Original Gray-Hoverman Generation 2 Thread (Now Closed) - Page 3 - Canadian TV, Computing and Home Theatre Forums

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post #31 of 451 (permalink) Old 2008-08-11, 10:51 PM
 
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Thanks for the help guys. Those numbers you gave are pretty much the same thing I see on geometry edit (.2516).
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9.88558 inches is what I see.
Hey watch it, I've gone metric 300ohm.
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Is your GH10 installed in your attic or outdoors? If it is an outdoor install, do you have a preamp at the GH10 feed-point?
It's not really installed, I just wanted to do a quick test on my deck last night and I did use my channel master spartan3 0068 preamp. The preamp is located at the feed point.
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( Attic locations can have a loss of around -10dB)
I've heard this over and over from people that I know are way smarter than me, but I just think it's a very muddy situation. For instance, I tried and tried to pick up channels 17 & 18 at several outdoor locations (couldn't get more than 10 ft up in the air). One night I put my gen1 sbgh antenna (which I'm VERY pleased with) back in my attic for different reasons. I pointed it right at Roanoke (ch 17, 18, & 30) and lo and behold I found the spot to get signal (except ch 17). Only thing is, reception is only from about 8pm to 10am. The channels drop out during the day. Ch 30 and 18 are pretty much equal regarding reception. I cannot pickup 17, possibly because of interference from another 17 with the same dbm rating (-103).

It's important to note that the attic is the highest place I've tried my sbgh. A steep 2 story house rooftop with no chimney is not my idea of a good safe outdoor installation. But I may get back on the roof again. I was just not that impressed when testing my old cm4221 on the rooftop. Reception seemed just as good in my attic with the 4221. My sbgh is not facing insulation or shingles in the attic, just going through osb board and vinyl siding. So I would think I'm not losing that much signal strength, right? I could go on about how different channels are better in the attic while some are better outside if you care to know.

Like I said, I will give a detailed channel report with tvfool references for my gen1 sbgh and sgbh10 for comparison when I finish the sbgh10 and get a good outdoor place (hopefully) for installation ready.
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post #32 of 451 (permalink) Old 2008-08-11, 11:16 PM
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It's important to note that the attic is the highest place I've tried my sbgh. A steep 2 story house rooftop with no chimney is not my idea of a good safe outdoor installation.
Yep, the SBGH/DBGH needs a good distance off the ground for great performance, more so than bow-tie style antennas, Ive found.

Is it a gable end cape cod style house ? If so, a long pipe extending over the roof top 5-10 feet with one end in cement and a gable end clamp mount lag bolted at the roofs peak would do nicely.

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post #33 of 451 (permalink) Old 2008-08-12, 03:26 AM
 
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got the elements all bent, using 4guage copper

? working with this tough stuff forced me to get aggressive with the vice to keep it all straight. do the teeth marks on the wire surface affect anything as far as reception goes? virtually the whole wire is covered with them as i straighten it out and then did the bends. should i try to sand/polish it flat? maybe it is overkill but i need all the oomph i can get and i'll take the time to do it if it make a difference.

? for the tube reflectors, does anyone know what is the best way to crimp the exposed opening on the far end? i've seen other antenna elements crimp as a way to keep out water and probably improve strength; didn't know if there were any tricks. and i don't mean smashing the whole tip, the front side facing the elements would still maintain its circumferential shape, but the back side would crimp. probably helps a bit on wind loud too.


and as a side note... i went to a respected head local plumber asking him if he would care to try and make the elements for me out of copper tube. he said he would have a hard time getting safe 90degree bends and then straightening out all the soft copper tube and getting the exact measurements. i figured someone who messes with the stuff everyday might be able to whip one out but he didn't seem confident at all and chose not to try. sorta makes sense in that they don't make designs, they just bend to fit and hide it in walls/crawl spaces. i thought he might have suggestions on someone local who works with the stuff - like crafters mentioned in a prior post - but he had no suggestions. he called another plumber he resepected and he turned it down too.

he did suggest hard copper tube and elbows as a solution, although the 135 degree band would take some delicate hand wringing. i'm not sure how the broken contact of elbow to tube joints would affect performance, or how using solder to keep them connected or whatever you used would also affect things...
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post #34 of 451 (permalink) Old 2008-08-12, 08:39 AM
 
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Quote:
Is it a gable end cape cod style house ?
It is a gable end on a "traditional"? 2-story. It's really only a 7-12 pitch (up 7, over 12), which in reality is not that steep, but steep enough for someone not accustomed to getting on high roofs. I'm also not crazy about putting holes in my roof.
Your idea about the long pipe is one idea I had in mind. I noticed one of my neighboring houses had a similar setup, only thing is, there is no antenna attached. Which is great for me because I may ask for it one day since it's not in use! Only problem is, no one lives in the house, but it is owned, and I never know when the owner is going to be there.
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one end in cement and a gable end clamp mount lag bolted at the roofs peak would do nicely.
So it's not necessary to have standoffs attached to the pole and house every 8 feet or so? I'd guess from the ground to the gable peak is around 30 feet, maybe less.
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post #35 of 451 (permalink) Old 2008-08-12, 12:44 PM
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So it's not necessary to have standoffs attached to the pole and house every 8 feet or so?
Not if you use strong pipe, like galvanized water pipe and a strong gable end bracket and the other end is in cement. Its not going anywhere.

Another nice fairly easy setup, if you dont want to attach to a house, is what Ive seen some people do with flag poles. They made a heavy duty pivoting flag pole using two heavy duty pieces of angle iron spaced the distance of the pipe apart stuck in about a cubic yard of cement. Then the pole is made from say 2 inch galvanzied pipe into which another section of say 1 1/2 inch pipe is stuck, into which is say 1 inch pipe is stuck. (Telescoping, with about 6 inches of each section bolted or welded into the other)
There are two holes drilled into the angle iron, one at the top and one at the bottom, which thru a 1/2" bolt is run thru. Then to raise or lower the flag, they just take out the bottom bolt.
Their setup is extremely strong and not floppy at all and would work nicely for antennas too. The key is heavy duty materials. Also by putting a counter balance weight on the end of the pivot, a quite heavy load can be tilted up.

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Last edited by 300ohm; 2008-08-12 at 06:58 PM.
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post #36 of 451 (permalink) Old 2008-08-12, 10:08 PM
 
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300ohm,
The flagpole idea sounds pretty cool. I probably won't go all out like that though, but thanks for the idea. Attaching the pole to the gable peak sounds fine. It's just a matter of me deciding to buy the pipe and borrow a 40' ladder for installation. What I'd like to do is go up on my roof and test before installing an unnecessary pole setup.

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? for the tube reflectors, does anyone know what is the best way to crimp the exposed opening on the far end?
I always thought it was okay to leave the ends open, since surface area is the main concern, but I'm not the most knowledgeable guy around here either. Not sure about the teeth marks on the copper, I only had them on one end and cut that part off after straightening the wire.

ctgottapee,
I'm looking forward to seeing your design. As a matter of fact, I thought I'd go ahead and post a picture of my build (with errors), because it could be longer than I had hoped before I can find time to work out the kinks I spoke of earlier. It will also take more time if I decide to install a 30' pole mount for the antenna.

I'm changing the wood colinear rod support system to a plastic support (to level up the rods a bit better), and downsizing the array.

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post #37 of 451 (permalink) Old 2008-08-12, 11:34 PM
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do the teeth marks on the wire surface affect anything as far as reception goes? virtually the whole wire is covered with them as i straighten it out and then did the bends. should i try to sand/polish it flat? maybe it is overkill but i need all the oomph i can get and i'll take the time to do it if it make a difference.
I would use a file on them. Also have a file brush handy as copper clogs up a file fairly quickly.

Quote:
? for the tube reflectors, does anyone know what is the best way to crimp the exposed opening on the far end?
You dont have to crimp with you dont want to. The main reason for crimping or capping is to stop whistling when the wind blows just right. If the ends are open water will pour out pretty quickly.
Basically you can crimp it slowly and to a certain point in a vice and smooth the ends into a semi-circle with a file like most commercial units do. Of course they have a special cutter to make that crimp.
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he called another plumber he resepected and he turned it down too.
I dont blame em, heh. Did you tell him it didnt have to be water pressure tight ? 1/4 and 3/8 inch copper ells and tees are much more expensive than 1/2 and 3/4 inch copper ells and tees and much harder to find. The easiest and cheapest way to get a ninety degree bend in a piece of 3/8 inch hard copper pipe is to cut 45 degree notches on each side of the center line, but ONLY cut about 80% thru only. Then bend to 90 degrees, and solder the connection. Like Ive said, water tightness is not an issue. With a 135 degree bend the notches would be 22 1/2 degrees on each side of the center.

jdogmoney,

That looks pretty good. Looks like you used the same pex tubing I did to insert the colinear rods.

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It's just a matter of me deciding to buy the pipe and borrow a 40' ladder for installation.
I wouldnt buy new galvanized plumbing pipe, no sense in that. There is a lot of the old stuff available almost for the taking. All you need is decent threads on it. 1 inch galvanized pipe is about 1 1/4 inch outside diameter and 1 1/4 inch galvanized (or black) pipe is about 1 1/2 inch outside diameter. Youll need to know that for your u-clamps.

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post #38 of 451 (permalink) Old 2008-08-13, 07:35 AM
 
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There is a lot of the old stuff available almost for the taking.
Any idea where I could find it for free.
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That looks pretty good. Looks like you used the same pex tubing I did to insert the colinear rods.
It's called 1/2" pvc 1120. The walls are thinner than sch40, but it allows the metal rods to insert perfectly without the need of glue. It's definitely strong enough to hold the rods level. Notice I took your washer idea 300ohm, those small fun-colored triangles are actually Corian countertop samples cut in half.
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post #39 of 451 (permalink) Old 2008-08-13, 12:08 PM
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Scrap metal yards are a good place to get it cheap. They sell iron by the pound. Demolition sites are another. Old plumbing and gas stores that kept old overstock outdoors will let you have it cheap if you haggle.
And look in the newspaper classifieds, under give away free. Over the past few years Ive seen towers given away free for the removal.
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Originally Posted by jdogmoney
It's called 1/2" pvc 1120.
Oh, OK. It looked like the Pex stuff. Yeah, the PVC stuff will work fine. If painted with plastic paint or enamel it will last a good time outdoors. Its tough trying to find the plastic that will fit perfectly, good job.
Corian is good tough stuff. Nice idea about the free samples.

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post #40 of 451 (permalink) Old 2008-08-15, 10:07 AM
 
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Comparing NEC Files

Hi Folks,

I downloaded and installed Arie Voors’ 4NEC2 antenna modeling freeware about three weeks ago. Since then, I have been pretty busy learning how to do some of the most basic functions. This included using the geometric editor to draw simple UHF antennas in three dimensions and specifying proper Theta and Phi angles so the "Pattern" polar coordinate charts for a horizontal frequency sweep of 470 to 700 MHz actually matched up with the direction I thought the antenna was pointing. LOL… It can be very confusing at first.

I began experimenting with modeling the Hoverman design a just a few days ago. Autofils’ and 300ohm’s most recent handy work are just a little too complicated for a newbie. I needed a simpler version the Hoverman antenna and its NEC file. I found a great drawing by Elvis Gump on Generation I Gray-Hoverman Antenna (SBGH & DBGH), page 19, post #284. I found a simpler NEC file on this thread, page 6, post 77 by PappaDigital. I wanted to see if I could build an NEC file from scratch that sort of agreed with somebody else’s NEC file based on what I had learned about the 4NEC2 geometric editor.

Laying out the zig-zag pattern of the active elements and setting up a "voltage source" was pretty easy given that I had been playing with the geometric editor for the last two weeks. I did not include a reflector. The resulting layout even looked like Elvis Gump’s earlier drawing. LOL… then, I used Notepad to open up the resulting NEC file and compare it to PappaDigital’s listing. The GW records in my NEC file looked very different than PappaDigital’s, mostly because I did all my work in inches, not meters. I also used a different gage of wire and I drew the individual wires in a different order than PappaDigital’s listing. Lesson of the day… NEC files are hard to compare.

Have a Great Day,
DTV Student
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post #41 of 451 (permalink) Old 2008-08-15, 01:33 PM
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I also used a different gage of wire and I drew the individual wires in a different order than PappaDigital’s listing. Lesson of the day… NEC files are hard to compare.
When ever comparing anything to anything, its got to be apples to apples and not apples to oranges. Whats nice about 4nec2x is the ability to change from metric to inches anytime you want to. Just click on Settings in the main screen and change Length Unit and/or Radius Unit to what you want. For the wire radius, just click on the wire in Geometry Edit and change it.
What Ive found is that Arie Voors' front end to the Fortran 77 Lawrence Livermore Labs NEC engine behaves with common, similar features like most other Windows programs. For example, Ctrl-A to select all in Geometry Editor. It just takes some time and practice finding out where everything you want to do is. The more you use it, the more youll love it. Experiment, go nuts, heh.

For the simple Hoverman nec files, look at the first few pages in the original Generation 1 thread at Old Sparks models.

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post #42 of 451 (permalink) Old 2008-08-15, 03:15 PM
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300ohm, in post #162 you mentioned that your AGC option vanished. Did you ever figure this out? I can't seem to find it either...

I've been looking at the discussion of adjusting Vsource based on AGC (your post #158 and Autofils' response in #161)... was going to try the suggestions, only to get stuck on the first step

Last edited by rfs613; 2008-08-15 at 04:06 PM. Reason: Correct spelling of Autofils' nick
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post #43 of 451 (permalink) Old 2008-08-15, 07:28 PM
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Did you ever figure this out? I can't seem to find it either...
Nope. I looks like that check box is gone forever, heh. But its not needed. As you notice in that post, there is a way around it so it does exactly the same thing. Hit F7 ( or Calculate - NEC output data F7) from the main screen to calculate, then choose Far Field pattern. In the lower right hand selection boxes, you want options :
1 - ver/hor/tot
1 - minor-axis norm
0 - power gain
1 - average gain.

The last option is the the most important to choose for AGT, the others dont really matter, but I just followed the Help files suggestion. You know you did it right if you get the message "Ground/Loading data will be set for AGT", and at the end of the run you have "AGT results" and the figures showing on the main screen.

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post #44 of 451 (permalink) Old 2008-08-15, 08:23 PM
 
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AGT Check Box - Missing In Action

Hi Folks,

In some of the example NEC files I downloaded, I noticed that the AGT Check Box was missing. This sometimes occurred when I pressed the F7 (Calculate NEC Output Data) and then selected the Generate Far Field Pattern radio button. The Run Average Gain Test check box was frequently covered up by the Expert Setting selection list.

I took a look at the NEC file with Notebook and near the end there was a RP card in most of the examples that had this behavior. After deleting the RP record and reloading the NEC file the Run Average Gain Test check box was often uncovered and back to normal again.

Good Luck,
DTV Student
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post #45 of 451 (permalink) Old 2008-08-15, 09:55 PM
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After deleting the RP record and reloading the NEC file the Run Average Gain Test check box was often uncovered and back to normal again.
Hmm, that RP card is for the Far Field pattern, so that kind of makes sense. But after loading a nec file that doesnt have a RP card, the button is still missing for me. The RP card is necessary for frequency sweeps.

Quote:
I've been looking at the discussion of adjusting Vsource based on AGC (your post #158 and Autofils' response in #161)... was going to try the suggestions, only to get stuck on the first step
Yep, the purpose of that is so you dont have to do a lot of additions or subtractions later on with a long frequency sweep to get the raw gain data accurate. By adjusting to AGT 1 (0 or some teeny tiny number close to zero), raw gain is accurate.

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Last edited by 300ohm; 2008-08-16 at 04:11 AM.
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