GH with NARODs for VHF-HI & UHF

[Grem]

I took 300ohm's info from post #73 and put it into a simple cad file. Most of info near the end .nec file is already basically in ASCI format it just needs a bit of editing to be imported into cad.

Desktop screenshot

If the basic cad info (just lines and points) is needed just tell me the type of file is needed and I will see if I can find a place to put it and put up a link.

[stampeder]

I'm now hosting steinkebunch's DBGH Diagrams & files here:

PDF file: DBGH_VHF_hi_Antenna.pdf

AutoCad DWG file: DBGH_VHF_hi_Antenna_LT.dwg

Text file: NARODmid.txt

Great work, and thanks for everyone's patience.

[Boomer]

steinkebunch, I believe the driven elements should be 10 gauge, same as the NARODS, as per 300ohm's post #1 in this thread...

"Using the basic original SBGH gen1 colinear rod plans (with 10ga elements, 3/8 inch reflectors),..."

The comments under materials in the pdf states #6 wire for the driven elements and 10 gauge for the NARODS which I believe should be corrected.

Nice work. Much appreciated.

Cheers

[red]

Thanks 300 Ohm for modeling the Narods! Though I did a sloppy "add on" of Narods and Narod Reflectors I received outstanding results! I am now able to receive VHF (real) Channel 9, which is the only VHF Digital Channel in my area. This particular station has been nearly impossible to receive in the past, but now it is coming in with some consistency. TV Fool shows this station to have a NM of -11.5, Pwr. -102.3, and is 86.7 miles from my location.

[300ohm]

TV Fool shows this station to have a NM of -11.5, Pwr. -102.3, and is 86.7 miles from my location.

Jeez, thats a weak signal. I would be suspicious of that TVFool figure or maybe your having a Tropo condition right now.

[300ohm]

"Using the basic original SBGH gen1 colinear rod plans (with 10ga elements, 3/8 inch reflectors),..."

The comments under materials in the pdf states #6 wire for the driven elements and 10 gauge for the NARODS which I believe should be corrected.

6 gauge is fine on this design model too, theres only tiny squat in difference in gain.

I do have some comments on the phasing lines (feedlines) that need to be clarified.

The wire in the middle of the phasing lines (feedlines) is not a wire at all, but rather the place where the balun connects to the antenna.

The feedpoint to feedpoint distance of 35 inches that is shown, is for peaking at about channel 46. To peak at other channels and/or to get a little more gain for those surrounding channels, use a feedpoint to feedpoint distance of 2 times the wavelength, minus 2 percent. This of course will make the antenna taller for channels below 46.

The point at which the phasing lines (feedlines) connect to the feedpoints (shown in the pdf as the sketch on the left below) can also be done as on the right with no difference in gain. The important dimensions are the distance between the phasing lines (feed lines) and the distance in front of the driven element. The one on the right is easier to construct.

[red]

Originally Posted by 300ohm

Jeez, thats a weak signal. I would be suspicious of that TVFool figure or maybe your having a Tropo condition right now.

Well, I had waited several days before posting, just to be sure that I wasn't experiencing a tropo condition. Then last night the station faded away. So in this case I would say it probably was tropo reception. But, that brings up another question for me.

I've posted my TV Fool with a red dot beside each station I watch. At the bottom of the list is real channel 14. It comes in day or night, rain or shine, 24/7. I made a point of using lat and longitude rather than zip code, and I climbed up on the roof with a tape measure to get the height of the antenna, at the feed point.

If I subtract from the noise margin figure, 1db for the balun, 2db for preamp noise factor, and then add a conservative 10db gain for the uhf antenna, that should leave me with 2 or 3 stations I can watch. So, I guess the only explanation is TV Fool data is incorrect? I'm confused, but then again, hey, I'm watching TV!

[300ohm]

So in this case I would say it probably was tropo reception.

You wouldnt have to say probably, if you got the tropo weather forecast here, heh : http://www.dxinfocentre.com/tropo.html
From the looks of it, it looks like your tropo moved into the Gulf of Mexico.

I've posted my TV Fool with a red dot beside each station I watch. At the bottom of the list is real channel 14. It comes in day or night, rain or shine, 24/7. I made a point of using lat and longitude rather than zip code, and I climbed up on the roof with a tape measure to get the height of the antenna, at the feed point.

If I subtract from the noise margin figure, 1db for the balun, 2db for preamp noise factor, and then add a conservative 10db gain for the uhf antenna, that should leave me with 2 or 3 stations I can watch. So, I guess the only explanation is TV Fool data is incorrect? I'm confused, but then again, hey, I'm watching TV!

I had a similiar situation (there was no way I should have been getting the station that I did, but I did, and strong) , but then I went to the FCC database for that channel and it turned out that they had many repeater stations. TVFool doesnt really catch that. Repeater digital transmitters are just being experimentally tested on now.

[rogerup]

Apparently it is obvious to everyone but me, even after re-reading this thread and others several times, as to the exact spatial relationship of the NARODs for the SBGH GH6 gen1 design of 300ohm (post #1). I got the length and distance of the NARODs (post #20) for what I want. But are the NARODs, a) in the same vertical plane as the zig zag elements, or are they b) in the same horizontal plane as the stubs, or c) behind AND above?
Also, are the NAROD reflectors (ref C in post #83) in the same horizontal plane as a) the NARODs, or b) the horizontal plane of the reflectors (ref B in post #83)?
I can't seem to find a side view of this relationship as in the superantenna/design thread that would clarify all for me.

Finally, I can get #4 copper wire, #6 copper wire, 1/8 Al rod, 1/4 Al rod, and I have 3/8 Al tubing. I read post #75. But what is the recommended combination?
This should finalize things for me. Thanks ahead of time.

[red]

Originally Posted by rogerup

Apparently it is obvious to everyone but me, even after re-reading this thread and others several times, as to the exact spatial relationship of the NARODs for the SBGH GH6 gen1 design of 300ohm (post #1). I got the length and distance of the NARODs (post #20) for what I want. But are the NARODs, a) in the same vertical plane as the zig zag elements, or are they b) in the same horizontal plane as the stubs, or c) behind AND above?
Also, are the NAROD reflectors (ref C in post #83) in the same horizontal plane as a) the NARODs, or b) the horizontal plane of the reflectors (ref B in post #83)?
I can't seem to find a side view of this relationship as in the superantenna/design thread that would clarify all for me.

Finally, I can get #4 copper wire, #6 copper wire, 1/8 Al rod, 1/4 Al rod, and I have 3/8 Al tubing. I read post #75. But what is the recommended combination?
This should finalize things for me. Thanks ahead of time.

Hey rogerup,

I hope I can help. When I added NARODS to my GEN 1 GH6, I put them 1/2" above the top stub, and 1/2" below the bottom stub, in the same vertical plane. I put the NAROD reflectors in the same horizontal plane as the NARODS. Hopefully this clarifies my photo in post 94.

red



red - horizontal yellow - vertical

[300ohm]

Finally, I can get #4 copper wire, #6 copper wire, 1/8 Al rod, 1/4 Al rod, and I have 3/8 Al tubing. I read post #75. But what is the recommended combination?
This should finalize things for me. Thanks ahead of time.

Well, if you already have 3/8 inch aluminum tubing, thats great for the reflectors.

For the driven elements:
#4 copper is much harder to straighten than #6 coppper. Aluminum rod is already straight, but can you get it in the lengths needed ? 1/4 inch rod will hold up better against birds than 1/8 inch, but is more expensive and harder to bend. I of course would go the cheapest route, within reason, given your local conditions.

[rogerup]

red & 300ohm:
Ahhhhhhhh, yes! Much clearer now. Thanks much to you both!

red - I suppose I could have taken a SWAG but I couldn't make up my mind even though I saw your very helpful photo; with a magnifying glass. One of the support pipes had me faked out. Not your fault, though. I'm hoping to repeat your performance. Although TvFool reports stronggg LOS signal for me on all channels at 60deg, we are notoriously in a black hole here (huge 50' oaks/maples all around for miles). I'm currently using a Radio Shack VU-120XR with CM7777 amp in my attic and having bad digital breakups when the leaves w/rain/wind come out (summer). The antenna is just too bloody big to put elsewhere in the attic and I can't get above the trees, so I counting on the GH.

300ohm - Thanks too. I don't have the knowledge in this frequency range. We have Discount Steel company in the Minneapolis area that I can get Al or steel from, some in 16 foot lengths and some smaller odd lengths by going to the will-call window. They have a very good web site of same name. I have sacrificial antennas for the tubing.

Thanks again!!

[300ohm]

I don't have the knowledge in this frequency range.

In the UHF range, you generally want to stick with driven elements in the 18ga to 7/16 inch range. Ive gone outside of this range, for example on my foldable GH design and build, and still got great results.

[red]

One of the support pipes had me faked out.

Oops! I bet you were looking at the stub where the "bird perch" was initially mounted. I do most of my mods on the roof, and I was in a hurry the day I moved the perch higher up, thinking no one would ever notice if I left the stub intact. Sorry about that!

red

[300ohm]

Red, your bird perch is an excellant innovation. It gives them something to roost on instead of the elements, heh.