GH with NARODs for VHF-HI & UHF - Page 4 - Canadian TV, Computing and Home Theatre Forums

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post #46 of 580 (permalink) Old 2009-02-01, 12:48 AM
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Simulation results with and without coating are available at AVS (link removed by moderator)

Last edited by d510d180; 2009-02-01 at 09:17 AM.
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post #47 of 580 (permalink) Old 2009-02-01, 03:02 AM
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Here's spec sheet for "THW" building wire showing 45 mil insulation thickness,
bringing the total AWG10 O.D. from 0.105 (bare) to 0.195 inch (coated):
http://www.pittsburghwire.com/pdf/CatalogF4.pdf

Hence "coat radius" is 0.0975 inch = 0.00248 meters (according to WinConvert).

=====================================
AWG10 "THW" is solid copper wire with a single layer of PVC insulation...no extra jacket.
Readily available at my Home Depot....

THW (worse case) has much thicker insulation than what is INSIDE NM-B Romex 10/3 cable:
http://www.pittsburghwire.com/pdf/CatalogF9.pdf
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post #48 of 580 (permalink) Old 2009-02-01, 11:36 AM Thread Starter
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Quote:
(sorry for lack of url, can't post images or link here...somehow).
Yeah, I read the web linking policy of this forum at the top, its considered a competing forum. I think AVSforum does the same thing.

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post #49 of 580 (permalink) Old 2009-02-02, 01:35 PM
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Added a reflector to my GH

From your instructions, I built a Gray-Hoverman about 2 weeks ago and put it in my attic, and with a 24 dB amplifier and with VERY careful aiming (106 degrees) am able to pick up Buffalo's Channel 2 at 76.5 miles. Since it was going in the attic, I mounted the elements on a scrap of plastic sign board material, each secured with shipping tape and plastic wire ties. Didn't find suitable copper wire at Cdn Tire, so used 1/4" icemaker copper tubing. Found it easy to bend precisely using the recommended jig -- got very symmetrical elements. Does hollow tubing change your receive models?

The GH sensitivity was only marginally better than a DB4 coathanger I built in December until in desperation I hung an aluminum foil-covered (24" X 32") reflector about a foot behind the GH, and that made a big difference. Signal strengths ran about 60 to 62 (orange level) and solid for a couple of weeks, but during the Super Bowl WGRZ must have increased the power, for signal strengths during the game ran 70 to 72. Approximately 3+ minutes before the end of the 4th quarter the signal failed completely and I had to switch over to cable. After about 30 to 45 seconds it came back on to about 70 strength and stayed rock solid the rest of the game. Today it is back to around 62. It was a real pleasure to watch the game in "pure" form without the stupid interjections from local greedsters.

Thanks to the Forum for teaching me so much about DTV reception and the construction of an effective antenna. (Can furnish photos if anyone can tell me how.)
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post #50 of 580 (permalink) Old 2009-02-02, 02:09 PM Thread Starter
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Quote:
Does hollow tubing change your receive models?
Nope, the signals are resonating on the outside metal skin for the most part.

Quote:
Approximately 3+ minutes before the end of the 4th quarter the signal failed completely and I had to switch over to cable. After about 30 to 45 seconds it came back on to about 70 strength and stayed rock solid the rest of the game. Today it is back to around 62.
In cases like that typically some large metal object came in between you and the station. It happens to me too because of shipping in Delaware Bay, heh.

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post #51 of 580 (permalink) Old 2009-02-04, 04:41 PM
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Clarification on Dimensions

Hello Everyone, I have started to build the antenna based the the photos here: http://imageevent.com/holl_ands/grayhoverman
Can someone give me a more precise measurements on the element spacing ?(Where the phasing line connects)
It looks like just under 4 inches (based on 1 inch squares) but it's hard to tell.

The phasing lines look like they are 2" apart by 1" height, do they connect on a taper to the elements ?

I did see other diagrams with more label dimensions but wasn't sure if they apply to this design.

Please forgive pickiness but I used to be a machinist (now a hobby) so I'm used to working with tight tolerances.

Any detailed measurements would be greatly appreciated.
Thanks J

P.S. That software you guys use for modeling, can it export 3D CAD data ?
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post #52 of 580 (permalink) Old 2009-02-04, 05:27 PM Thread Starter
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Thats the original GH with my NARODS added in, and I use a 2 inch phasing line gap instead of 25mm. Found here : http://www.digitalhome.ca/ota/superantenna/

What VHF-Hi channels are you after ?

Quote:
P.S. That software you guys use for modeling, can it export 3D CAD data ?
4nec2, and as far as I know cant be exported into CAD programs.

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post #53 of 580 (permalink) Old 2009-02-04, 10:31 PM
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Channels I'm attempting

Thanks for the quick reply! I'm not to concerned about VHF-Hi more for Fringe UHF

I am trying to get the 146 (157) to 149 (160) degrees I posted my TVFool results here http://www.digitalhome.ca/forum/show...542#post873542 (probably the wrong spot) I hope it's possible.

Thanks for clarifying the dimensions. I am working on a slightly different layout for the 1/2 PVC pipe than I've seen so far, I think you will like it!

So far I have to settle for #10 wire for the elements, I have called 6 major electrical suppliers in Toronto Canada and none of them have it. If any Canadians out there have found #6 or #8 solid copper wire please let me know where.

Last edited by JaxxMan; 2009-02-04 at 11:16 PM. Reason: Miss read question asked about VHF-Hi
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post #54 of 580 (permalink) Old 2009-02-04, 11:46 PM Thread Starter
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I'm not to concerned about VHF-Hi more for Fringe UHF
Well then skip the NAROD version and make one of the normal UHF versions. No sense doing more work than you have to, heh.

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post #55 of 580 (permalink) Old 2009-02-05, 12:39 AM
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To better understand what is what, I reorganized 300ohm's NEC file and labeled each
functional sub-section...see 4nec2 file in my imageevent folder.

My 4nec2 file is a simple *.rtf rich-text-file (cuz imageevent doesn't allow *.txt files).
Once downloaded, save as a simple *.txt file and then truncate off "txt", leaving "*.nec".
Each straight wire is defined by a set of (X1, Y1, Z1) to (X2, Y2, Z2) coordinates:
GW No. #segs X1 Y1 Z1 X2 Y2 Z1 radius

where
#segs denotes the number of segments in each straight wire (a NEC thing)
radius denotes the radius of each wire

You might look at editing 4nec2 file so that it can be imported into CAD.

BTW: If you download the (FREE) 4nec2 program, it includes a Geometry Viewer
which can inspect the coordinates and other parameters for each wire:
http://home.ict.nl/~arivoors/
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post #56 of 580 (permalink) Old 2009-02-05, 12:50 AM
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Why not quarter-inch (O.D.) copper tubing normally used with refrigerators???

And NARODs could be 3/8-inch (O.D.) copper tubing.

FYI: Box labels can be misleading...sometimes they indicate INSIDE dimension....
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post #57 of 580 (permalink) Old 2009-02-05, 02:48 AM Thread Starter
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So far I have to settle for #10 wire for the elements, I have called 6 major electrical suppliers in Toronto Canada and none of them have it. If any Canadians out there have found #6 or #8 solid copper wire please let me know where.
Yeah, like holl_ands said, the copper refrigration tubing is fine. Its just a little more expensive and harder to straighten than the #6 copper grounding wire.

That is weird that your major electrical suppliers dont have #6 copper grounding wire. What do you folks in Canada use for home grounding wire ? Is the electrical code that different ?

mlord buys aluminum rod for fair prices in Canada at Metal Supermarket. (a store I dont have down here)

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post #58 of 580 (permalink) Old 2009-02-05, 10:51 AM
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What do you folks in Canada use for home grounding wire ? Is the electrical code that different ?
We use stranded copper wire. Still nice and thick, but bends easier. The individual strands appear to be #10 or #12.

-ml
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post #59 of 580 (permalink) Old 2009-02-05, 11:52 AM
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Like mlord said all the places I called said stranded wire at that size.

I did finally find one place that sells bare #6 Solid J 0.220" dia but I have to buy a 500Ft spool (tvccanada.com) I'll pass on that.

I have been in contact with a few electrician friends and it looks like they might have some old stock and odd peices from comercial renovations.

Quote:
by 300Ohm: mlord buys aluminum rod for fair prices in Canada at Metal Supermarket
I only tried 1 local metal supermarket, perhaps I will call a few others.

Quote:
by holl_ands: Why not quarter-inch (O.D.) copper tubing normally used with refrigerators???
I am using 3/8 copper for the rods and will consider the 1/4" tubing for the elements if I can't find any solid copper, Thanks guys for all the tips!
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post #60 of 580 (permalink) Old 2009-02-07, 07:10 PM
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I've been watching this forum for a couple weeks now and finally made it out to Lowes to buy some parts. I was able to find the elusive #6 bare copper wire for about 68 cents a foot but the 3/8 inch steel rod was over $1.50 a foot. The 1/2 inch conduit steel was much cheaper (like $4 for 10 feet). Would it make a big difference to use 1/2 inch vs 3/8 inch for the reflectors?
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