New QTH/Putting 7-30 G5RV in attic

[KD4LEI]

Based on my fear of heights to go up on the roof of my new 2-story QTH, I have decided to put this antenna in my attic. #I know some of you ask, "why in the world do you have a G5RV?" #It's a decent setup and I haven't had many problems, so it suits what I need at this point and time.

The minimal space I have and the lack of trees doesn't help to strand it outside. #The antenna restrictions aren't as bad, they're more lax than I thought. #So I have some room but my fear of heights prevents me from doing what I would like to do without renting one of those expensive slow crawling 4 wheeled hoists/cranes (boy those would be nice for putting up Christmas lights). #So I am going to settle for the attic and I think this will be okay

I have the materials to suspend the antenna and enough coax to run from the basement up to the attic from outside. #

I am going to keep any exposed part of this thing away from the wooden beams at least two feet.

The insulated ends will be away from anything far enough to prevent arcing and a fire hazard.

Once all is completed, I will check to ensure the SWR's are minimized as best as possible.

Now, I am thinking I have all my bases covered if this all goes correctly. #My gut is telling me otherwise... Maybe I am thinking more into this than I need to.

One being the following...

Seeing that I live in a cold state in the winter with snow and ice a good possibility. #I have a nagging suspicion if I will have trouble getting out with the stuff accumilated on the roof. #SWR's at an unacceptable #.

What do you all think? # http://www.qrz.com/iB_html/non-cgi/emoticons/rock.gif

[N5FOG]

Another senseless G5RV crime about to be committed http://www.qrz.com/iB_html/non-cgi/emoticons/biggrin.gif



FOG

[n0iu]

Yet another reason to join a local club and ask for help in putting up your antenna outside. The only reason to put one in the attic is if you had no other choice because of deed restrictions or something like that.

You might want to consider having an "antenna raising party" with age-appropriate beverages and pizza. That usually helps attract a crowd!

And as far as winter in Omaha, there is an old saying that says, "The worse the weather is when you put up an antenna, the longer it will stay up!"

Scott NØIU

[n4bfd]

No trees outside? Don't own a sling shot?

[N2RJ]

This is one of the rare occasions where I agree with Scott.

If I were in your area, Chad, I'd be out there to help you.

As FOG mentioned it's a crime to put up even a G5RV in the attic, if you have no antenna restrictions.

I consider wire antennas compromise antennas anyway, so why compromise even more?

[WB2WIK]

A few comments from one who has been there and done that lots of times:

-Attics are never as good as "outdoors." Depends on construction materials used. All wood/plywood/asphalt shingles/tar paper type construction, exclusively, isn't too bad. "Other" materials including bricks, cement, stucco, tiles, foil-backed insulation, etc can be absolutely terrible.

-You mentioned, "check to insure SWRs are minimized as best as possible," which for a G5RV doesn't make any sense. The way to "tune" a G5RV is by using an antenna tuner, which is normally down by the transmitter in the "shack." You do not "adjust" a G5RV by changing its wire lengths or anything like that. Just the tuner. The G5RV by design does *not* have a good SWR on most bands -- it's not supposed to.

-You also mentioned, "stuff on the roof" might make an unacceptable SWR. This also shows a misunderstanding of how antennas actually work. The G5RV on its best day should have a lousy SWR on, say, 40 meters. It's designed to be a poor match, made up for by tuning the whole system using a tuner. If it gets a bit better or a bit worse due to snow or ice on the roof, who cares? That doesn't matter at all. What does matter is the impact on antenna performance, which is completely independent of SWR. Unless your home/attic/roof are all built of very good RF-transparent dielectric materials, which is almost never the case, snow or ice on the roof is the least of your problems.

Having said all that, attic-mounted wire antennas for HF *do* work. Of course they work, everything works! I worked South Africa using a 18" Radio Shack clip lead in my garage on 20m, tuning it with only the automatic tuner in my TS-850SAT. Everything works, it's all a matter of how well. With the propagation we have today, right now, and for the next year or so, "everything" works very poorly and only good antenna systems are consistently making contacts at all hours of the day. A G5RV installed outdoors, high and in the clear, will work better than the same one installed in the attic -- that's a reality.

I'd recommend, "get some help" from people who don't mind roofs, ladders, trees, etc. and get that antenna up and out, as far away from the house as possible to minimize RFI both to and from your station.

WB2WIK/6

[W3MIV]

Quote[/b] (WB2WIK @ Dec. 04 2007,13:51)]I'd recommend, "get some help" from people who don't mind roofs, ladders, trees, etc. and get that antenna up and out, as far away from the house as possible to minimize RFI both to and from your station.
I add my two centimes by way of agreement. RFI issues, particularly, can be very irritating (not least to the other denizens of your abode) and with an attic installation you are bound to have imbalances that will exacerbate RFI issues.

Not only would I recommend getting it out and up, but I would also recommend using a full-size G5RV (or just follow Walt Maxwell's advice and put up 100' of wire and feed it with ladder at the center -- 300-ohm is OK, especially the window-type). Cheap. Run coax from your tuner to just outside the shack wall, and feed the transmisson line thorugh a 1:1 current balun or choke.

This is what I use, and I have the wire interlarded through oak and maple braches to hide the install from the neighborhood goon squad, and it is only about twenty-one or two feet above the ground. Works very well for me.

You should be able to get lots of help with a pot of chili and a case of Blatz...

http://www.qrz.com/iB_html/non-cgi/emoticons/wink.gif

[K0RGR]

Like you, I hate sloped roofs, and up here in snow country, they think every house is a Swiss chalet. I literally had to pull myself up to the peak of the garage roof with rope somebody else had conveniently left for me, because I can't stand up on it. I long for the flat-roofed houses of my youth! I had one nearly flat in Iowa, and I miss it, too.

My solution for some time was a long push-up mast bracketed to the house. An even taller mast could be guyed. But even without guys, a mast 10 feet taller than your house should be OK if it's properly bracketed to the house. They sell 50 foot, heavy duty push-up masts, and I believe the house brackets RadioShack sells would work - check to be sure it will fit the diameter of the pipe.

[n0iu]

Quote[/b] (N2RJ @ Dec. 04 2007,02:35)]This is one of the rare occasions where I agree with Scott.
Try not to make a habit of it!

Scott NØIU

[G0GQK]

Sparking off the ends of a G5RV ! How much power you gonna put into that bit of wire ?

You may find that you won't hear much, and you may also find that when your wife is getting a lousy picture on the TV she might get a little teensy weensy upset, so no Brownie points for you !

Then there are also your neighbours who might have problems of RF flying through the power supply.

The only certain way is to have a wire resonant for one band, but who knows, it may be OK, RF is funny stuff.

G0GQK

[VO1GXG]

I have a " G5RV" but it is just tossed up and folded and terrible but i just talked to Morocco http://www.qrz.com/iB_html/non-cgi/emoticons/tounge.gif

[kc4ylv]

How are you going to get a 20-30 foot perpendicular run of ladder line as matching section if the antenna's in the attic?

The entire reason the G5RV works is because the open wire section acts as a transformer - if you have it bent up and not perpendicular from the antenna and going near structures and metal, you're going to have bad issues all around.

If you want a G5RV, put it up outside and let the ladder line hang down freely. If you want an attic antenna, put up a multiband fan dipole and feed it with coax.

[KD4LEI]

Quote[/b] (kc4ylv @ Dec. 04 2007,13:42)]How are you going to get a 20-30 foot perpendicular run of ladder line as matching section if the antenna's in the attic?

The entire reason the G5RV works is because the open wire section acts as a transformer - if you have it bent up and not perpendicular from the antenna and going near structures and metal, you're going to have bad issues all around.

If you want a G5RV, put it up outside and let the ladder line hang down freely. If you want an attic antenna, put up a multiband fan dipole and feed it with coax.
The G5RV I have is the VG Jr with 17ft ladder line.

[KD4LEI]

WIK

What I meant to say is I have an MFJ 941E tuner I use to attenuate the G5RV Jr.

The house I have has aluminum trim on the edges of the house where the roof and siding meet. #I have vinyl siding and the DuPont Tyvek just underneath the vinyl siding. #The only area where there is any concrete or stone is the basement foundation. #Roof is the standard material with tar paper underneath.

GQK asked me how much wattage I was planning to use. #Nothing more than what my 706MkIIG provides and at times I use the full 100w. #I don't have an amp and although I would like to get one, I have no need for one right now. #However, my max average wattage I consistently stick with is about 60 - 70 watts depending on the band conditions. #I back off the power if folks can still hear me well.

BFD... #The closest trees I have are the next street over and behind those folks' homes. #I would have ideally loved to have our home to be built there, but the builder said the particular model we chose was not designed for those lots to support. #So if there are any trees nearby, they are the landscaped ones no more than 10 feet off the ground.

I really need to join a local club as I have failed to get around to doing. #I get so stubborn asking for help because if I feel I can do something, I will go and do it on my own. #However, I am back to square one because of the acrophobia issue and doing it on my own. #I would love to have some fellow hams over just so I can get that antenna up and preferably outside. #The attic was the compromise I was going to have to settle for. I know the less the antenna is being noticed from the outside, that also makes my wife happy too.

Back when I was a senior in high school I borrowed both a tape measure dipole which I placed in the attic and a Ten Tec HF rig from a fellow ham friend. #I was able to get on 10 meters and never really had any problems getting out. #The siding on that home was all aluminum. #I was getting good reports anywhere from 5x7 up to 10 over. #I wasn't running more than say 50 watts at that point and time. I am certain though too that the band conditions then were better than they are at this point and time.

[n4bfd]

Quote[/b] ]BFD... The closest trees I have are the next street over and behind those folks' homes. I would have ideally loved to have our home to be built there, but the builder said the particular model we chose was not designed for those lots to support. So if there are any trees nearby, they are the landscaped ones no more than 10 feet off the ground.

IF that is the case, and you want to chase DX< you really need to consider a vertical. If you are allowed to have one up, go with the Hustler BTV type (http://www.dxengineering.com/Parts.asp?ID=156&PLID=141&SecID=63&DeptID=22&PartNo=HUS%2D6%2DBTV) antenna as it has a slim profile. Staple down some wire in the grass for radials this winter, and by spring you won't see them anymore. Get up a all band dipole as well, at the heights you have to work with it looks like on 40 and 80 it will be NVIS anyway, which would be great for local nets. Join your local club and get some help. One thing hams loving doing is helping put up antennas. EVERYONE loves to talk about antennas, put them up, compare whatever.
We had a local gentleman who recently decided to get back on the air after being away for a few years. He was injured and at home and unable to put up antennas. Once the locals found out, in short order he had equipment and antennas up for everything from 440mhz to 80 meters.

Edit again... if you can't have a vertical up do to restrictions, get patriotic and put up a flag pole/antenna.

[ke4tsp]

FWIW--- rent, rant, borrow, or steal help to get an outdoor antenna (of ANY configuration) first...but

If you are like me (sigh, antenna restricted), then throw away the g5rv, pick up a balanced-wire tuner (preferably one with the balun on the input side, rather than 4:1 on the output), a roll of #12 or larger THHN, and enough ladder line to connect the two. Get as much wire as you can secure under the rafters into a loop configuration (don't cross the wire over itself), then break it and feed it with ladder line- you will be pleasently surprised at how many bands you can load up and operate on.

I live in a three- story townhouse, and operate all bands but 160 from my attic loop.

Oh, yeah... also less interference to contend with when using balanced feed line and balanced antenna system.

I used notched 8" pieces of 3/4" CPVC as standoffs/insulators screwed perpindicular to the rafters and #8 THHN snap-fit into a notch on the other end.


Works great for a compromise antenna. I run legal limit with no issues. I also have 3 other antennas in the attic.