple whammy. I have oil/propane in one flue and wood in the other. The antenna sits closer to the wood smoke. Luckily (in this instance) there are usually good breezes to quickly dissipate the smoke.

tommymc

As mentioned in a previous threat, I have an old chimney mounted UHF/VHF antenna. Since the digital switch, it's not quite doing it's job. Some signals are just at the threshold where they break up. One suggestion was to take the old antenna and clean up the connections, replace the cable, etc. It's been too cold and wet (yes even snowy) to get up on the roof, so I've had some time to think.

I have an old smaller combo antenna. Could I use pieces from it to extend the UHF section of my current antenna? Is there a formula for the length and spacing that this would mess up? Just a thought.

EscapeVelocity

tommypc, lets keep this in the original thread.

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FOX TV

Which channels are you having problems with? Are the VHF or UHF channels giving you the most problems? This information may lead to some more possible solutions regarding your current antenna. Digital signal breakup is in most cases caused by Multi path or ghosting signals and not loss of signal or signal levels. The older log periodic antennas do not address the Multi Path problem very well.

For UHF, the antennas with a backplane reflector perform much better than conventional designs at UHF frequencies in regards to multi path signals. See my avatar for a multi path explanation. You may be able to pic up a little gain from screening in the UHF V shaped reflector on the front of the antenna, but if multi path is the issue, the screen will not address that issue at all.

__________________
Some people think the Bush administration is responsible for the DTV transition !!