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Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 903
Registered: 9-2004
| | Posted on Wednesday, November 30, 2005 - 10:39 pm: | 
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i started this thread to help my friend coyote with a particular problem he's having, but i imagine others have experienced this same phenomenon so i hope this helps.
coyote, i was reading through the Amateur Radio Handbook today, and i ran across an interesting paragraph pertaining to the broadcast interference thing.
from what i read, this problem exists when you have an issue with your grounding system radiating as an antenna, thus picking up all kinds of broadcasts its not supposed to.
so, would you indulge me by detailing the specifics of how your station is hooked up? i would need to know EVERYTHING in order to troubleshoot this properly, so be very detailed and include all the stuff you're sure i wont care about.
(if we get this solved, you should have much better ears!)
it could also be the older radio just giving up the ghost, but i think you mentioned this happening with other radios you had. were these occurences also at your current location?
as for the stingy meter, here is a fix i have used many times and it works great! you must be careful, but if you are, you really cant mess up.
after all, the meter doesnt work right now!
first, you might need to unsolder the two wires and remove the meter from the radio. (most of the time you do) mark the wires so as not to get confused later. you will notice that the meter is two pieces of clear plastic held together with some clear tape. if you carefully remove the tape, the two halves will come apart. after you have removed the front piece, you will notice a very small set screw at the base of the needle. sometimes there is a piece of tape over it, but you can just poke a hole in it. no need to remove it. you MUST use the right sized jewelers screwdriver for this screw or you will strip it.
when you have the right screwdriver, turn the screw about 1/4 turn to the right, and then 1/4 turn to the left. DO NOT TURN MORE THAN THIS
its important, but not hard to control if you are patient. you will probably notice that when you first try to turn the screwm that it is stuck. after you break the initial "stick", you are just turning it back and forth a bit to loosen it up.
when you feel that the needle is moving freely, (you will feel it) turn the screw so the needle sits EXACTLY on zero. put the meter back together, reinstall and enjoy!
i have only run across one meter that this did not work on, and it just would not move freely. i had to replace it. the worst case scenario here is that you put the meter back in the radio and it works the same as before.
you will likely want to readjust the S meter pot inside the radio after doing this, as the first thing most people do when their meter stops working is turn it back and forth. just use a known good radio to get it set right.
good luck! |
Coyote
Advanced Member
Username: Coyote
Post Number: 611
Registered: 11-2004
| | Posted on Thursday, December 01, 2005 - 7:37 pm: |
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Matt,
$$$ is the key to a good system, which I have very little of to be used on radio equipment and used some things, like the antenna mast, that were already in place. The antenna itself is over 30 years old and probably needs to be taken apart and the oxidation removed. (aluminum Archer 5/8 ground plane,} this was done a year and a half ago before the antenna was put back up after being in storage for close to 20 years.
The grounding system is probably not the worlds best. The 8' copper rod would only go in about 5'. Tennessee is on a lime stone slab and the soil is extreamly rocky,especially on this hill I'm on, so that was as far as I could get it in. Even pounding with a 10 pound sledge for 15 minutes didn't get it in any farther. I have 10 gauge wire from both radio, amp, freq. counter running to a copper strap that is grounded to the rod with the same guage wire. The antenna base is also grounded to the same rod as well as the ground for the lightning arrestor. I am running approx. 130' of RX8 coax which at the moment runs up the wall in a corner, into the attic, (my lower floor is basically under ground) out the back wall, across the back wall (the electric service box, phone service, and AC unit are all on this wall) then it run's underground to the mast for about 4'. The mast is only 25'. I have a TV antenna about 6' under the radio antenna. The TV antenna is only used if we have severe weather and the sat. dish stops working.
My plan is to eventually move the entire radio antenna to just outside the wall which would only be 20' from the radio and would greatly shorten my coax run, and a new ground rod and new mast or tower if I'm lucky. The TV antenna would remain on the old mast in its present location.
The "broadcast" interference does not happen regularly, and when it does, its usually a good indication that some decent DX is about to happen, or at least thats how it has worked out in the past. I've only had it happen two other times before the past one that I can remember and one of those times was with the Teaberry but the rest of the system was as is now.
As for the meter, it moves fine when I transmit, it just dont move much when a signal is being received. Its really not that big a deal I guess, as long as I can hear them, I really don't care what kind of signal they put on me, just makes giving them an accurate signal report hard. Someone may have already messed with the S-meter pot, like I said before, it was "tinkered" with a bit before I got it.
Now, the meter trick MIGHT work for the Cobra 148GTL that the meter don't want to move on, but then again, the meter might also be broken on that radio. (only gave $10 for it and it works OK other wise)
I do however appreciate your time and wanting to help out and any suggestions that I can do to improve will be taken into great consideration and dependent on the YL's pocket book.  {re-read first sentence)AND considering the fact that this weekend, I had to help a friend of the YL's move, so I removed the tool box from my truck to make more room to haul stuff, which is also what my antenna is mounted to. Well, to make a long story short, the antenna broke in the process. I am getting a new one tomorrow.  but had to wait all week to do so because of the almighty $, which we don't have much of.
Later,
CEF-443
Stu |
Wildrat
Intermediate Member
Username: Wildrat
Post Number: 400
Registered: 12-2003
| | Posted on Thursday, December 01, 2005 - 10:45 pm: |
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When they want a report, just do what I do, I say " Man your puttin 10 pounds on me, sounds like your in my living room with me " trust me they will be happy. If you don't like telling little white lies, get yourself a scale and put your foot on it and when they start talking put your foot on the scale, you might be surprized, as will they when you tell them your putting 50 pounds on me.
Wildrat
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Coyote
Advanced Member
Username: Coyote
Post Number: 615
Registered: 11-2004
| | Posted on Thursday, December 01, 2005 - 11:46 pm: |
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WildRat, that's pretty much what I do now. If they have strong audio, thats a 9 for sure!
CEF-443
Stu
MENC |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 913
Registered: 9-2004
| | Posted on Friday, December 02, 2005 - 12:23 am: |
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coyote, i know exactly what you mean about money being the deciding factor in a 10-8 station.
your setup is just fine. i can tell you one thing for sure though, unless that lightning arrestor is a polyphasor, you need to take it out of line.
it causes a big impedence bump by having the sheild connected with a wire to the ground rod. if the arrestor was actually mounted to the ground rod, this might not be a problem. either way, if its not a polyphaser, it wont keep your equip. from frying anyway, so why use it.
with a coax run as long as yours, you need to make sure that it is not radiating a signal and isnt picking up any either.
make sure the total length of wire from the back of your radio to the ground rod (strap included) is no longer than 6 feet.
the main cause given for broadcast interference is AC line pickup, meaning that your AC system is acting like an antenna.
you could build a line filter and install it in the radio, just splice into the cord. they are very simple and very cheap to build. (like, two coils made of enamel wire and two or three disc caps). if you want to make one i'll tell you how.
the other way to isolate your radio from the AC line is to find a big piece of ferrite and wrap the AC cord around it a bunch of times making a nice tight coil and taping it up. ( i do this on all my radios) the piece of ferrite i use comes from a shortwave radio kit that rad shak used to sell) it will look like the kind you find inside an old AM radio but will be bigger, like the size of a pencil but bigger around).
the cool thing about trying these suggestions isnt so much getting rid of the occasional broadcast interference, but getting rid of noises and static that you have just learned to live with.
also, the 5 foot ground rod is OK, just as long as you cut the excess off so the whole thing is underground. any portion of the ground rod that is above ground is not only doing you no good, it is likely radiating a small ammount of signal.
so, try these things out when you have some free time (i know!). they wont cost you more than about $5.00 and might just make a big difference.
matt |
Coyote
Advanced Member
Username: Coyote
Post Number: 620
Registered: 11-2004
| | Posted on Friday, December 02, 2005 - 9:39 am: |
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Matt, Thanks. Now that you have posted I now KNOW of problems. My ground line is a bit longer than 6', it is almost the same run as the coax. Like I mentioned before, my radios are located basicaly underground in our front room. While the front of the house is on ground level, the side walls of that room and the main floor are underground. Can I put a different ground rod out side in the front to ground the equipment to and ground the antenna to a seperate one? I thought all the grounds should go to the same rod, with the electric service rod being the most desired location.(not an option without hiring an electrician to come out and put in a new one since the exsisting is located under a concrete slab)
I did cut off the excess ground rod as it would have been a major hazard when mowing.
I also imagine I am picking up a great deal of AC line noise with these long runs of coax and ground wire. A reinstall of the antenna closer to the station would probably help a great deal and I could shorten my ground line to say... 15'... or I can install a seperate one at the front of the house and then the run would be within the 6', but I'd have to find a way through the front wall which is a probably 6 to 10 inches thick. (natural stone front with cinder block backing it up on the entire front of the house)
Since I have been on this forum I have made improvements from the original set up as best I could with what I have to work with. Moving the antenna will be my next priority next spring and I may have to live with what I have till then. Like you said, I've learned to live with it and the noise level is really not that bad, until the kids turn their computer on and then I have tremendous interference from it on either ch. 16, 15, 14, 13 or 12, but just on those channels and its not on all of them, it varies, strange I know and has driven me nuts ever since I discovered this as being the source of this god awful interference. I often have to make them shut it down on Sundays just so I can hear during the Net. None of the other two computers in the house, both of which are within 7' of the radio, one being right next to it, interfere at all.
For now the set up will remain as is and I will gather items needed through out the winter months... polyphaser, new ground rod, new antenna mast (or tower if I'm lucky) maybe new coax.... anything else?? I may have a little money to play with after Xmas or maybe at tax time, although I really need a newer truck and tax time was going to be slated for that.
I will try some of the other suggestions as time permits and the materials are available. Have'n four boys ages 5, 10, 13, 16 leaves very little time or money for much of anything, and with Christmas REAL close and these bigger kids wanting BIGGER more expensive "toys"... well... one wants Xbox, just received a new Telecaster for the 13 year old yesterday, the 10 year old has shown an apptitude for play'n drums, so we are try'n to get him a set.... yadda yadda yadda... (now I'm just venting ...
I'll stop now... ttyl and Thanks a bunch Matt.
CEF-443 |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 921
Registered: 9-2004
| | Posted on Saturday, December 03, 2005 - 10:40 pm: |
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so you're forming your own band eh? a good friend of mine who's a drummer is just about to have his second daughter, and he's decided to start an all girl band! he says he just seems to have the genes for it!
coincidentally, i am one of four boys in my family. no sisters. oldest to youngest is 34, 31(me), 29, 24.
i know EXACTLY what you mean about the toys getting more expensive. we never had much money growing up, and when you wanted something expensive, you went and found a job.
as for the station; im really glad that sinker started asking questions because i needed to get my grounding facts straight.
we'll describe the "dream" setup, and then you do whatever you can do whenever you can do it. you actually have some things going for you in your current location.
ever heard of pounding in a ground rod sideways?
it actually works much better than having it vertical because it covers a bigger area of the ground.
as long as its far enough underground so that it would be just below the ground in the front of the house it will work great!
so picture this: (if possible) drill a hole in the wall behind the radio desk just a few inches up from the floor. pound a ground rod sideways into this hole, attatch ground strap to rod, and run individual 10ga. wires to the equip. this should keep those 10ga. wires less than 4 feet long. then run a 10ga. (or bigger) wire from the sideways ground rod, to the AC service box, and attatch it to the ground wire coming out of the box. i use a ground clamp that you can get at lowes. try to run this wire as horizontally as possible and keep it near the ground as much as possible. (not critical) then run another wire from the AC box ground along the ground or just under it to the mast ground rod, and then the mast ground rod connects to the mast or a wire running up the mast to the base of the antenna.
this way, you can get rid of that darn lighting arrestor which i hate. you can just use a barrel connector instead. the big deal with the less than 6 foot rule is just about the wires coming out of the radio equipment getting to a ground rod before the length of wire reaches 6 foot. the length of wire between ground rods doesnt really matter.
as for the interference, do the offending computers use a wireless mouse or keyboard or joystick or anything else wireless. lots of computer wireless systems operate on ch.14 (27.125mhz) and will bleed all throughout that area.
hope my suggestions help, and let the kids pound in the ground rods! gotta get sumpin' outta' 'dem kids!
merry christmas to you and all the family, i feel like im getting to know them,
matt |
Wildrat
Intermediate Member
Username: Wildrat
Post Number: 413
Registered: 12-2003
| | Posted on Sunday, December 04, 2005 - 6:36 pm: |
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Picture this three ground rods for the polyphaser and equipment. Three ground rods for the tower, then connected to the main ac service ground system which is two more ground rods, back to the other end of the house where the polyphaser is also connected to the sub ac service ground system. Then a whole house surge protector on the circuits for the cb equipment and computers. I think I have enough grounds. When we get the pool enclosure built I will connect all of this to the ground for the enclosure. It'll be a heck of a ground plane.
Wildrat |
Coyote
Advanced Member
Username: Coyote
Post Number: 627
Registered: 11-2004
| | Posted on Sunday, December 04, 2005 - 10:32 pm: |
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Matt,
Yeah, I imagine at some point a band will form from all this. I'm going to get a new bass as soon as possible. I started out play'n bass and miss have'n one around. I'm hope'n my oldest boy will pick it up and start learning. I know quite a few other guitar players around here but no one play's bass, so I need to get back in practice.
I don't think drill'n a hole in the wall for the ground rod would be possible. One right outside on the other side of the wall yes, and a ground strap through a hole in the wall would be possible. Then I could run to the service box ground line.
None of our computers use wireless anything. We did have one wireless mouse/keyboard one time, but it didn't work very good and got rid of it. It's the computer itself. I thought maybe it was the monitor causing it, but I turn the monitor off with the computer still running and the interference is still present. Turn the computer completely off and its gone. Its so bad that it interferes with the radio in my truck sitting in the driveway. I'm hope'n to replace that computer sometime real soon and that should take care of the problem.
When I do finally get around to move'n the antenna, I will get rid of the arrestor for sure and go with a poly phaser. I'm already in the planning phase for the move this spring and can hopefully start buying the equipment little by little and install bits and pieces and make the final move in the early spring by moving the antenna to a new mast/tower. I think I can live with what I got till then. I can still make decent contacts as it is, so I'm fairly happy with it but would like to have it as near to perfect as possible on a budget.
Once again, thanks for take'n the time Matt. It is much appreciated. We WILL make that first contact soon, I can feel it. IT WILL HAPPEN.
CEF-443
Middle TN Coyote
MENC |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 925
Registered: 9-2004
| | Posted on Sunday, December 04, 2005 - 11:10 pm: |
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i was sure i was going to catch you on 38LSB today at about 5pm your time. i heard two different stations from TN and made a couple of calls for you.
oh well!
catch you on the air stu, introduce those young'uns to the brilliance otherwise known as Led Zeppelin!
then you'll have a band!
later,
matt |
Coyote
Advanced Member
Username: Coyote
Post Number: 629
Registered: 11-2004
| | Posted on Monday, December 05, 2005 - 8:35 am: |
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Matt, well, you know how today's kids are, they like the new stuff. The 13 year old has been working on some AC/DC, Zep and Floyd...
hummm.. lets see... 5pm my time.. I was on there, might have been on 13lsb though... Not sure what part of TN you were getting, probably the western side as I didn't hear anything come'n out of the west coast. It was all northern. It'll happen soon, I can feel it.....
later
Stu |
Rldrake
Junior Member
Username: Rldrake
Post Number: 26
Registered: 1-2006
| | Posted on Tuesday, January 17, 2006 - 6:42 pm: |
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Oh, where to begin here. Everything so far under this topic is a mixture of misconception of basic and fundamental concepts of RF, the 3 types of grounds,CB myth and old wive's tales.
Lets start with the misconception that PolPhaser is the only way to go for a so-called "lightning arrestor"...Although PolyPhaser does offer an excellant, very effective, and well engineered product...they are by no means, whatsover, the only way to go. There are dozens of manufacturers offering equally as good or even better products. A couple that quickly come to mind are Alpha Delta Communications and DX Engineering. There are dozens of others. All of them, including PolyPhaser, are very effective as atmospheric surge voltage protection, static buildup from wind, blowing snow and sand, and even corona discharge. They all also do a good job of protecting your station from EMI produced by nearby lightening...either ground to earth or cloud to cloud. None of them will offer any protection from a direct strike. If a direct strike does occur, radios at your station would be at the very bottom of a list to be concerned with. "Arrestors" are made that will have a good chance of protecting against direct lightening strikes, but will usually be found at commercial broadcast stations and a few sw broadcast stations. Such protection systems are very expensive...cost easily exceeding the median cost of most homes in the continental United States. Such systems are not usually found at the transmitter sites of the local FM broadcast station. Such systems will more likely to be found at 50,000 watt (erp) AM broadcast stations and at sw broadcast stations such as VOA...or the universal Time Standard/Frequency Standard stations such as WWV and JJY. Okay, now on to a CB myth...the one about the coaxial, unbalanced feedline picking up undesired signals. The truth is that feedlines, whether unbalanced (coax) or balanced (twin-line, open wire feeder) do not "pickup" signals, whether desired or undesired, at all. The exceptions to this basic fundamental is, as in the case of a coaxial, unbalanced feedline, would be if the sheilding on the feedline was severely damaged, if the rf connectors (such as pl-259s, type Ns, BNCs, etc.) were of inferior (totally junk) quality or much more likely, improperly installed...or had worked themselves lose. Or if the feedline was manufactured with horribly inadequate shielding (in which case it would not even really be "coax" at all). In the case of balanced feedline (300 ohm twin lead, 450/600 ohm ladder line) it would only receive such signals if the line were severely damaged, or some condition, as to put it into an unbalanced state. Neither feedline type, balanced, open wire or unbalanced coaxial, is going to "pickup" a signal regardless of how long it is...doesn't matter if it is 3 inches long or 30,000 miles long...or anywhere in between. Quick Note: If using an unbalanced, coaxial type, feedline at a run of 130 feet...especially at high HF frequencies from 15 meter up to 10 meter wavelengths...a low loss feedline should be used...Real RG213 type or better. Now onto another misconception: The deal about the so-called "ground" bringing in some sort of unwanted interference. One must be able to understand the differences between the 3 types of grounds...Electrical safety ground (mains), RF ground, and static/EMI ground (so-called lightening ground). The electrical safety ground is provided, if the electrical service at the station, and the power supply itself (120v AC to 13.8 V nominal) is up to National Electric Code standards, at the elecrical outlet (the ground terminal on the wall outlet). An RF ground is unnecessary, and even more so totally undesirable, at any point other than right at the antenna itself ! Examples of RF ground only at the antenna, where it belongs: Vertical antennas...vertical, ground mounted ideally fanned out radials, evenly spaced separation, at least as long as the height of the antenna. The more radials the better up to 120 in number (may be staked to the ground or buried just below the surface). Next example: Elevated vertical...usually a 1/4 wavelength or higher above the ground (surface of the earth)...Radials required: at least 2. Three or four is the norm. If the elevated vertical is designed and assembled correctly, any more than 4 radials yields nothing better in performance. Radial length for the elevated vertical should 1/4 wavelength long + about 5%. There should be a set of radials for each band to be used...in the case of 11 meter (27mhz) CB, the radials should be about 10 feet long...reasonable variances in radial length is fine. The radial lengths need not be precise lengths, just in the ballpark. If antenna feedpoint impedance is high (over say 70 ohms) the radials can be lowered, or bent, downwards to lower the feedpoint resistance (ohms RF resistive). If lowering the radials to achieve 50 ohm load, or thereabouts, do not lower the radials any lower than 45 degrees to the vertical radiator. These radials are the RF ground...at the antenna where it belongs. Final example of a proper RF ground at the antenna, where it belongs: The Dipole...the most commonly used antenna for 2-way radio communications in the world...comes in many, many flavors...a few being: conventional (flattop), vertical (hard to feed properly), sloper, Vee, inverted Vee, Yagi directional (beam). Basic dipole consists of 2 elements, each 1/4 wavelength long...fed in center, most commonly with RG213 unbalanced feedline (coax). Dipole is great for multi-band operation when very, very low loss open wire feedline (usually 300 ohm twin lead or 450/600 ohm ladder line) cut for lowest frequency to be used or longer. Total length of such dipole for muti-band use 160 meters up to 6 meters (1.8 mhz up to 50.0 mhz)is 264' to about 300' or so. Length here is not critical as long as both legs are within reason of being equal in length. Depending on the frequency dialed up the swr on this antenna will be anywhere from 1.1:1 to 20.0:1 or more (that's 20 to 1 swr, not 2 to 1). The great thing about this antenna system is that even with the high swr, there is very, very little RF power loss since the open wire feedline is virtually loss free...even at feedline length runs as long as a thousand, or even more, feet. A pretty good deal to when one considers the cost of feedline...about $70 bucks for a hundred feet of RG213 (213 is closest thing to what is now called RG-58...Real Rg-58 hasn't been made since the late 1960's...what now is marketed as RG-58 type cable, nowadays, meets no particular specification other than the outside diameter of the insulation jacket). 450 ohm balanced feedline (ladderline)runs about $16 dollars for a 100 foot length. 100' of 1/2" hardline (50 ohm coax, low loss) runs about $200. 7/8" hardline costs a little over $600 for a 100' length. Hmmm....Interesting, but not at all surprising, the $16 per 100' balanced feedline which is virtually lossless is about 1/4 the cost of the more expensive RG213 unbalanced feedline with its quite measurable loss. Hmm, again...the $16 per 100' foot length of virtually lossless ladderline is almost free as compared to the $600 per 100' very low loss even at high swr, yet still very measurable, 7/8" inch hardline. Gee whiz, it seems that the multi-band dipole, fed with open wire, virtually lossless feedline even with its extremely high swr, has less rf power loss and actually radiates more rf into the air than the narrow banded 5/8 wave single band vertical (with its again lossy matching network at its base, as all 5/8 wave verticals do). All this with no RF ground besides the rf ground being at the antenna (the "ground" leg of the simple dipole). At the antenna only...where it belongs! Now for a little fact about when an RF ground in the shack, or just outside the shack, would be desirable...it would be when feeding the antenna with no feedline at all. in other words, using random length wire or a longwire type antenna. Now is the time that the RF ground right at the station would be necessary and/or desirable. But wait now, lets think about this a little...well what do you know about that...our little long wire, or random wire, antenna is right here at the station as is the RF ground. The RF ground is right at the antenna WHERE IT BELONGS. Golly, it almost makes one wonder if those silly, old hams had a little something figured out back then, 100 years ago...Way back in the day before anyone even dreamed up the term swr (standing wave ratio). And now a final little note to end this story...those ol' radio experimenters, back 100 years ago during the Ice Age never really had much of a problem , as they developed the basic fundamentals and theories of radio through experimentation, observation, and plenty of math work, with such things as all the problems associated with ground loops...the reason being they didn't go around trying to put RF grounds where they did not belong...AWAY FROM THE ANTENNA. They put the RF ground only where it was needed...AT THE ANTENNA. |
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