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Author Topic: Got my 570 ft skywire loop up and it turning TV on and off...more  (Read 15334 times)
KC1GCG
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Posts: 186




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« on: December 12, 2017, 04:26:56 PM »

Hi all,
I've been waiting all summer, after deciding to put it up, for the leaves to fall and to "git er dun" before the snow flies and I did it with 2 days to spare.
I have about 570 ft of good ole Lowes 14 gauge stranded wire in about a rectangle around my property varying from 30 ft to 70 ft from tree to tree. Seems to be called a 'Skywire" loop in the ARRL antenna book I have and other articles I researched. It ends about 30 ft above my shack on the first floor and makes it into my shack with 40 ft of ladder line through a home brewed window feed thru connected directly to my  MFJ 989B tuner wire antenna input on the back which has a 4:1 balun built in. The feed-point for the loop would be about in the middle of one end of the rectangle if that means anything.
So far I am beyond thrilled with its performance compared to my various other wire dipoles on 20, 40 and 80M (G5RV, end fed, 1/2 waves) and a 5/8 wire vertical for 20M for xmit and recieve. It seems to beat them all for both local and distance with simple comparisons to stations I hear. It works great on 160 also.
But......I have RF problems that I do not have with the other coax fed antennas. This is my first venture into ladder line also fyi.
I get a hum in my PC speakers that when I run power (say 500W) forces me to shut them off. I can hear myself over my stereo if I leave it on. It also turns on or off my Samsung LED TV as well as the Samsung sound system  for it. If they are on it will shut them off and if they are off it will turn them off. Happens when I run only 100 W also. The TV is fed from a Dish that is only about 15ft from the closest point of the ladder line.
Now I have been reading and have seen some things I could try but my primary concern is if I am blasting my neighbor into insanity turning their TV on and off or with other RFI. I could live with the interference in my own home. I do not think they know about my hobby so its not like they would immediately come a knocking if such was happening. Their living room is about only say 125 ft from my shack and from the antenna at its closest point to them is around 100 ft. My TV to their TV is about say 75ft (houses are close on that side-other neighbors are over 500 ft away on front/back other side.)
I could just ask them but I went through that whole what if series of questions about neighbors when I started in the hobby and have elected to not say anything to them - reading a story here on Eham about one ham that had their neighbor trying to blame him for their clothes washing machine problems helped me make the decision:)  to try to stay below the neighbors radar and simply keep my own operation clean "assuming" that if my TV and stuff are fine their's are too or at least I've done my due diligence. 

I think first easy thing I can do is start trying some different lengths for my ladder line but wanted to post here for ideas before I start hacking ladder line up.
Other option would be to get a 4:1 balun for outdoors and put that around the 30 ft point for the ladder line and run about 10 ft of coax into the shack if that would help.
For some variables in that, if you think its a good idea and will not degrade performance much. (I heard an Aussie at s7 last night before he started a long rag chew with someone and that's a first so I'm really reluctant to do anything to 'weaken' this antennas performance) my other wire antennas come to an Ameritron remote coax switch outside my shack that comes into my shack down thru the basement with a run of about 20 ft or so of coax.
So If the outside balun to coax is a potential fix to the RFI I have two options, run the coax straight thru a window feed through set up to my tuner for about 10 ft of coax total or connect it to my remote coax switch which would then be about 10 ft of coax to the switch from the ladder line/balun and then the 20ft thru the basement for a 30 ft total. Either is an ok option for me with the remote coax switch being the cleanest.
Or any other ideas welcome to help me slap this RFI down.
Thanks for reading and your ideas.
K1JRF John


 
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G4LNA
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« Reply #1 on: December 13, 2017, 06:00:00 AM »

Just because you are using open wire line, don't assume it's balanced, it probably isn't and the silly little voltage balun they use in the MFJ matching units don't do anything to balance the lines.

You need a decent 1:1 or 4:1 current balun on the end of the lines before it goes into the matching unit.

Just as an example, I use about 60 feet of 300 Ohm ladder line on my doublet that runs inside conduit along the wall outside to the shack and get no radiation off the feeders at all, I'm using a home brew double L match unit with the 1:1 balun on the input to the matching unit. If I try and unbalance the feeders not only does the local noise rocket up but the feeders radiate like crazy.

So it's worth trying to get those feeders as balanced as possible.
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WB4SPT
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« Reply #2 on: December 13, 2017, 07:13:57 AM »

Good advice to tame down the feeder.   Look at the balun designs that does not use coax.  Its a great unit for use with tuners.  Of course, this will not solve issues from direct antenna radiation.
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K0UA
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« Reply #3 on: December 13, 2017, 07:40:55 AM »

I would start working on the TV and Stereo.  They are not supposed to respond to HF RF.
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73  James K0UA
ARRL Missouri Technical Specialist
G4LNA
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« Reply #4 on: December 13, 2017, 11:09:51 AM »

Good advice to tame down the feeder.   Look at the balun designs that does not use coax.  Its a great unit for use with tuners.  Of course, this will not solve issues from direct antenna radiation.

Indeed, thanks for that, yes don't use the coaxial type balun which is really a choke. This is the type I use wound on an FT240-43 core using PTFE or Teflon sleeved wire. Of course, you can do much about direct radiation, your antenna might just be that much more efficient.

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K6DDJ
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« Reply #5 on: December 13, 2017, 12:28:09 PM »

Hi,
Hope you end up fixing this problem.  Just a little info on my experiences.  I believe you are simply overloading the items or appliances that you are getting into.  I had the same issue here.  What I found out was absolutely amazing................the items that were picking up my signals, turning on or off, etc. were ones that have a touch switch or switches to operate them.  My computer monitor had a touch switch to power it on.  The washing machine had one to power it on and off plus other functions.  The kitchen stove overhead lamp and fans have touch switches.  Finally, the room air filtering machine had all touch switches.  Every time I transmitted over about 200 watts, the stove light or fan came on, or the air filter would change fan speed, or the computer monitor would turn off and on......you get the idea.  The switches are the problem.  You see, on those items, the switch is capacitive.  When you touch the switch you change it's capacitance thereby changing the steady state of the oscillator frequency and then the item executes the command, either turning on or off, or performing some other function.  Unfortunately, that same capacitance of the switch acts like an antenna so when you transmit with power, the item does not know whether you touched the switch or if it is RF overload, and therefore operates the items function.  If you look at all the items in your home that are having problems, you might just find several that are touch switch related.  Not much you can do with this other than replace or unplug the angry item while you are on the air or somehow increase the physical distance between the antenna and the item experiencing the trouble.  If it is just simply a matter of rf overload, you can verify this by starting out with QRP power and then slowly increasing your power.  If all is well at QRP but at say many tens or hundreds of watts you start having the problems, then it is not your rig, your antenna or coax.  It is just that your antenna is too close to the appliances.

Just something to ponder...............good luck!
Dean K6DDJ
« Last Edit: December 13, 2017, 12:47:39 PM by K6DDJ » Logged
WB6BYU
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Posts: 18385




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« Reply #6 on: December 13, 2017, 02:24:27 PM »

I'd suggest two possibilities:

1) direct pickup of RF from the antenna.  Not much you can do to prevent that, other
than applying ferrites to any wires connected to the device (power cords, speaker
cables, etc.) that may be acting as an antenna.  The speaker wires on your stereo are
a prime candidate for this:  seems to me that a lot of speaker wires are resonant around
40m.

2) common mode current getting into the AC power wiring and propagating to the
devices.  I haven't had a lot of problems with common mode currents with loops, but it
can happen (especially if the wire breaks somewhere) and the 4 : 1 voltage balun
provided in many tuners doesn't help much in that situation.  The first step is to measure
the resistance between the two ends of the feedline in the shack:  if it shows an open circuit
then you have a broken wire somewhere in the loop.  Then try using a 1 : 1 current balun rather
than a voltage balun and see if that makes a difference.  (You might be able to reconnect
your existing balun as current balun rather than a voltage balun depending on how it is wound.)


Any common mode current on your power wiring shouldn't propagate to your neighbors
at enough strength to cause a problem.  And the radiation from your antenna obeys the inverse
square law, so twice as far away receives 1/4 of the power.  So chances are that it isn't bothering
them.  However, if you happen to be chatting with them, you could  mention  you were having
problems with your appliances turning on and off, or otherwise doing funny things, and see if they
take the bait and mention any problems that they are having.
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K8BYP
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« Reply #7 on: December 15, 2017, 11:08:36 AM »

"570 ft of good ole Lowes 14 gauge stranded wire

Thats is not an antenna, its an open circuit. That long a length of #14 is approximately 400 uH (Grovers formula) which is an open circuit (31Kohm @ 14.2 Mc)  at HF compared to a 50 ohm feedpoint.

The skin losses are out of sight.

What youve got there is (crudely put) a Beveridge antenna, with a total loss on the end. Its more or less a bent dipole..

The open wire is the main problem, it radiates badly (see theories on parallel inductors and mutual inductance) and its inside the house to radiate away. There must be a current node somewhere near the TV.
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K6DDJ
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« Reply #8 on: December 15, 2017, 03:58:29 PM »

"570 ft of good ole Lowes 14 gauge stranded wire

Thats is not an antenna, its an open circuit. That long a length of #14 is approximately 400 uH (Grovers formula) which is an open circuit (31Kohm @ 14.2 Mc)  at HF compared to a 50 ohm feedpoint.

The skin losses are out of sight.

What youve got there is (crudely put) a Beveridge antenna, with a total loss on the end. Its more or less a bent dipole..

The open wire is the main problem, it radiates badly (see theories on parallel inductors and mutual inductance) and its inside the house to radiate away. There must be a current node somewhere near the TV.



Hi K8BYP.  He is not using a long wire or beverage antenna in which case you would be correct.  If you read closer, he says the 570 feet is in the shape of a rough rectangle which implies that he is building a loop antenna.  Easy to skip over.

Dean K6DDJ
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KC1GCG
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Posts: 186




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« Reply #9 on: December 17, 2017, 04:08:51 PM »

Thanks all for the great replies and ideas. Lots to learn and research which is another reason why I love this hobby and the folks in it!
For clarification, the interference on MY tv's etc is of no concern really unless it is an indication a problem.  I like the adage of keeping your own house clean with regards to any concern about this causing a problem for my neighbors.
It is a 570 ft loop - about a rectangle and connected to 40 ft of ladder line to my tuner in the shack.
Someone on the air mentioned that the usual balun in an old MFJ tuner is a voltage balun and I have read that can be a nice radiator of harmonics so as some of you suggested that will be the first thing to go.
Now I see prices ranging from $30 for a 4:1 Undilla balun to over a $100 in the DX eng catalog. Is it a you "get what you pay for type thing"? I am also going to order some stuff from Amidon so that I can start making my own but I'd rather "solve" this with a known entity, not my first try at winding a balun myself.
Also someone mentioned I could possibly rewind the balun in the tuner to make it a current balun but is there anyway to know if the core is inferior or not? Its about 2.5" outside diameter so it would be a shame to chuck it ...unless its junk.
I don't think I have any breaks in the wire as it works really sweet on the receive and Xmit side beating my dipoles and wire vertical so far. I do have an antenna analyzer but have not yet figured out how to hook it up to ladder line. Something to search for tonight I think.
Thanks again folks and I will update when I find a solution or something else pertinent.
Merry Xmas and Happy New Year and/or the holidays you enjoy this time of year...
Best regards John K1JRF
 
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N3HEE
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« Reply #10 on: December 18, 2017, 08:11:02 AM »

I have a 300 foot loop fed with 100 feet of "carefully" run 300 ohm window line.  Make sure your feed line is not too close to metallic objects.  I use a DXE 1:1 current balun in the shack with a 3 foot coax jumper to my tuner.  No problems with RFI running legal limit.  Feed line runs very close to satellite dish, TV and stereo. 

https://www.dxengineering.com/parts/dxe-bal050h10at
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Joe
N3HEE
CW Academy Advisor (Level II)
N4KC
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« Reply #11 on: December 24, 2017, 09:38:32 AM »

 
John,

I've been "loopy" for a long time now, and an article I wrote for eHam...available in printable form at www.n4kc.com under the "Articles" tab...has gotten tons of response.  I am hardly an expert but I love the antenna and just spent two days getting mine back up after having to take down some beetle-infested pines that served as supports.  Two days in a cold rain! But I also got it a bit higher and added 100 feet of that good old Lowe's THHN wire to make it now about 570 feet long.

At any rate, sounds as if you are doing most of it right, but I concur on adding a good current balun to assure this perfectly balanced antenna is just that, as much as you can. I do use one of the DX Engineering 1:1 current baluns rated at 5 KW.  That is overkill, I know, for my 1 KW station, but you can build up some really high current in the balun when the antenna is being used across the spectrum into a wide range of impedances.  (I also use a 4:1 version on my 80-meter dipole with good results.)

Note that I use 450-ohm window line (likely closer to 390 ohms, but who's counting?) to a 20-foot run of parallel coax cables...using the center conductors on each as extensions of the two conductors of the window line...to the 1:1 balun mounted on the wall beneath the operating desk, and then a 3-foot coax jumper to the MFJ-998 auto-tuner.  It works well, tunes everywhere in the spectrum where I've tried it, is remarkably quiet, and even, on rare occasions, outdoes my hexbeam.  Oh, and it doesn't turn my TV on or off! 

(I did have that issue with the window-line fed dipole and even the hexbeam until DirecTV replaced the dish and LNA with an updated version. On some bands, I not only turned the sat receiver on and off, but I started it recording, changed stations, and even scrambled my program guide options.  Now, no problems.)

73,

Don N4KC
www.n4kc.com
www.donkeith.com
   
   
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WB6BYU
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« Reply #12 on: December 24, 2017, 11:02:49 AM »

Quote from: KC1GCG

...Someone on the air mentioned that the usual balun in an old MFJ tuner is a voltage balun and I have read that can be a nice radiator of harmonics so as some of you suggested that will be the first thing to go.




No, it shouldn't generate harmonics unless you are saturating the core, in which case it would
get hot.  But the optimum balun in that case would be 1 : 1 current balun.

I use something like this, with some surplus #43 cores that I found locally.

It isn't difficult to build your own using the existing balun core.



Quote

...Now I see prices ranging from $30 for a 4:1 Undilla balun to over a $100 in the DX eng catalog. Is it a you "get what you pay for type thing"?



There are some poor baluns out there.  Look for one that gives you a plot of R and X over frequency.



Quote

Also someone mentioned I could possibly rewind the balun in the tuner to make it a current balun but is there anyway to know if the core is inferior or not? Its about 2.5" outside diameter so it would be a shame to chuck it ...unless its junk.



Probably still usable, but if you have an analyzer it isn't difficult to determine the ferrite type.

A 4 : 1 voltage is typically wound with a pair of bifiliar windings.  If you just reconnect the ends
you can make a 1 : 1 current balun without needing to rewind it (though you'll have to check the
balun performance vs. frequency.)




Quote

... I do have an antenna analyzer but have not yet figured out how to hook it up to ladder line...



I use one of these:





Does your tuner allow you to run straight through the balun?  That's a good starting point.  If it doesn't
permit you to use the balun without going through the tuner part, then in place of the jumper wire on
the back between the balun terminals and the "single wire" pin, use a jumper wire with a banana plug
on the end and stick it into the "COAX 1" or "COAX 2" ports.  That allows you to run straight through
the balun to the analyzer (though there will be a bit of impedance transformation in the process.)
« Last Edit: December 24, 2017, 11:05:47 AM by WB6BYU » Logged
KC1GCG
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« Reply #13 on: December 31, 2017, 11:02:43 AM »

Thanks Don and Wb6 - great info and advice.
I'll buy a 1:1 from DX just to be able to "git er dun" .
I am also going to call/email  Amidon and get some advice on what to buy as I have been wanting to learn to make my own baluns for a while. Watched the vids etc but just find their website rather new user unfriendly but that may just be me and my brain:).
No way on the tuner to use the balun and bypass the rest but thanks for the info on all that. Looks like some good experimenting ahead of me and I have some vids and websites bookmarked already on how to use my analyzer to test baluns etc. Again more fun stuff!
Happy New Year to all and I cant thank you enough for taking the time and sharing all your knowledge. Best regards
K1JRF John
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WB6BYU
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« Reply #14 on: December 31, 2017, 10:04:08 PM »

Quote from: KC1GCG

...No way on the tuner to use the balun and bypass the rest...




Of course there is, the same way I do it with my 949 tuner.

Instead of jumpering the balun to the "single wire" post, put a banana plug
on the end of the jumper wire and plug it into COAX1 or COAX2 instead.
Then you can use it either direct or through the tuner using the bypass
option for that port.
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