How to build a UHF antenna... - Page 106 - AVS Forum
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post #3151 of 4798 Old 09-19-2009, 07:20 PM
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Quote:
Originally Posted by 300ohm View Post

Yes, that will work excellent. ( Even a hair dryer will work, given enough time per joint, about 10 - 15 minutes).
I use an old electric heater.
Other methods : Sticking the pipe in a running car tail pipe, heh.

Do I heat all around the pvc pipe at the area to be bent or heat only at the bend point? When making a long curved piece, do you heat the whole pipe and then bend it with your template? I remember you used template to produce equal bends on multiple pieces but don't recall where I saw it... Would this be on the other forum?

Thanks 300 ohm!
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post #3152 of 4798 Old 09-19-2009, 07:28 PM
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I bought some 1 x 1 hardware cloth today for making reflectors. I plan on trying one reflector for UHF only with a 24 inch width. What adjustments should make in plans for an angled and a curved reflector? For the angled reflector, should I shorten the middle section and keep the sides 10 inches long with the same angle? Or keep the middle 16 inches and shorten the sides to 4 inch wings at the same angle as mclapp's plan? Do I keep the curve or reduce it from 3-1/2 inches to say 1-1/2 inches?

thanks!
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post #3153 of 4798 Old 09-19-2009, 07:34 PM
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Originally Posted by akahooper View Post

my site

I like your website. I ought to do something like that.

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post #3154 of 4798 Old 09-19-2009, 10:06 PM
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Do I heat all around the pvc pipe at the area to be bent or heat only at the bend point?

I heated an area of about 6 to 8 inches around the bend point with the electric heater, IIRC. It probably didnt need to be that large of an area, maybe 4 inches would do fine. Only heat it so its soft, but not to the point of burning.
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When making a long curved piece, do you heat the whole pipe and then bend it with your template?

Ive only done one bend at a time. Keep in mind, that plastic gets hot, heh. Gloves are a must.
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I remember you used template to produce equal bends on multiple pieces but don't recall where I saw it... Would this be on the other forum?

Yep, other forum. You need to put it on a template form when hot, and then use a cold wet rag to cool it down quicker. After you make the first couple bends, it gets very easy.
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post #3155 of 4798 Old 09-20-2009, 10:33 AM
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Quote:
Originally Posted by stampeder View Post

Hi akahooper, you can post them on your own site but there are some steps you need to take to adhere to the GPL license... Thanks for asking, and your popularization of the Gray-Hoverman antenna is greatly appreciated!

Thank YOU stampeder! Will do.

And you're quite welcome.

Some details on my DIY antenna builds:
http://mysite.verizon.net/res11d41p/
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post #3156 of 4798 Old 09-20-2009, 10:39 AM
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Originally Posted by jwwm_2 View Post

I like your website. I ought to do something like that.

Thank you Jim!
I just used the free webspace that comes with my internet service.
Problem is you only get 10mb of space and I've got my preliminary business pages up there too. Gotta get my domain & official hosting set up so I can free up some space to finish the antenna pages!

And I was thinking the same about your vid!

Some details on my DIY antenna builds:
http://mysite.verizon.net/res11d41p/
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post #3157 of 4798 Old 09-20-2009, 10:42 AM
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Originally Posted by 300ohm View Post

Yes, it looks correct, given the .5 inch bends.
Use .55 inch, center of wire to center of wire, for the optimum placement if you can measure that close.

Thanks 300!
I'll call for it as 0.55" +/- .05" on the diagram then.

And yes, I think I can measure that close - I own a caliper remember!

Some details on my DIY antenna builds:
http://mysite.verizon.net/res11d41p/
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post #3158 of 4798 Old 09-20-2009, 05:41 PM
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Quote:
Originally Posted by akahooper View Post


And I was thinking the same about your vid!

A Youtube video of the GH would be fantastic. I've thought about doing one, but the problem is time. Never enough. For me, a GH video is 3rd on the list of video ideas, but my family obligations keep me busy. I want to do an outside, reflected version of the McLapp first, but one thing after another eats my time.

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post #3159 of 4798 Old 09-22-2009, 04:40 PM
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Here is a question from a Youtube viewer of my video I can't answer well. If no one can help me I'll tell him to use an antenna preamp, and a distribution amp like the CM3412. Thanks.


"This design looks great and about to build it for attic use. I will use a 2x4 and aluminum foil on paneling reflector. If I want to feed, say, 4 TVs from this single antenna, what sort of splitter would I want, and should it be amplified? Am I better off splitting and amplifying the signal right next to the antenna in the attic, or could that be located 50 or more feet away? My 6 month old coathanger design is picking up corrosion where wire is sanded, even inside, so Ill use AL or CU this time."

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post #3160 of 4798 Old 09-22-2009, 05:31 PM
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jwwm_2,

We need more information, specifically a tvfool report for the poster's location, number of tvs, and total length of cable run in the distribution system. Depending on his situation, one of following should be recommended:

1) no amplification needed,
2) pre-amp recommended
3) distribution amp recommended
4) both pre-amp and distribution amp needed

Response 4 is not a common solution since 2 or 3 will usually do the trick for most OTA set ups.

HTH,

Rick
2)
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post #3161 of 4798 Old 09-22-2009, 05:34 PM
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Quote:


If I want to feed, say, 4 TVs from this single antenna, what sort of splitter would I want, and should it be amplified?

A quality preamp is better than a distribution amp. An output from my CM0264 is split thru two splitters and has no degradation of signal, and Im sure it could be split even more.
Depending on where his TVs are located, he may be better off, like I was, with multiple 2 way splits rather than thru a 4 way splitter. It takes some planning of the coax runs. The main idea is to use the least amount of coax.
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post #3162 of 4798 Old 09-22-2009, 07:24 PM
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To 300ohm and IDRick,

Thanks very much for your first rate answers to my question. This is what I advised, based on your very excellent help.

"Not a simple answer, it depends on your exact situation. Make sure you have decent signal first. Start with 1 TV, and go from´╗┐ there with splitters. If signal degrades, you may need a quality preamp like a CM0264. Planning coax runs is important. Shorter is usually better. In rare cases a distribution amp is also needed, but simpler and less expensive is the way to start."

So, I think I have an acceptable answer, and I thank both of you.

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post #3163 of 4798 Old 09-23-2009, 05:20 AM
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Wow, am I impressed with this thread. I have only read 2/3 of it, but have learned quite a bit. I live about 10 miles SE of Columbus,OH, & was planning to build a 4 bay. I just have a question on whiskers and phase lines size. I have enough #10 aluminum wire for the whiskers only, but have enough #8 aluminum for the phase lines only. Do these 2 have to be the same gauge, or will this combo cause any problems.
This is something for inside, on the first floor, with downtown Columbus inline with most of the towers. In other words, downtown buildings in the way, and other structures.
Thanks for all the great posts in this thread.
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post #3164 of 4798 Old 09-23-2009, 06:10 AM
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#10 will be fine for the whiskers and electrically #8 will work fine for the phase lines but the thick #8 wire may be a but of a pain when attaching the whiskers to the phase lines.
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post #3165 of 4798 Old 09-23-2009, 08:30 AM
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Thanks. What if i used #14 aluminum for the phase lines, with the #12 whiskers? I have some of that,too. I did build one out of an old UHF/VHF antenna,that was given to me on freecycle. I did it wrong, after reading this thread, but it works better then the coat hanger one I built. I am going to do another one, with your specs. I post a pic of the one built from the old antenna later.
Thanks for the info.
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post #3166 of 4798 Old 09-23-2009, 09:03 AM
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Quote:


What if i used #14 aluminum for the phase lines, with the #12 whiskers?

Dont use different types of metals, or youll have galvanic corrosion problems.
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I have enough #10 aluminum wire for the whiskers only

Why dont you just use #10 aluminum wire for the whiskers and #14 aluminum for the phase lines. In that combo, use galvanized steel nuts, bolts, screws and washers. (or aluminum hardware)
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post #3167 of 4798 Old 09-23-2009, 09:54 AM
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Thanks. I wasn't sure if the 14 was heavy enough. Here's a pic of the one I built before I found this site. I scaled it up, from the 7", and it does work much better. I wasn't sure about the phase lines, so i kept them at 2". I'm going to make another one following the specs here.

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post #3168 of 4798 Old 09-23-2009, 10:57 AM
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That looks pretty good. Looks like Antennacraft/Radio Shack standoffs. What are the whisker lengths and the distance between the bowties ? Have you tried a reflector 4 - 5 inches behind it ?

Also what are the bowtie feed point distances ? 2" may be between the wires, but the ends of the bowtie pretrude into the space. Actually, the balun connection point looks to be the narrowest. What is the air distance there ?
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post #3169 of 4798 Old 09-23-2009, 11:57 AM
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The balun connections are 2 1/4" apart. 10" lengths on the whiskers, with a 5 1/2" spacing to center. The whiskers are 9 1/2" apart. if I space the stand-offs away from the mast, I can bring the phase lines into 1 1/4", and move in the whiskers. About 1 3/4" between the whiskers.
I can't do it now, the screws will be up against the mast. I haven't built the reflector yet, but have enough material to do it.
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post #3170 of 4798 Old 09-24-2009, 06:34 AM
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The wider phase line spacing of 2" isn't really a big deal, I found with computer modeling that if you use wider spacings there then you should shorten the whiskers slightly. Also the larger diameter whiskers may need to be shortened as compared to wire whiskers. Usually larger diameter elements resonate at a lower frequency so shortening them will counter act that.
I really don't think you will see a huge improvement by thee tweeks over what you have now.
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post #3171 of 4798 Old 09-24-2009, 09:08 AM
 
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Quote:
Originally Posted by brookwood61 View Post


I wonder if anyone can answer if there is any increase in gain using wiskers that size vs using wiskers the thickness of coathangers.
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post #3172 of 4798 Old 09-24-2009, 11:42 AM
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I wonder if anyone can answer if there is any increase in gain using wiskers that size vs using wiskers the thickness of coathangers.

Probably not an increase in gain, but possibly an increase in bandwidth.
And, it makes good use of materials from an old TV antenna.

If you can not measure it, you can not improve it.
Lord Kelvin, 1883
www.megalithia.com/elect/aerialsite/dttpoorman.html
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post #3173 of 4798 Old 09-24-2009, 11:43 AM
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Thanks for the input 300 & mclapp. Yesterday evening, I put on a Radio Shack little box amp for VHF/UHF(I bought it for a quarter at a garage sale awhile back), so I tried it, to see if any of the lower power UHF stations in Columbus would come in better. They did, and even the digital was stronger. But when I got up this morning, I did another channel scan. At 4AM, I was picking up channel 5.1 & 5.2 in Cincinatti, for about an hour-then it dropped. It was coming it at about 55%-at least 80 miles away. This is temporarily mounted on the back of the TV stand, aimed at the LR window. Roof top mounting is out, no attic, and not sure if I want to put it outside beside or on the porch. The garage is another option. Walls are all brick and insulated, but not insulated in the garage. It does seem to me, that I am catching signal through the window.
What would be the best reflector to build. I have enough of the rod left from the original to use them, but I also have some square grid type of mesh, and a nice piece of decorative aluminum with design and small holes through out.
Thanks
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post #3174 of 4798 Old 09-24-2009, 12:57 PM
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Yesterday evening, I put on a Radio Shack little box amp for VHF/UHF(I bought it for a quarter at a garage sale awhile back), so I tried it, to see if any of the lower power UHF stations in Columbus would come in better. They did, and even the digital was stronger.

You got lucky. Most of the time the noise on those RS units overpowers the gain benefits.

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What would be the best reflector to build. I have enough of the rod left from the original to use them, but I also have some square grid type of mesh, and a nice piece of decorative aluminum with design and small holes through out.

What size mesh and post a picture of the decorative aluminum. Those two choices would be easier than rod reflectors.
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post #3175 of 4798 Old 09-24-2009, 02:24 PM
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The mesh is 1" square, but it need cleaned up some. I was going to use it behind the dec aluminum as a frame. As far as the rods go, I have enough mast, and the original holders that keep the rods straight on the mast, if this type of reflector would be better. I have enough of everything to put 3 rods behind each bay. This antenna I was given was attic mounted since new, and was in excellent shape.

On the decorative aluminum, the squares are about 5/16". It's new, no creases, and has a nice shine to it.

You are right about getting lucky with the RS amp. That's why I didn't get out until last night. It did surprise me tho.
Thanks

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post #3176 of 4798 Old 09-24-2009, 05:33 PM
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For indoor use, the decorative aluminum would be the best. But for outdoor use, it would have high wind load. The mesh would be better for outdoor use.
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post #3177 of 4798 Old 09-24-2009, 07:08 PM
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3 rods behind each bowtie would also be fine for a reflector, not quite as good for rear rejection as the 1" mesh or decorative aluminum but the forward gain would be very close.
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post #3178 of 4798 Old 09-25-2009, 02:41 AM
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Thanks for your replies. I'll read back this weekend about reflectors, and see how big & how to shape & space the reflector. Even with the cost of the aluminum sheet-I bought it at a hardware store sidewalk sale for $6 for another project, & by time I buy a piece of all-thread or bolts to mount the reflector, this revamping is still going to be under $10.
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post #3179 of 4798 Old 09-26-2009, 03:13 PM
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Well, after reading how big the reflector should be on the 4 bay, it would take the 3' x 3' sheet of aluminum I had. No problem using it all, but it would be way to big for inside, other then the garage. So. I built a 2 bay out of more leftover parts. I haven't put the reflector on yet, but it is performing very well, even a little better on channel 6. I did it 10 x 9.5. This is a nice size antenna to mount inside.
Thanks for all the tips I read, through out the thread!!
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post #3180 of 4798 Old 09-27-2009, 03:12 PM
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but it is performing very well, even a little better on channel 6.

Dont confuse everyone, heh. Your channel 6.1 is really RF channel 13 from what I can tell, and should be your strongest station. We look for real channel numbers, not the virtual ones which can be anything.
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