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Author Topic: Stealth antenna choice  (Read 972 times)
AF3Y
Member

Posts: 4424




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« on: November 07, 2017, 06:30:03 AM »

Probably getting back on the air after a move, etc.  HOA, etc will frown on a tower, so I am going to give it a try with
less of an antenna than I was used to as well as running barefoot from now on.

My entire backyard/patio is concrete, so no buried radials, for sure. There is a privacy fence around the entire patio!

I am thinking about a Comet CHA-250B (Had one of these
years ago, and it was easy to assemble, erect, and while it was not a pileup buster, it did produce a bunch of QSO's around
the world.) If I dont go with the Comet, I might want to try the MFJ magnetic loop antenna.
Both/either could be mounted out back, and taken down easily at daylight, etc. Height would only be limited as to how high I
want to push it up and then take it down. hi

I Really do NOT want to cause problems for my neighbors,  and as we live quite close and all of us with Directv or Dish antennas, plus
wireless internet antennas, (Third world country, Santee, SC) I am worried that I may become the bad guy,  or at least have to cease and desist.
Which antenna would/should cause less neighbor TV interference problems, perform better (99% CW), and work well around
20 - 25' up?
Thanks for comments.
73, Gene AF3Y
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AF7ON
Member

Posts: 54




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« Reply #1 on: November 07, 2017, 07:13:29 AM »

I've been using the MFJ 1786 loop for a few years now and have found it to work pretty well at a height of around 6' on all bands from 10 m through 30 m.  For a while, I deployed it manually on a speaker tripod and it's now permanently installed on my backyard pool fence out of sight of my neighbors.  One downside is having to tune it when you change frequency, but I use a panadapter which makes it easy to do visually.  One upside is it's a very quiet receiving antenna.

I have also deployed a number of temporary wire antennas using a 40' fiberglass spiderpole, typically so I can work 30m and 40 m at night.

Mike
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AF3Y
Member

Posts: 4424




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« Reply #2 on: November 07, 2017, 07:42:53 AM »

I've been using the MFJ 1786 loop for a few years now and have found it to work pretty well at a height of around 6' on all bands from 10 m through 30 m.  For a while, I deployed it manually on a speaker tripod and it's now permanently installed on my backyard pool fence out of sight of my neighbors.  One downside is having to tune it when you change frequency, but I use a panadapter which makes it easy to do visually.  One upside is it's a very quiet receiving antenna.

I have also deployed a number of temporary wire antennas using a 40' fiberglass spiderpole, typically so I can work 30m and 40 m at night.

Mike

Yep, I have wondered if my lack of patience and the tuning constantly would be acceptable..  I may be better with the ol Comet.
73, Gene
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W1NK
Member

Posts: 606


WWW

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« Reply #3 on: November 07, 2017, 09:27:04 AM »

Glad to see you back here, Gene!

Have you considered a used Force 12 Sigma 5 or the TransWorld TW2010?  Those would at least get you on 20-10, can be mounted in a 5gal bucket, and (speaking from experience with the Sigma5) fairly stealthy.  Back when N6BT was running F12, he suggested small flower pots could be hung from the horizontal arms to make the antenna look like a planter of sorts.

Just a couple of thoughts ...

Frank, W1NK



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K6BRN
Member

Posts: 461




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« Reply #4 on: November 07, 2017, 10:31:37 AM »

Gene:

I have the CHA-250B.  It needs to be up about 25 feet to perform decently.  I'd suggest you consider a MyAntennas EFHW-4010 or EFHW-8010 multi-band wire antenna with built-in matching transformer.  Side by side, they far out perform the CHA-250B and are less expensive.  Also suggest you read the on-line reviews.

http://www.eham.net/reviews/detail/12423

vs.

http://www.eham.net/reviews/detail/5175

When up, the EFHW wire antennas are almost invisible, and you may be able to run it around the perimeter of your privacy fence, either at fence level or up on some unobtrusive poles.  They are ridiculously tolerant of mounting.  I use one of these at a 2nd QTH with an association on the east coast, and nobody has ever noticed it.  Beinbg end fed, it is usually easier to layout and attach coax to than a center fed wire.

To be fair, both the wire antennas and CHA-250B are compromises compared to a nice 3 or 4 element Yagi at 55 feet, but the wire antennas are good enough that even at my main QTH, where I have a TA-33-MWARC Yagi, the EFHW-80102K gets LOTs of use.

If you do go the MyAntennas EFHW route, I suggest you order the higher power versions, especially if you run RTTY, and also order a feedline RF choke.  The EFHW-4010 (~60 feet long) is half the length of the -8010 (~120 feet long), and is easier to put up in limited space, but gives up 80M and the WARC bands.  The wire run can be bent into a V, H or quad shape and still work pretty well, horizontal or vertical.

Suggested components:

http://myantennas.com/wp/product/efhw-8010-2k/

or

http://myantennas.com/wp/product/efhw-4010-hp/

and

http://myantennas.com/wp/product/cmc-330-1k/

or

http://myantennas.com/wp/product/cmc-154-3k/

Have fun!

Brian - K6BRN

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K0UA
Member

Posts: 1380




Ignore
« Reply #5 on: November 07, 2017, 11:00:37 AM »

Gene:

I have the CHA-250B.  It needs to be up about 25 feet to perform decently.  I'd suggest you consider a MyAntennas EFHW-4010 or EFHW-8010 multi-band wire antenna with built-in matching transformer.  Side by side, they far out perform the CHA-250B and are less expensive.  Also suggest you read the on-line reviews.

http://www.eham.net/reviews/detail/12423

vs.

http://www.eham.net/reviews/detail/5175

When up, the EFHW wire antennas are almost invisible, and you may be able to run it around the perimeter of your privacy fence, either at fence level or up on some unobtrusive poles.  They are ridiculously tolerant of mounting.  I use one of these at a 2nd QTH with an association on the east coast, and nobody has ever noticed it.  Beinbg end fed, it is usually easier to layout and attach coax to than a center fed wire.

To be fair, both the wire antennas and CHA-250B are compromises compared to a nice 3 or 4 element Yagi at 55 feet, but the wire antennas are good enough that even at my main QTH, where I have a TA-33-MWARC Yagi, the EFHW-80102K gets LOTs of use.

If you do go the MyAntennas EFHW route, I suggest you order the higher power versions, especially if you run RTTY, and also order a feedline RF choke.  The EFHW-4010 (~60 feet long) is half the length of the -8010 (~120 feet long), and is easier to put up in limited space, but gives up 80M and the WARC bands.  The wire run can be bent into a V, H or quad shape and still work pretty well, horizontal or vertical.

Suggested components:

http://myantennas.com/wp/product/efhw-8010-2k/

or

http://myantennas.com/wp/product/efhw-4010-hp/

and

http://myantennas.com/wp/product/cmc-330-1k/

or

http://myantennas.com/wp/product/cmc-154-3k/

Have fun!

Brian - K6BRN



I agree you will be far better served with the end fed than the cha250b which is a dummy load with a radiating stick and also uses your coax for some additional radiation.  Sure you can make some contacts, but instead of buying an expensive dummy load, buy a cheap MFJ dummy load and put a T coax connector on it.  Then use some wire stuck in the center of the T for a radiator.  You think I am kidding.  I am not.  The end fed is an actual antenna. Yeah it is a compromise but far less of a compromise than a CHA250b.

 You will also see people holding up for the old Maxcomm "antenna tuner"  Which was also a dummy load in the center that they called an instantaneous tuner and you put however much wire on the two wire connectors you wanted.  Or run one to ground and the other to a vertical or whatever.

 It didn't really matter as long as you stayed under the heat dissipation of the dummy load resistor.  yet people will give it a 5 out of 5 rating.  Because it "just works".  They don't want to know how it works.  One reviewer even said, "I am sure it operates on some electrical principal, perhaps long forgotten".  Yeah, right.  There is a sucker born every minute.  Please don't be one of those.

There is always echolink.
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WB6BYU
Member

Posts: 17068




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« Reply #6 on: November 07, 2017, 11:58:02 AM »

The CHA-250B (and similar antennas from other companies) is just an aluminum radiator with a
lossy matching transformer at the base so the SWR doesn't get too high.  You can read
G8JNJ's analysis here.
  A similar length of tubing, or a telescoping fiberglass fishing rod with
a wire inside - and an autotuner at the base and some intentional radials won't be any more visible
and will work better.
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KD6RF
Member

Posts: 573


WWW

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« Reply #7 on: November 07, 2017, 04:21:50 PM »

You may want to think about tuned elevated radials on the privacy fence.  Connected up to a vertical or inverted-L, you end up with nice low angle radiation which is usually what we want for DX. 

Low mounted horizontal antennas generally shoot the energy straight up, which puts one at a disadvantage for longer range CONUS and DX work.....  Although that's exactly what you WOULD want if you are most interests in local-ish NVIS work out to a few hundred miles on the lower bands.

As one most fascinated by DX, my ordering is vertical or inverted-L first, with the CHA type lossy antennas last (for the reasons Dale mentioned above).


If you are interested in the radiation angles and gains of a homebrew non-resonant Inverted-L design (my personal favorite), "End/Base-Fed Inverted-L, 45 ft version, Elevation and Azimuth Radiation Plots" ===> http://vtenn.com/Blog/?p=110



One of my Inverted-L's is partially constructed of #24 black insulated wire for the horizontal run of 22 ft up 23 ft high.  It is quite tough to see if you don;t know where to look.  That may be "stealthy" enough.


Welcome back, and GL on whatever you choose (preferably ALL of the above  Grin )
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VTenn Antennas
Bay Area Technical Equip Rental and Test Range
http://vtenn.com/Blog/
ONAIR
Member

Posts: 3526




Ignore
« Reply #8 on: November 07, 2017, 11:46:33 PM »

Hams at The Villages in Florida have a very restrictive HOA, yet they have found various ways to beat it!  Just check out the "resources" section of their website:  www.K4VRC.com
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AC2RY
Member

Posts: 283




Ignore
« Reply #9 on: November 08, 2017, 05:47:09 AM »

Probably getting back on the air after a move, etc.  HOA, etc will frown on a tower, so I am going to give it a try with
less of an antenna than I was used to as well as running barefoot from now on.

My entire backyard/patio is concrete, so no buried radials, for sure. There is a privacy fence around the entire patio!

I am thinking about a Comet CHA-250B (Had one of these
years ago, and it was easy to assemble, erect, and while it was not a pileup buster, it did produce a bunch of QSO's around
the world.) If I dont go with the Comet, I might want to try the MFJ magnetic loop antenna.
Both/either could be mounted out back, and taken down easily at daylight, etc. Height would only be limited as to how high I
want to push it up and then take it down. hi

I Really do NOT want to cause problems for my neighbors,  and as we live quite close and all of us with Directv or Dish antennas, plus
wireless internet antennas, (Third world country, Santee, SC) I am worried that I may become the bad guy,  or at least have to cease and desist.
Which antenna would/should cause less neighbor TV interference problems, perform better (99% CW), and work well around
20 - 25' up?
Thanks for comments.
73, Gene AF3Y

If you cannot have radials, then you choice is limited to BALANCED antennas. Look at dipole, inverted V and all other similar types to choose what fits your location.
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WY7CHY
Member

Posts: 638




Ignore
« Reply #10 on: November 08, 2017, 06:42:09 AM »

Horizontal Loop antenna

1. Box of eye screws
2. 18-AWG wire (If the trim of your house is white, get white wire. If dark, get black. If sand/brown trim, use speaker wire or similar color.
3. Use the small eye screws and put them in following the trim/eaves of your house. Run the appropriate color wire through it.
4. If you can get more than 120 feet of wire up around the perimeter of your trim/eaves, your loop will work 40m/20m/17m/15m/12m/10m. If you can get 240 feet or more wire, you'll also have a loop that works on 80m also.
5. 4:1 current balun.
6. Put the feed to the balun close to the entrance to your shack. If the distance isn't too far from the balun to the shack, coax is fine. I am using LMR400 (WHITE); but if you're running low power and less than 50 feet, RG-8X is fine. At 50 feet, it's only a 1db loss and can handle 350 watts.
7. Antenna tuner.

I have a single story ranch house with attached 2 car garage. I have almost exactly as I described for you. My only difference is instead of eye screws I have standoffs. I get a lot of snow and didn't want the wire covered by the snow. I run about 250 feet of wire. My house ranges in height from 10 feet high to 16-18 feet high at the peak of the roof. 75% of the wire is at 10-12 feet high. I've had it up for about a year and a half. I've hit ALL of the USA, Hawaii, Canada, Mexico, Belize, Costa Rica, Puerto Rico, Columbia, Virgin Islands, Brazil, Many countries in Europe, Czec republic, russia, lithuania, and a number of other places.

If you get matching colored wire the entire antenna will be almost invisible. I don't live in an HOA, but I don't have any trees to work with, and I can't have a tower because I have "TWF". (The WIFE Factor). So this is about the best I can do. But loops are so forgiving. Unlike other wire antennas, they will work at 10 feet off the ground. Length isn't all that important because loops are multi-band and a tuner will get you on all bands.

CAVEAT: Everyone's house is different. If you live in a metal sided house; or the walls are plastered over chicken wire, then all bets are off. But normally, a loop is a lot more forgiving and easier to do than most other antennas. 120+ feet of wire for 40m and higher; 240+ feet of wire for 80m and higher.
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Born Wild - Raised Proud: 73
Cheyenne, Wyoming
AF3Y
Member

Posts: 4424




Ignore
« Reply #11 on: November 08, 2017, 03:41:35 PM »

Gene:
  I'd suggest you consider a MyAntennas EFHW-4010 or EFHW-8010 multi-band wire antenna with built-in matching transformer.  Side by side, they far out perform the CHA-250B and are less expensive.

When up, the EFHW wire antennas are almost invisible, and you may be able to run it around the perimeter of your privacy fence, either at fence level or up on some unobtrusive poles.  They are ridiculously tolerant of mounting.  I use one of these at a 2nd QTH with an association on the east coast, and nobody has ever noticed it.  Beinbg end fed, it is usually easier to layout and attach coax to than a center fed wire.

Have fun!

Brian - K6BRN


The end fed wires sound interesting and better than the Comet, but as our houses are patio type homes and damned near
on top of each other, I am really concerned about TVI/RFI.  Plus, Directv and Dish network antennas everywhere.  Angry Have you had any problems in that regard?

73, Gene AF3Y
« Last Edit: November 08, 2017, 03:45:32 PM by AF3Y » Logged
KW4GT
Member

Posts: 72




Ignore
« Reply #12 on: November 08, 2017, 04:32:32 PM »

Not sure if it's an option or not, but so far nobody has mentioned stringing antenna(s) in the attic. 
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“Anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that 'my ignorance is just as good as your knowledge.'” ― Isaac Asimov
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