Help choosing an antenna

tommymc

DTVUSA Jr. Member
#1
Hi...I just joined the forum and I hope somebody can help me. I'm struggling with a decision about which antenna to purchase before the snow flies. I currently have a 25 yr old chimney mount uhf/vhf combo and amplifier: Here's a picture of my current antenna. It's not pulling in some of the digital uhf channels like 5.1 I don't know the brand, it came with the house. It's about 8 ft long. The amplifier is an Archer 15-1108. Without the amplifier, I get no reception. Here is a TV Fool link for my location:
TV Fool

I'm only 15 miles from the majority of the transmitters, but in the shadow of a mountain so reception is in effect deep fringe. I have been considering several antennas and am open to other suggestions. The folks at SolidSignal suggested a Clearstream C4 but I question the design, windload and vhf capability. I need to pick up high band vhf. I am in a high wind area. The antenna rotor broke last winter, so I have the antenna aimed at 327 deg where all of the nearest transmitters are. Prior to the digital switch, my strongest analog signals were from 60 miles in the opposite direction (ch 31 and 41) It's more distant but I have a clearer shot in that direction. I guess I could replace the rotor, but since all the networks are available in one direction I think it makes more sense to upgrade the antenna and just leave it stationary.

Current reception:
3.1 [CBS] weak but usually watchable 75% of the time
5.1 [NBC] weak signal-breaks up most of the time.
22.1 [ABC] solid
41.1 [PBS] was very strong analog, but rotor is broken so antenna is not aimed that way
31.1 [NBC] see 41.1
33.1 [PBS] usually ok
20.1 [PBS] often better than 33.1
44.1 [FOX] no signal

I'm wondering if my old antenna has degraded over time.....in other words, do I need a significant upgrade, or just a new equivalent?
Antennas I'm considering:
Winegard HD7696P
ChannelmasterCM2020
AntennaCraft HBU44
and of course, the
Clearstream C4
Thanks for any suggestions.
 
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Don_M

DTVUSA Member
#2
:welcome:

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

, Blogger: Orry's Orations
#3
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

DTVUSA Jr. Member
#4
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

DTVUSA Member
#5
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. :embarrassed:

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

Contributor
#6
Hi...I just joined the forum and I hope somebody can help me. I'm struggling with a decision about which antenna to purchase before the snow flies. I currently have a 25 yr old chimney mount uhf/vhf combo and amplifier: Here's a picture of my current antenna. It's not pulling in some of the digital uhf channels like 5.1 I don't know the brand, it came with the house. It's about 8 ft long. The amplifier is an Archer 15-1108. Without the amplifier, I get no reception. Here is a TV Fool link for my location:
TV Fool

I'm only 15 miles from the majority of the transmitters, but in the shadow of a mountain so reception is in effect deep fringe. I have been considering several antennas and am open to other suggestions. The folks at SolidSignal suggested a Clearstream C4 but I question the design, windload and vhf capability. I need to pick up high band vhf. I am in a high wind area. The antenna rotor broke last winter, so I have the antenna aimed at 327 deg where all of the nearest transmitters are. Prior to the digital switch, my strongest analog signals were from 60 miles in the opposite direction (ch 31 and 41) It's more distant but I have a clearer shot in that direction. I guess I could replace the rotor, but since all the networks are available in one direction I think it makes more sense to upgrade the antenna and just leave it stationary.

Current reception:
3.1 [CBS] weak but usually watchable 75% of the time
5.1 [NBC] weak signal-breaks up most of the time.
22.1 [ABC] solid
41.1 [PBS] was very strong analog, but rotor is broken so antenna is not aimed that way
31.1 [NBC] see 41.1
33.1 [PBS] usually ok
20.1 [PBS] often better than 33.1
44.1 [FOX] no signal

I'm wondering if my old antenna has degraded over time.....in other words, do I need a significant upgrade, or just a new equivalent?
Antennas I'm considering:
Winegard HD7696P
ChannelmasterCM2020
AntennaCraft HBU44
and of course, the
Clearstream C4
Thanks for any suggestions.
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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tommymc

DTVUSA Jr. Member
#7
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

DTVUSA Jr. Member
#8
UHF/VHF antenna: another question

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.
 

FOX TV

Contributor
#10
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.

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.
 

JER

DTVUSA Member
#11
I don't see a mast mounted pre-amp in the photo. If its really there, ignore the rest of this.

You probably also want to check to make sure the amplifier is located close to the antenna with only a short coax run from the balun to the amplifier input. This will ensure that you're getting maximum benefit from the amplifier to increase signal to noise level.

I've not tested the Archer amp that you have so I can't speak to its performance first hand. However, I have tested a lot of amps in my lab and I can say that performance varies widely. Given that, you may want to consider swapping to a different model just to see what happens.

If you decide to go this route don't go for the one with the highest gain. You need to look at noise figure, IP3 and P1dB as well. The latter two indicate amplifier linearity and overload resistance. These are really important since there are a lot of strong signals in the air these days that can really wreak havoc in a poorly designed amp, making it impossible to receive weak signals that are present along with them.

If you are in an area that has strong FM stations you may find that an FM trap placed ahead of the amp really helps. Placing the trap behind the amp doesn't help as much since the amp is already saturated and generating garbage. You should probably try the trap first with your existing amp and then try a different amp if that doesn't help.

Good luck!
 

tommymc

DTVUSA Jr. Member
#12
The multi-path issue is an interesting factor. It gets confusing trying to discuss stations performance before and after the digital switch because the frequencies changed but not the numbers.... But I'll try to add some info.

Before the switch, UHF 22 (ABC) was unwatchable because of a strong double image. I assume this was due to multi-path? It is now 22.1 broadcasting on VHF 13 and is our strongest channel.

Before the switch, VHF 3 (CBS) was usually strong with no double images. It is now 3.1 broadcasting on UHF 22. It is usually watchable but with some dropouts.

Before the switch, VHF 5 (NBC) was snowy but watchable with no double image. It is now 5.1 broadcasting on UHF 14 and is only occasionally watchable. It pixelates and drops out.

Before the switch, UHF 44 (FOX) was so snowy as to be not worth watching. It is now 44.1 broadcasting on UHF 43 and is so weak that the converter box shows "No Signal".

Before the switch, UHF 33 (PBS) was watchable, but we watched duplicate programming on UHF 41 which was our strongest signal. It is now 33.1 broadcasting on UHF 32 and is usually watchable.

Before the switch, UHF 41 and UHF 31 were very clear. They are broadcasting from 4x farther away but without as much obstruction. Since our rotator broke last winter, I have had the antenna pointed away from them. During maple sugaring season, I put a homemade DB-4 upstairs in the garage and was able to watch 41.1 while boiling sap out there. So I assume (but haven't tried) that if I rotate my roof antenna in the correct direction, I can pick up 41.1 and 31.1

All of the networks have their towers within a few hundred yards of each other, so if I can just get a little stronger signal, I won't have to mess around with a new rotator.

I thought that my style of antenna was very directional and less prone to multi-path problems. Is that not so? Is there a better choice that will also allow me to recieve VHF? Thanks.
 

Trip

Moderator, , , Webmaster of: Rabbit Ears
Staff member
#13
As notoriously bad a signal as WVNY-DT 13 (22-1) has, whatever you end up with needs to have very good upper-VHF performance.

- Trip
 

tommymc

DTVUSA Jr. Member
#14
I don't see a mast mounted pre-amp in the photo. If its really there, ignore the rest of this.

You probably also want to check to make sure the amplifier is located close to the antenna with only a short coax run from the balun to the amplifier input. This will ensure that you're getting maximum benefit from the amplifier to increase signal to noise level.
The mast mounted part of the unit is actually piggybacked on the bottom of the antenna. Here's a link to the manual. There is a 50ft run of coax to the power unit which also has an FM trap which has been set to "out".


As notoriously bad a signal as WVNY-DT 13 (22-1) has, whatever you end up with needs to have very good upper-VHF performance.

- Trip
With our current antenna, WVNY-DT 13 (22-1) is now our strongest signal. I was looking on Google Earth, and note that the WVNY tower is located about 500ft away and 167ft lower than the other towers.

WCAX-DT22 (3.1) and WPTZ-DT14 (5.1) are the two stations I would like to improve reception on. WFFF-DT43 (44.1) would be an added bonus but I have little hope for that.
 

JER

DTVUSA Member
#15
Sorry, I haven't looked super hard at your particular station config so I can't help there.

If I were you I'd set the FM trap to "IN" unless you absolutely need to get FM from this antenna.

You may also want to look at the gain setting. It depends on how they designed the amp but usually the NF goes up as you decrease gain. On the other hand, if you're getting hammered with some strong signals (even out of band) decreasing it may still help.

The other thing to look at is how well shielded your amp is. If you're in a strong signal environment (FM, etc) the ones that are just a ckt board in a plastic case tend to have pickup direct into the amp. This can cause all kinds of problems. If you decide to get a new one look for one that's sealed up tight in a metal box. Those types have done better in strong signal areas on my test bench.

This is my last post here for a while until the owner and moderators can figure out what kind of forum they want. Some here are worried that I just tried to sell you something. ;)

Good luck in resolving your problem!
 

tommymc

DTVUSA Jr. Member
#16
Here's an update and more questions. I bought a Winegard HD7697P antenna and have installed it on my old (but refurbished) chimney mount. I replaced all the cable with new RG-6, except for a few feet of old RG-59 that runs through the roof and chimney flashing....it was just too hard to try to snake the new cable.
Masts:
I've removed the broken rotator and just aimed the antenna toward the nearest towers. With the rotator gone, I had to connect two mast sections. They have tapered ends which slip inside the next section. How are these supposed to be secured? I put a bolt through, and braced the joint with a piece of steel strapping and U bolts.

Pre-amp:
My old pre-amp was made for a 300 ohm input, and the new antenna has a 75ohm connection. So that isn't going to work. The good news is that the new antenna works better than the old one, even without using the pre-amp. If reception remains steady, I may decide not to replace the pre-amp. There is still one channel that I can't pull in. It is FOX 43uhf. It shares towers with other stations I receive, but apparently is lower power. The meter on my DTV converter shows a very low signal 4-5 out of 100. I need a threshold of 35-40 for steady reception. I know that a pre-amp can't pull in signals that aren't there, but I have to wonder if one would boost the existing signal to the threshold of reception?

Grounding:
This is the only piece left to do. Since the grounding terminal block is supposed to be mounted where the cable enters the house...in this case, the chimney flashing....I mounted it to the bottom of the mast. I intend to run the ground cable along the ridge to the end of the house, then down the side to where the power lines are grounded. What's the best way to secure the cable to the ridge? I have a plastic/asphalt shingle ridge vent and the best I've come up with is to use zip-ties to attach it to the edge of the ridge vent.
Thanks for all your help and great info.
 
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Don_M

DTVUSA Member
#17
Pre-amp: ... There is still one channel that I can't pull in. It is FOX 43uhf. It shares towers with other stations I receive, but apparently is lower power. The meter on my DTV converter shows a very low signal 4-5 out of 100. I need a threshold of 35-40 for steady reception. I know that a pre-amp can't pull in signals that aren't there, but I have to wonder if one would boost the existing signal to the threshold of reception?
You can try a Channel Master Titan 7777 pre-amplifier for its really low noise factor and find out. That would negate signal loss in the cable, particularly if it's more than 50 feet long. Still, I can't offer too much hope. Your suspicion is on target: The Fox station puts out only about 10 percent of the power of the other UHF stations broadcasting from that location. TVFool shows a WFFF signal strength of -105 dBm. That's so weak that under normal circumstances, it's barely detectable above the radio noise floor, which is what the signal-level meter indicates.

Grounding: ... I have a plastic/asphalt shingle ridge vent and the best I've come up with is to use zip-ties to attach it to the edge of the ridge vent.
Can't think of a better plan, myself. Use black zip ties; they'll last longer because they withstand UV degradation better than the white/translucent ones do. Also, be sure to curve the ground line very gently, both below the mount and at the edge of the roof. A "square turn" in the line increases the chance that a discharge might jump to something else on the roof or nearby.
 

tommymc

DTVUSA Jr. Member
#18
The black zip ties did the job. So everything is working pretty well, but the signal on the UHF channels does seem to fluctuate and a few nights ago, 3.1 (CBS) started breaking up. Since my one VHF signal is strong (it measures 60-65 on the converter box meter) I wonder if I should consider a UHF only pre-amp? I'd like to boost the UHF but don't want to over amplify the VHF. Does that make sense?
Is the Winegard 4800 so much noisier that it wouldn't work for half the price of the Channelmaster?

One more question....I have a total of just shy of 50' cable. Eight feet on the mast, 3 ft through the roof and 35ft into the basement and over to the TV. I know the preamp should be placed as close to the balun as possible...mounted on the mast. If I don't get this resolved before the snow flies, how much noise would 11 ft of cable introduce? Until it's safe to get up on the roof, I'd put the preamp in the eaves just below the chimney.
Thanks again for all the good advice.
 
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Don_M

DTVUSA Member
#20
I wonder if I should consider a UHF only pre-amp? I'd like to boost the UHF but don't want to over amplify the VHF. Does that make sense? Is the Winegard 4800 so much noisier that it wouldn't work for half the price of the Channelmaster?
You can use an AP-4800 -- it's not significantly noisier than the 7777 -- but amplifying UHF signals only adds complexity to the coax wiring at/near the antenna/pre-amp. To do this, you'll need two UVSJ band separator/combiners and additional short lengths of coax to separate the VHF signals from the downlead ahead of the amp, and then combine them with the UHF signals again after the amp. Here's how:

• First UVSJ, above the pre-amp: Connect the in/out port to the antenna balun and the UHF port to the pre-amp input.

• Second UVSJ, below the pre-amp: Connect the in/out port to the downlead going to the splitters/TVs, the VHF port to its counterpart on the first UVSJ, and the UHF port to the pre-amp's power-injector output. You read that right: The power injector needs to be installed in the coax wiring before the second UVSJ for the pre-amp to work properly. (Did I mention this was going to be complex?) :becky:

The first UVSJ acts as a separator; the second is used as a combiner.

... how much noise would 11 ft of cable introduce?
None. A longer cable ahead of the pre-amp introduces additional signal loss, though, which means that much less of a margin between the signals and the radio noise floor. Eleven feet isn't significantly longer than three feet on a temporary basis. It'll still be a good idea to move the pre-amp up to the antenna next spring after the snow melts off the roof.
 

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