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Post by BladeRunner now OLD FLASH!!!!! on Jan 29, 2009 19:51:32 GMT -5
Over the past few months that I have read and read and experimented with my antenna system and it has been pretty much determined that my problem is front end loading. I greatly improved my issue by loading my coax down with about 25 to 30 Ferrite Collars and the problem is much better but not gone. So , Round 2....The Balun. I has been suggested by many and I have done much reading about baluns. This is one subject that there is virtually no agreement on even within the same paragraphs on the subject. The length of wire suggested is from 18 to 21 feet with the perfect length being 25 feet ...LOL There have been no solid theory on coil diameter or length. I just have to happen to have a piece of RG8U, about 24 or 24 feet in length. I had a heavy duty Jug that Window Washer for Auto's come in.I wound 21 feet of the cable closely and tightly around the bottle I used wire ties to secure the coax to the bottle and then sealed it with clear packing tape. I added PL259 connectors to each end. Would it be important to attach the balun to the mast using stand off's to isolate (as much as possible) the coil from the mast? Do baluns work with any great efficiency? Do they work at all? I will be mounting this as closely as possible to the PL259 female connector on the gamma match. Will the coil possibly change the tuning of the antenna by a small amount? large amount? Any other suggestions welcome short of buying a 100 ft tower with stacked Yagis...LOL Seriously any ideas and suggestions are appreciated. If it's not worth doing.stop me now.......You guys have a great day and some day I hope to be as helpful to you guys as you have been to me so far.  Pic of my ugly balun |
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Post by bob85 on Jan 29, 2009 21:40:21 GMT -5
bladerunner, info on coaxial chokes is pretty well documented in the arrl and similar publications, the common pitfall is people find info on hf baluns that require more turns than is optimal @27mhz, the arrl suggests about 6.5 feet wound 6-8 times solenoid fashion like the one you made there, longer lengths with more turns degrade choking performance at 27mhz, heres an article you may want to read, www.k1ttt.net/technote/airbalun.htmlgood luck. |
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Post by Deleted on Jan 31, 2009 0:02:00 GMT -5
That ugly balun with the PVC couplers in mine. I am KC2NXV.
I think with CB, you only need about 6 turns. I have about 10 turns on that one, for the lower bands.
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Sandbagger
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Post by Sandbagger on Jan 31, 2009 13:56:18 GMT -5
That ugly balun with the PVC couplers in mine. I am KC2NXV. I think with CB, you only need about 6 turns. I have about 10 turns on that one, for the lower bands. That's right, 6 to 8 turns will do the job. More than that is better for the lower frequency bands, but will start to lose effectiveness on 10/11 meters. |
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Post by BladeRunner now OLD FLASH!!!!! on Jan 31, 2009 22:28:01 GMT -5
Al right then. I'll cut back about 1/2 the turns I have and put her up tomorrow and we'll see how it works. I appreciiate all the help. Thanks all.
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Post by Deleted on Feb 1, 2009 9:28:17 GMT -5
I had my friend mount one on a bean, using black UV ty-raps. he used my style with the PVC couplers. I am thinking the milk jug might be too big for mounting it that way, but it might work. The PVC one will mount nice and sturdy.
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Post by BladeRunner now OLD FLASH!!!!! on Feb 1, 2009 16:26:16 GMT -5
THe jug mounted nicely. it didn't raise the swr nor did it help the front end loading situation. Will try iit for a while longe before I will make my final determination.
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Post by Junior on Feb 1, 2009 22:22:53 GMT -5
Never heard of front end loading! If you mean front end overload, that is a radio receive issue. turn down your rf gain. LOL
JR
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Sandbagger
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Post by Sandbagger on Feb 2, 2009 8:10:16 GMT -5
Never heard of front end loading! If you mean front end overload, that is a radio receive issue. turn down your rf gain. LOL JR Now that we've had this discussion about baluns, I have to admit that the term "front end loading" is not one that I'm familiar with. A coaxial balun is typically used to minimize coaxial radiation, which helps in those cases (such as running a radial-less stick antenna) where poor decoupling and coax radiation causes significant near field RFI issues. |
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Post by Marc on Feb 2, 2009 10:37:21 GMT -5
What I think Bladerunner is trying to eliminate is Front end over load.
Where a TV or Stereo receiver Has inadequate shielding in part if the audio amp section.
So what happens is that RF gets into the amp. This is more than likely a proximity(distance from the antenna to the TV or stereo receive) issue not a product of a dirty signal.
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Sandbagger
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Post by Sandbagger on Feb 2, 2009 12:56:13 GMT -5
What I think Bladerunner is trying to eliminate is Front end over load. Where a TV or Stereo receiver Has inadequate shielding in part if the audio amp section. So what happens is that RF gets into the amp. This is more than likely a proximity(distance from the antenna to the TV or stereo receive) issue not a product of a dirty signal. That's sort of what I assumed, as that makes the most sense.... |
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Post by Marc on Feb 2, 2009 13:10:32 GMT -5
Not a lot you can do at that point.
1. Move Antenna farther away. (if you can)
2. I have seen on one or two cases if the receiver has a good solid metal case add a ground wire to a earth ground (does not help on very many cases maybe one out of 100)
3. Go higher (if you can)
4. move receiver farther away from the antenna. (if you can).
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Post by BladeRunner now OLD FLASH!!!!! on Feb 2, 2009 17:17:34 GMT -5
Marc
I appreciate all the suggestions. None of the 4 is possible right now. They will when summer gets around. The problem isn't bad , I'm just trying to eliminnate it completely I'm going to move the antenna as far from the house as possible.
Thanx
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Post by Marc on Feb 2, 2009 17:36:12 GMT -5
Sounds good also try to get up a little higher if possible
Distance plus height equals better angle.
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Post by BladeRunner now OLD FLASH!!!!! on Feb 2, 2009 18:09:06 GMT -5
The weird is that I think it has burned somthing out on my DirecTV amp. THe mornings after I get on and talk. I have to do complete reset on the HDTV receive or the the sound takes about 10 minutes to go from zero volume out from the amp to 100 % expected ( from the coxial digital sound out) The analog and HDMI sound come out from the second it comes on. If i do a factory reset first No problem. Would adding ferrite collars to the coax inputs from the dish to the receiver inputs help?
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Sandbagger
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Post by Sandbagger on Feb 2, 2009 18:14:27 GMT -5
Marc I appreciate all the suggestions. None of the 4 is possible right now. They will when summer gets around. The problem isn't bad , I'm just trying to eliminnate it completely I'm going to move the antenna as far from the house as possible. Thanx How much power are you running? Is this happening with 4 watts, or are you amped up? If you're running power, you might have to consider backing off a bit to reduce the RFI. |
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Post by BladeRunner now OLD FLASH!!!!! on Feb 2, 2009 22:20:08 GMT -5
If I backed off any more , I'd be legal..LMAO....Thanks
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Post by BladeRunner now OLD FLASH!!!!! on Feb 2, 2009 22:30:42 GMT -5
Looks like I have the problem completely solved. After i added the balan I didn't have to much to test with . Today I removed all the excess speakers from myhome theater and left just WHt was necessary. I talked for a while ..slowily cranking the power up . At no time did I have any feedback, or squeal or picture interruption through the Sat receiverat all. I have my finges crossed I have the issue do;ved completely
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