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Author Topic: Attic antenna advise  (Read 15570 times)
N9MGO
Member

Posts: 24




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« on: September 01, 2017, 08:14:47 PM »

Let me start by saying the question to attic or not, is not really where I'm going with this question.  My concern is about antenna location and routing feed lines.

First some background.  My house is 11 years old, no metallic backed insulation, no hvac in the attic and asphalt shingles and vinyl siding.  We are located in northern Illinois about half way between Chicago and the western border with Iowa.  Our subdivision is small and more or less incomplete after the housing bust.  We are surrounded mostly by farm fields and conservation area.  Not a bad place to live.  Now the down side,  HOA issues, low wife tolerance as well, no real trees to speak of except in the front parkway, the tallest in my back yard is maybe 15', oh and money too.  Also, I live at the end of a court with one street light in the center island, which I think is now some form of LED lighting.  The light itself is a good 50' from my desired shack location.  Since repeater coverage for 2m/440 is pretty good around here, attic antennas should work ok.

Now for the shack info.  Looks like it will be on the second floor in a loft area between the master bedroom and the other bedrooms.  This area will be under the aforementioned attic.  I have 2 older Motorola ex squad car radios, (free), GM300 and Spectra for 2m/440 base units, waiting to have the channels programmed in.  I have an Ed Fong multi band antenna waiting to be put together and installed.  I had thought I might install that one outside at the roof peak, but even thought I figured a single piece of 5' PVC pipe would probably go unnoticed, I don't want to push it.  It should fit in the attic.

Next, I just acquired a Yaesu FT-450D w/ MFJ 929 tuner, (thanks WB0FTY), for HF.  I'm looking at a DX Engineering multi band wire dipole in the attic for it.  All radios would be housed in a  former TV cabinet which has room for them and a laptop for Echolink and digital, should all fit nice and neat and since the doors can be closed when not in use, the wife tolerance factor will improve.  The cabinet would be located near a corner of the loft near the outside wall.

Now for the questions.  First let's assume the HF wire will run under the roof peak which is generally oriented east-west.  It would be feed with ladder line.  So would it be better to have a short run of ladder line, say down to the attic floor and mount the tuner there and run coax  towards the edge of the house and down to the cabinet?  I assume running ladder line down to the cabinet might be a problem if it ran through the same hole as the 2m/440 coax feeder for the Ed Fong antenna.  Don't think multiple holes in the ceiling will improve the wife tolerance.  That brings up the next question.  What sort of separation if any would be prudent between the 2m/440 antenna and the HF wire.  Also, I might throw an old mag mount whip on a cookie sheet up there for a scanner.

It's a bit of an ambitious project for a new guy, but I plan on taking it slow, besides, nothing ventured, nothing gained.  There is a local ham  who I have not met, who lives about 1.5 miles away from me as the crow flies, and he has a fabulous antenna farm at his house, towers, Yagis etc. but it's unicorporated and he can do whatever he wants.  His spouse must be wired different than mine too.

Anyway, any additional thoughts or recommendations would be most welcome.

Thanks in advance,
Mike
N9MGO
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KC3RN
Member

Posts: 200




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« Reply #1 on: September 02, 2017, 03:12:14 AM »

You have two issues that I see initially.  The 929 is not a remote auto tuner, so it needs to be located by the radio.  You'll need to push the tune button on the 929 to get it to tune.  The tune button on the 450 becomes inactive when you use an external tuner.

Second, the 929 is not set up to tune ladder line.  You'll need some type of balun to interface the ladder line to the tuner.  You  can use a 4:1 if your antenna is a doublet, or a 9:1 if it's a single wire.  If you're planning on using this one (https://www.dxengineering.com/parts/dxe-wa-135 I would go with a 4:1, like this http://www.ldgelectronics.com/c/252/products/2/13/1
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AC2RY
Member

Posts: 310




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« Reply #2 on: September 02, 2017, 08:25:42 AM »

Let me start by saying the question to attic or not, is not really where I'm going with this question.  My concern is about antenna location and routing feed lines.

First some background.  My house is 11 years old, no metallic backed insulation, no hvac in the attic and asphalt shingles and vinyl siding.  We are located in northern Illinois about half way between Chicago and the western border with Iowa.  Our subdivision is small and more or less incomplete after the housing bust.  We are surrounded mostly by farm fields and conservation area.  Not a bad place to live.  Now the down side,  HOA issues, low wife tolerance as well, no real trees to speak of except in the front parkway, the tallest in my back yard is maybe 15', oh and money too.  Also, I live at the end of a court with one street light in the center island, which I think is now some form of LED lighting.  The light itself is a good 50' from my desired shack location.  Since repeater coverage for 2m/440 is pretty good around here, attic antennas should work ok.

Now for the shack info.  Looks like it will be on the second floor in a loft area between the master bedroom and the other bedrooms.  This area will be under the aforementioned attic.  I have 2 older Motorola ex squad car radios, (free), GM300 and Spectra for 2m/440 base units, waiting to have the channels programmed in.  I have an Ed Fong multi band antenna waiting to be put together and installed.  I had thought I might install that one outside at the roof peak, but even thought I figured a single piece of 5' PVC pipe would probably go unnoticed, I don't want to push it.  It should fit in the attic.

Next, I just acquired a Yaesu FT-450D w/ MFJ 929 tuner, (thanks WB0FTY), for HF.  I'm looking at a DX Engineering multi band wire dipole in the attic for it.  All radios would be housed in a  former TV cabinet which has room for them and a laptop for Echolink and digital, should all fit nice and neat and since the doors can be closed when not in use, the wife tolerance factor will improve.  The cabinet would be located near a corner of the loft near the outside wall.

Now for the questions.  First let's assume the HF wire will run under the roof peak which is generally oriented east-west.  It would be feed with ladder line.  So would it be better to have a short run of ladder line, say down to the attic floor and mount the tuner there and run coax  towards the edge of the house and down to the cabinet?  I assume running ladder line down to the cabinet might be a problem if it ran through the same hole as the 2m/440 coax feeder for the Ed Fong antenna.  Don't think multiple holes in the ceiling will improve the wife tolerance.  That brings up the next question.  What sort of separation if any would be prudent between the 2m/440 antenna and the HF wire.  Also, I might throw an old mag mount whip on a cookie sheet up there for a scanner.

It's a bit of an ambitious project for a new guy, but I plan on taking it slow, besides, nothing ventured, nothing gained.  There is a local ham  who I have not met, who lives about 1.5 miles away from me as the crow flies, and he has a fabulous antenna farm at his house, towers, Yagis etc. but it's unicorporated and he can do whatever he wants.  His spouse must be wired different than mine too.

Anyway, any additional thoughts or recommendations would be most welcome.

Thanks in advance,
Mike
N9MGO

Regarding 144/440 - you may deal with HOA requesting installation of TV antenna. You do not need to explain them that it will be used for transmission too. HOA should accommodate your request for that.

Now about HF antenna - main problem with attic location is noise level from anything located inside the house. Each small electronic appliance produces broadband noise in HF band. You may find S6-S8 noise level, which practically makes long distance HF communications impossible. You may think about ground mounted vertical. It is possible to make it almost hidden - plant some brush/trees around - this should be allowed. The key here is to have it as far from house as possible. If you add remote antenna tuner, this vertical can be made relatively efficient on most HF bands being only about 30 feet high.
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KM4DYX
Member

Posts: 63




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« Reply #3 on: September 02, 2017, 08:58:46 AM »

A couple of things. If you're running a tuner then a "DX Engineering Multi Band Dipole", (whatever that is) is not required. Just construct the biggest dipole you can in your attic; you can even let the ends hang down or even fold around a bit in the attic, no worry. Feed with window line all the way back to the tuner. Insert a balun to transition from window line to coax. Tune and enjoy.

Even if you end up going with a vertical or something else outside later you will always have an indoor antenna in case of a big weather event or something that knocks down your outside antenna. (Ask me how I know this.)

I would put any other antennas the attic (VHF/Scanner) near the ends of the dipole. Don't obsess on this one.

Let us know what you do and how it works,

73,
Al
« Last Edit: September 02, 2017, 09:02:11 AM by KM4DYX » Logged
N9MGO
Member

Posts: 24




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« Reply #4 on: September 02, 2017, 09:54:58 AM »

Thanks for all the advice, I should have read the manual on the tuner first, yes, it's not a remote tuner, so much for that idea.  I do like the idea of the largest dipole I can fit and let the tuner adjust from there.  As far as feeding that antenna, I'm still wondering if there would be an issue with routing it down to the shack alongside the VHF/UHF coax through the ceiling hole.  I could end it just prior with a balun and coax the rest of the way to the tuner.  Also, I kinda figured locating other antennas near the ends of the dipole would probably be a better solution.  Outside location is not likely to be an option.  I am concerned about RFI, the three bedrooms under this attic all have TV's and my two sons rooms have their computers in the rooms.  Timing might help there, they are up late fiddling with their computers and I am usually at work or sleeping, but it will be a concern.
Mike
N9MGO
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KC1BMD
Member

Posts: 612




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« Reply #5 on: September 02, 2017, 12:48:12 PM »

Rather than drop feed lines through the ceiling from the attic, drill a hole in the plate on top of an internal wall at your radio location (no insulation in internal walls typically making routing cable easier) and drop the feed line down the wall. Install a wall plate at appropriate height to bring the feed line through in the shack. That should improve wife acceptance.

I would be surprised if you have no RFI issues but some people do not, you just have to try. I get noise from my Trane furnace's draft inducer motor in Winter and sometimes the plug-in CO detectors get tripped. I have not solved the furnace issue (even with ferrites on cables and factory RFI kit installed) but I'm enjoying the quiet in the Summer Smiley. The CO detector issue was partly mitigated by going to a different brand (Kidde -> First Alert) but experience is varied on this one among others with similar issues. I get some mild washing machine motor noise but that isn't run all that much with just me and the wife here now. Good luck and share your experience with us!
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N9MGO
Member

Posts: 24




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« Reply #6 on: September 02, 2017, 03:15:55 PM »

Thanks, good to know.  I'll keep my fingers crossed with the RFI issues, but I'll deal with them as best I can if they pop up.

Mike
N9MGO
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KC1BMD
Member

Posts: 612




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« Reply #7 on: September 02, 2017, 05:53:50 PM »

FYI: I have two fan dipoles in my attic (one for 40/20/10m with 40m being physically short with coils, and one for 17m/12m). They are center fed dipoles with current baluns at the feed points. According to my MFJ-854 (of questionable quality and performance), there is still some amount of (what I assume to be common mode) current on the coax outer and also various AC power cords around the shack. I can't determine whether it's common mode as a 3rd current path coming down the coax outer somehow getting past the current balun, or whether the near field is inducing current on any conductor in the vicinity, since my antennas are so close to the operating position. I'm also not sure what level of CM current is normal and acceptable or whether that number needs to be 0 (or at least not measureable to any degree). I might need to start a separate post to get some opinions on that. I guess my point is that for attic antennas, it might be advisable to avoid antennas that are known for CM current, such as OCF and end-fed types and to try to isolate the feed line with a good current balun to at least minimize whatever CM current might be produced.
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N9MGO
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Posts: 24




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« Reply #8 on: September 02, 2017, 06:09:41 PM »

Good point to consider.
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WB6BYU
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Posts: 17195




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« Reply #9 on: September 02, 2017, 08:58:44 PM »

I have only part of my attic accessible (due to blown-in insulation), and managed to install
my VHF/UHF antenna in the part I can't get to.

I used a closet between two bedrooms, as from there I could route the cable through either
wall fairly easily.  (My HF feedline comes into the closet from outside also.)

I started by drilling a hole in the wallboard in the closet, right over the doorway.  You can
only see it if you walk into the closet, turn around, and look up.  The hole is carefully spaced
from the wall to plastic a plastic pipe clamp.  I checked overhead clearance using a mop
handle, then inserted my antenna (vertical dipole in plastic pipe) and secured it to the
pipe clamp.  The combination of the clamp and the snug hole holds it in place, sticking up
into the insulation, and I can route the feedline above the closet door so it isn't noticeable.

Even if you have access to the attic, using a closet makes it easier to bring the cables down
into the house with minimum aesthetic issues, and they can pass out through the walls or
at floor level to other rooms as needed.


With the commercial dipole, the SWR may be low enough that you can feed it with coax to
a tuner beside the radio and have adequate performance.  Otherwise, I've  brought twinlead
down through a hole in the ceiling before, too.
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KC4ZGP
Member

Posts: 1637




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« Reply #10 on: September 03, 2017, 03:02:59 AM »


Herr KM4DYX,

Did your antenna make the infamous coconut sound when it hit your head.

My loop did. The XYL thought it was funny. I didn't. Oh yes I did.

Kraus
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KM4DYX
Member

Posts: 63




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« Reply #11 on: September 03, 2017, 09:29:58 AM »


Herr KM4DYX,

Did your antenna make the infamous coconut sound when it hit your head.

My loop did. The XYL thought it was funny. I didn't. Oh yes I did.

Kraus

Herr KC4ZP,

Nope, I was inside at the time - bad wind storm. My indoor antennas saved the day, though! Well, they saved my playing radio, anyway.

73,
Al
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N9MGO
Member

Posts: 24




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« Reply #12 on: September 04, 2017, 07:20:21 PM »

I did some checking today and found that my attic is nice and tall, at it's peak it's about 10' tall, but at that nice peak, it's only about 30' wide.  The other dimension is about 44' but of course it tapers down significantly.  I still plan on placing the antenna across the peak area at the highest level I can.  I would be interested in hearing thoughts on the best way to fold the ends to fit.  I guess I can pop the 2m/440 antenna pretty much anywhere other than the center of the dipole area.

Mike
N9MGO
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N9MGO
Member

Posts: 24




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« Reply #13 on: September 05, 2017, 10:26:24 AM »

I have also been looking at the TAK-Tenna spiral mounted in the attic. Almost nothing in the way of electrical wiring runs, no HVAC or metallic insulation.  Since it would be about 20' to 25' above the ground, I think it might work well.

Mike
N9MGO
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WB6BYU
Member

Posts: 17195




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« Reply #14 on: September 05, 2017, 11:46:34 AM »

Typically I'd hang the feedpoint of a dipole in the center of the attic and stretch the wires
out towards opposite corners if it will fit.  You can also run the wires along the peak each
direction, then turn them 90 degrees to opposite corners when you hit the wall.

Or at least close to the walls:  I'd use synthetic strings of some sort to suspend the wires
a foot or so away from the woodwork where possible.  The ends have the the highest
voltages, and are also where you will need to tune the antenna, so I'd try to keep them
suspended in the middle of an open space where they are reasonable accessible, rather
than in a far corner you can't reach easily.  But stringing wires in the attic is never ideal,
so you just do the best you can manage.  Just try to keep from folding it back on itself
too much.


The TAK-Tenna requires readjustment whenever you change bands (and possibly within a
band) and will have a very narrow bandwidth that will be affected by the capacitance to
other nearby objects.  You may have trouble tuning it without your body affecting the
resonant frequency.  It won't be particularly efficient, either.  And if you follow the
provided instructions for setting it up, it likely will generate common mode current on
the coax (which may be a more efficient radiator than the "antenna" itself, but you really
don't want that in your house.)
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