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Author Topic: Attic antenna advise  (Read 15331 times)
KC4ZGP
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Posts: 1637




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« Reply #30 on: October 06, 2017, 12:33:38 PM »


The aforementioned chap is the one I mentioned 70 foot tower 700 watts.
You're having more fun than him.

But when you come through that ceiling, and everyone does eventually,
it won't be just fun or even funny, it'll be hilarious.

Kraus
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K4FMH
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Posts: 431




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« Reply #31 on: October 07, 2017, 08:31:15 AM »

Kraus,

I think the nails are so small relative to HF or even VHF/UHF resonance length and not being bonded that they are relatively inconsequential for reactive or conductive capacitance.

Even the unbounded foil-backed radiator barriers do not seem to affect with bandwidth.

73,

Frank
K4FMH



All those nails holding down the shingles. Hmmm...

Kraus
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LUCYAJONES
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Posts: 16




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« Reply #32 on: October 08, 2017, 10:22:18 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
N9MGOOn account of, know. I'll keep my fingers crossed with the RFI issues, yet I'll manage them as well as can be expected on the off chance that they fly up.
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N9MGO
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Posts: 24




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« Reply #33 on: October 09, 2017, 07:08:48 PM »

Hi all,
Just thought I'd give an update as others have responded to this post.
Unfortunately, not much progress, the weather here in northern Illinois has been unseasonable warm and dry so the XYL has had me on household projects.  No worries though, hope to have my 2M/440 radios programmed soon, just making sure I have all the repeaters I want to use programmed in.  I have checked out my attic and am starting to make plans.  Hope to have the 2M/440 rigs set up soon though.
As far as the HF, my Yaesu FT-450D is still sitting here.  I have decided to upgrade from my General to an Extra ticket before setting the HF rig up.  I have been studying and hope to take my test in November or December at the latest.  Anyway, It's all good and I greatly enjoy everyone's opinions and still want to here about your attic experiences as it appears that this will be my likely avenue to the world of HF.
Thanks,
Mike
N9MGO
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KE0IOU
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Posts: 15




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« Reply #34 on: October 23, 2017, 09:08:36 PM »

Just my 2 cents.  I strung up a 10-15-20-40 center fed dipole in my attic. It does quite well I am working on WAS get a lot of South America some Europe but not great.  My UHF/VHF is attached to PVC pipe which in turn is mounted in a Christmas tree holder.  I had three coax cables run through the wall (a nice guy was running cable at my place of work, he wanted a small side job) so it looks real nice with no unsightly holes. 

I just bought an end fed that I am going to try to run in opposite direction of the other dipole.

This set up while not perfect, gets me on the air, and l have fun.  This is a nice hobby for me but remains that a nice hobby, I do what I can.  I really like the area I live even with restrictions.  I get really annoyed with the anti HOA comments, they are not for everyone and that is fine.

David
KEƘIOU
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N9MGO
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Posts: 24




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« Reply #35 on: October 25, 2017, 06:57:41 PM »

David,
Thanks for the input, I think I'm of the same mindset, I just want to get on the air and make some contacts, aka. have some fun.  Your post brought up a question on my part and maybe you or others might be able to help.  The question is that at some point, I will have my Ed Fong 2M/440 antenna, some kind of HF dipole compromise antenna in the attic.  In addition, I thought I'd like to put a mag mount scanner antenna on a cookie sheet up there as well for my scanner, (mainly aircraft and some public safety bands).  I plan on punching something like a 1" whole in the ceiling of a closet in the loft area where my cabinet will be.  I would route the feed lines down the inside of the closet and out to an unused tv cabinet used to store my radios.  Now, is there likely to be interference or problems by bundling the cables through the ceiling or bundled to the radios?  The scanners cable is RG-8, and the others would likely be some low loss coax.
Mike
N9MGO
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WB6BYU
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Posts: 17192




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« Reply #36 on: October 26, 2017, 08:50:37 AM »

With the antennas that close together, the transmitters likely will overload
the other receivers regardless of how you route the cables.  So, yes, you
might as well bring them all in through the same hole.  Just don't expect
to be able to listen to any receiver (particularly the scanner) while using
one of the transmitters.
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N9MGO
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Posts: 24




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« Reply #37 on: October 26, 2017, 09:29:10 AM »

With the antennas that close together, the transmitters likely will overload
the other receivers regardless of how you route the cables.  So, yes, you
might as well bring them all in through the same hole.  Just don't expect
to be able to listen to any receiver (particularly the scanner) while using
one of the transmitters.

That's kind of what I thought.  Shouldn't be a big deal as I would probably be overwhelmed by too many bands at once.  The scanner is just an afterthought and probably won't be worth the effort, but I was just thinking out loud.
Mike
N9MGO
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W8LV
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Posts: 125


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« Reply #38 on: December 10, 2017, 02:42:54 AM »

I've been thinking about your situation. And tuner situation.

So, it appears (to me) that a tuner is always best as close to the antenna as possible.
So sayeth the literature. And, I observe with Mediumwave (aka "AM") stations,
They always have those little doghouse shed buildings, right outside at the antenna.
Where they have a tuning unit. So, that's the best engineering practice.
At least as far as medium wave goes. I'll assume that it's the same for shortwave.

But most Hams have the tuner inside. Where they can tune it. And it's out of the weather.
Set it outside, and you've of course got to weatherproof it. And maybe hide it.
I'd put it in a grey box and put a Telco symbol on it. And you never know when a dog house, or a bird house, isn't a dog house. Or a bird house. Or a trash can is not a trash can.

But in YOUR case? The glass appears (to me) to be more half full than half empty: You've got the best of both worlds! A place where a remote antenna won't be subjected to weather. So maybe someone out there can tell us if it would be worth your while to get a remote antenna tuner,  and use that as opposed to your "right next to the rig" tuner.

Maybe with your short run to the radio, it's a wash.

Nobody has made it clear, in my mind anyway, on lightning considerations for an attic antenna.

Nor has anyone made it clear, in my mind, how to comply with the National Electrical Code as far as an indoor attic antenna goes.

A lightning spark, or an RF arc, might mean that a Certain Bald Headed Underwriter who "knows a thing or two, because he has seen a thing or two" , could possibly find your claim void. If your house burns down.

So maybe I'm giving you questions and not answers here. But I hope that it's all for the good,  and your Ultimate Attic Antenna Setup!

I'm just throwing it out there, because Thor visited my OUTDOOR low dipole years ago. I was on the air.
I think what saved me is that it hit the neighbors tree first, which it spilt. And then I must have got a side stream and luckily a little less energy. Many years before that, my crystal radio that I had as a kid got hit, and I found it melted to the windowsill next to my bed. I wasn't home at the time when it got hit.

I don't know how much safety you get from an indoor setup as opposed to an outdoor one.
 But not having stuff out in the weather, and instead inside where I should last much longer? A very attractive idea anyway!

When you hit the plate for Radio Clandestine for the first time, it might be wise to use little power, and in CW mode. Having your name and QTH come over the next door neighbors stereo in plain English would be a bit of a giveaway in the early stages. Torroids on your own stuff may be your friend: I could envision a situation where your OWN stuff could pick up the RF, and reradiate it next door. This would be especially true for long lengths, such as telephone wire, catv and long dish network cables. And thermostat cables. Nipping these in the bud might prevent the knock in the door (or more likely, a registered letter) from the Jack Booted HOA Thugs. I'm sure torroids would cost a lot less than litigation, even though it turns th whole "harmful interference" thing on its head, as a matter of practicality. Then, you can gradually turn up the power. If you can see the bones in your hand whenever you hit the key or speak loudly into the Mic? Well then I guess that you don't really need a RF Safety Table at that point to realise that you need to turn the power down a bit... ;-)

We all want to get on the air with the best antenna for our situation,  not hassle others RF wise,
And Safety is of course the Number One Priority.

As far as XYL's go, "out of sight out of mind" aesthetics in general seems to carry the day:
I have yet to see a HAM shack installation on the HGTV Cellophane Light Show: You know, the one where the Twenty-Something Couple explains that their budget to "work with" for the home of dreams is something like 1.1 Million Dollars. Hmmmm. And then some XYL's don't care. And some XYL's are Hams, but they still might prefer the equipment out of site mindset. But I would suppose its pretty rare to find a YL who posts a Collins S-Line on her dating site next to her glamour shot. And even rarer to find a YL with a photo of her WITH her S-Line gear as PART of her glamour shot...

A big easily accessed attic in the house with other attributes that the XYL finds suit her tastes would NO Doubt be the best if you get stuck in a landlocked HOA situation, or you just don't want the hassle of an outside antenna for other reasons. At my age, and health status? I'm not climbing a tower again, ever. I'm not missing my next birthday by trying to do what is no longer practical for me, and I am greatly saddened when I read of a fellow hams demise from climbing a tower. For the last time.


These kind of posts and correspondences are what makes eham.net great.
None of us know when our home situation might change: A job, a retirement,  health status, or the change in status of an XYL to an XXYL could land any of us anywhere... It happens. Nor are any if us getting younger.  It also gives us all an idea of what to look for when house hunting.

Please do us all a favour, and report back here on how it's going:  What works, and what doesn't,  and what works best for you in your situation!

73 and All the Best!
DE W8LV Bill


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K0UA
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Posts: 1464




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« Reply #39 on: December 11, 2017, 11:45:20 AM »

I have an attic fan dipole for 40 thru 6 meters up in the attic.  I assume it is still up there, I haven't used it in well over a decade  There has been an alarm installation crew up there after I abandoned it.. At the time It worked fairly well.  BUT I had a lot less electronics such as an Ethernet network in the house at the time. I suspect it would suck with all the electronics that have been added to the house since I move the ham-shack over to the west end of the house to be near my new tower and beam.  Smiley  The coax from the attic antenna is too short to reach the new shack, and I never bothered to extend it.

So can attic antennas work on HF?  Yes, they can.  You lose a few DB being under the shingle roof, but it still can work.  Modes like CW and digital modes can mitigate the loss somewhat.  You will have to deal with RFI radiated from you devices, and RFI being radiated INTO your devices, as ideally you want your antennas as far from your and every other house as you can get them.  Good luck with your installation.  If I were you, I would get started on a fan dipole, at the very least you can listen and start working on making your house as quiet as possible.
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K7JQ
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« Reply #40 on: December 11, 2017, 02:23:00 PM »

Attic antennas will work, transmit-wise, in a suitable fashion to make QSO's. The problem in today's world is receiving signals. With all the electronic gadgets in a normal household (and your neighbor's)...switching power supplies, wall warts, modems, routers, chargers, cable boxes/DVR's, lighting, computerized appliances, etc...you'll be lucky to hear anything to work. Fifteen years ago, I installed remotely switched mono-band dipoles for 10, 12, 15, 17, 20, and 40 meters in my attic (CC&R antenna restrictions). They worked fine...able to still enjoy the hobby. After all the accumulation of gadgets mentioned above over the years, my dipoles are now virtually worthless...S5-9 noise levels on every band. Trying to find the culprits was fruitless...I'd have to practically shut down every other circuit breaker in the house to operate. And even then, noise from my neighbor's houses was still present. Of course, YMMV.

I've since installed a stealth ground-mounted screwdriver antenna outside, away from the house, and the ham world is good again (well, except for the downturn of the solar cycle Undecided).

73 and Happy Holidays,

Bob K7JQ   
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W1VT
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Posts: 2529




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« Reply #41 on: December 12, 2017, 07:38:20 AM »

A  small external receiving antenna is a good idea--you may also consider an "active antenna."  Rather than tune a short whip to resonance, a high impedance JFET preamp is connected to  effectively "match" the antenna for reception purposes.  R W Burhans is the clever fellow who patented and published this idea in the 1970s.  This idea also works down to VLF if you have interest in the new ham bands.

Zack W1VT
« Last Edit: December 12, 2017, 07:40:35 AM by W1VT » Logged
W8LV
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Posts: 125


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« Reply #42 on: December 12, 2017, 08:02:31 AM »

I wonder about a loop in the attic as opposed to a dipole, as far as noise is concerned.

Also, It seems that people are getting quite clever with small portable loops as yet another alternative.

73 and All the Best!
DE W8LV Bill



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AC2RY
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Posts: 310




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« Reply #43 on: December 12, 2017, 12:32:03 PM »

I wonder about a loop in the attic as opposed to a dipole, as far as noise is concerned.

Also, It seems that people are getting quite clever with small portable loops as yet another alternative.

73 and All the Best!
DE W8LV Bill





If noise is a concern, forget about attic.
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K4FMH
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Posts: 431




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« Reply #44 on: December 13, 2017, 07:14:25 AM »

I currently have both a loop outside (mounted on a 1' pipe) AND 35' up in my two-story house attic. Outside is a Wellbrook ALS-1530+ and the one in the attic is the new MFJ Rx Loop (MFJ-1886). Everyone's mileage will vary on attic Nx and I have security system wires, satellite/OTA antenna coax, ethernet CAT6, on-demand hot water heaters, plus power up there as well as venting pipes.

Now, the attic loop has about a -10dbm higher noise floor (measured on a Perseus SDR with SDR-Console 3) than the outside loop. BUT, the MFJ 1886 delivers a substantial better SNR which yields a clearly superior signal. This is throughout MW through 18 Mhz (only bands I've yet tested in depth). The Wellbrook 1530+ is about a decade old and has been the best Rx antenna I've every used with the Perseus but the MFJ with the highly engineered LNA to handle static and lightning crashes still gets me a better SNR. Plus, it's a lot cheaper (even with shipping) than the UK-based Wellbrook and the DXE Pixel loops.

My two cents: don't let attic Nx keep you from trying a loop up there. Everyone's mileage will vary so direct experimentation---plus perhaps a BHI DSP filter unless you already have an IF DSP---can work wonders even in the face of apparent diversity.

73,

Frank
K4FMH

I wonder about a loop in the attic as opposed to a dipole, as far as noise is concerned.

Also, It seems that people are getting quite clever with small portable loops as yet another alternative.

73 and All the Best!
DE W8LV Bill




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