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Hello all,
I'm a newbie here so take it easy on me please. It's been 30 years since I've had another base station. But I've finally have one up now and just getting back into it. Bare with me but I have a few questions here. I have this annoying problem with this crackling, buzzing, 60 hz noise coming through the receive on every channel except every 4th channel which is clear like a bell. Every three channels in between, (For example - 5, 6, & 7 has this horrible buzzing, with a little crackle & a hum which is definately sounding like a 60 hz hum. I have been inestigating this with an old trick of using a AM transistor radio and walking around the house. Low & behold I have found many sources with this trick all over the house. My wireless modem for my computer network here was the worse. A couple light dimmers, A few wall warts and these new Black & Decker bug repellers that you plug into your wall receptacles. Needless to say, the Modem transmit frequency was even going down the Earth ground cable to the water pipe. But after turning off the Modem, It was gone from the Earth ground cable, but the noise was still coming out of my CB. In fact, I have turned everything off in the house except the CB. Still this 60 hz hum three channels in a row and one clear channel before & after the three noisy ones. As for my radios, I'm using an old Cobra 139 base & a mobile cobra 29 ltd classic. Same noise on both CBs. With the Mobile, I'm using a Pyramid Gold Series power supply. With the supply running & the classic ltd on, I get the noise. When I turn off the CB with the power supply still running, the noise goes away. No noise from my supply at all. I have not tried hooking a car battery up yet, but I will soon to see if it's actually my mains from the cicuit box, or if it's an antenna related problem. For an antenna, ( which I regret buying now ) a Solarcon IMAX 2000, I have no ground radials yet, but it seems to be working well at 60 ft total height from the ground. I have grounded the bottom of the mast with a 50 ft 8 gauge stranded copper wire down to it's own 8' copper ground rod pounded into the ground. It is in the ground about a foot away from my neutral ground rod from the power mains. I suspected 60 hz hum leak to the mast's ground rod, so I unhooked the ground cable from the mast, still this horrible buzzing 60 hz hum. To furher complicate my post, I even went as far as holding my AM transistor radio 2" from the main power lines right before they enter my house through the rafters, little noise to my surprise, (with my wireless network modem off mind you) hardly any noise at all, not like what's coming from my radios. So it's turning out that my mains was not as noisy as I thought. I'm at my wits end for clear reception. Has anyone here had this sort of problem? My SWR is a good, solid 1.4 no matter what weather I am having here. My transmit seems to be ok considering what a couple locals have told me with a radio check. 9db or so at 15 miles or more. Is this normal for my old radios to buzz this 60 hz hum? One last thing before I close, I noticed both of my radios have SO-239 female bracket type connectors for my antenna hookups mounted on both radios which is the norm I'm guessing. Alligator teeth all around the diameter of the connectors. But my coax has the PL-59 connectors with just the two locator nothes on the male connectors on both ends of the coax. Is this normal? I can't see how in the world they are being bonded flush when screwing them together. Shouldn't my connectors on my coax be of the same match as the female one's mounted on the back of both my cobras? Well I've visited many CB online suppliers but no Male SO-239 plugs at all, mmmm I must be missing something here. For all I know my connections are not good enough in this type of hookup scenario? Sorry for the book I've written here, but I'm deperate. Anyone care to take a stab at me? Stab away. 73's

It may sound to simple but sometimes you can just unplug the radio from the wall turn the plug over and plug it back in. I have fixed the problem you are having several times in the past this way. That is as long as the wall receptacle isn't one with one large and one small opening.

skipper1

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strange sounding problem indeed.

i was thinking faulty crystal until you said you had the problem on two different radios.

does the 3 channel noisy, 4th channel clear scenario continue all the way through the 40 channels?
how is your reception on those clear channels?
how is the transmit on those channels?

just a guess here, but you might try connecting the ground rod for your antenna to the ground rod for your house with a suitable sized wire.

NEC codes state that all grounds should be tied together.

another possibility is that the source of your noise is not even in your house.
do you live near a restaurant?

i used to live within a couple of blocks of a certain steakhouse chain, and i would get 5-7 S units of noise only on channels 5 and 13.

i traced the problem down to their paging system.
it was the type where they hand you a "pager" and it beeps when your table is ready.

there was really nothing i could do about it so i just didnt use those channels.

as for the coax thing.
it is advantageous to have just the two "prongs" on the male coax connectors.
those two prongs will always sit within two grooves on the female connector.
just wiggle the male connectors a bit and get them seated before you start screwing them on.
you will feel them "seat" when its right.

what kind of coax are you using?
where did you get it?
did you install the connectors yourself?
are they the crimp on type or are they soldered on?
can you unscrew the threaded ring from the connector and slide it back down the cable?

where is your antenna mounted in relation to your house?
how many feet of coax are you running and what path does it take from the antenna to the house?

im thinking that you might have some cheap, or nicked coax, and it could be receiving these spurious signals.

oh, just one more thing.
reading your post as one huge paragraph is a bit difficult to do.
you might try to put some spaces in there.
makes it easier for us to read.
just a friendly suggestion.

good luck,
hope we can help you,
LC

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"Man shall never reach the moon, for such a quantity of gunpowder would be needed as to gravely injure the crew."
~ Children's Encyclopedia, 1926

First I'd like to thank Skipper1 & loosecannon for their efforts, I really do appreciate it. But things have taken a huge turn tonight for the worse. Before I go on to tell you, I will add that yes, I did figure that the two notches was just the way things were with the connector ends of my coax. I have been feeling them notch into the SO-239 connectors while tightening them up. And I will hook my mast's 8 ga ground cable back up as soon as I can, but as you were saying Loosecannon, to hook it up to the house's ground, to which ground should I attach it to? You see, from what I know, the majority of the residential houses here in my area all have two grounding points even though they are both bonded together in my mains box of the house.

Hook it to the common neutral ground from the mains just outside my meter box?, or the Earth ground to my water pipe in the basement? I am guessing you are referring to the Earth ground? as the Earth ground is the one dedicated to Lightning strikes if I'm not mistaken. Also, as for the noisy channels, I was wrong, they hum and crackle through all the channels. But there are a few clearer channels such as channel 8 or 10 or the low 20's. But 5, 6, & 7 are the noisiest animals I have ever heard in my life. I'm also getting blips & beeps coming through my speaker. Ok, before I go any further, getting back to the (Big left turn discovery). I went and bought a new battery for my caravan today just so I could use the old one for my Cobra 29 ltd classic mobile radio to see if it really was a noisy mains from my house power.

Well, lo & behold, I AM STILL GETTING THE SAME DISTURBING NOISES! with the car battery. Which now tells me that I am picking the noises up soley through my IMAX 2000 piece of crap antenna. But as beaten down as I am now at 3:10am in the morning crying over this horrific humming & crackling, I am now suspecting the neighbor woman's wireless modem transmission signal or some kind of house alarm or something coming from her house. What else could it be? It's not my modem, cause I unplugged it and stopped the transmission signal. Heck, like I was saying before, I even turned off my whole house except the breaker for my CB. So I was hoping it was my mains instead of my antenna picking up some garbage. But still the noise mind you. Looks like I'm screwed & tattood now for sure because this woman is the nosy type & a couple months ago I had to put her in her place. There goes any kind of communication with her right out the door. What do I do now to keep my antenna from picking up this interference? It turns out, my house power & wiring is just fine.

Even if I'm running my flourescents, modem, and bug repellers. Yes, they do put out noise as I found out with my AM transistor radio, but that's not the culprit. I am receiving interference from somewhere close by my house through my antenna. And I'm convinced of it now. PLEASE! if there is a GOD! would someone please tell me my next step because I'm out of solutions. Do I make a ugly balun on my feed line? A choke? would it help? Is my antenna prone to this interference because I have no ground radials on my antenna? There really can't be too much else I can do here is there? Oh yeah, before I forget, another piece of bad news tonight. I just discovered that my PAL WATT/SWR stand alone meter box will no longer let me set the SWR indicater before I switch it back to SWR to get my reading. Yesterday it was fine. When I go to preset the indicator (on set) it stops an inch before the set line. However, on my Cobra 29 ltd has no problems setting with it's built in indicator or getting my reading, in which my CB still says about 1.4 for my SWR. HELLO???? GOD????? ARE YOU STILL THERE? PS: oh, I forgot to space out my paragraph so I'm editing it now, look better? perhaps I should be a writer. Gots to be better luck in that as I'm having here. 73's ???? Not tonight I'm afraid.

I just had a thought, should I now move this post to the Forum for antennas? Just kidding.

Three things worth trying to eliminate the noise are:

add radials to your antenna and isolate antenna from mast,

add an rf choke/line isolator at the feedpoint,

ground the unbalanced (coax) side of the choke.

sounds like common mode currents are the source of your problems.

Thanks Jazzsinger,


Well, after I got some sleep last night, "like a good whopping 4 hours worth", I started to think about my problem some more. But now in the terms of what could I do to prevent interference. I was going to put a Balun at the feed-point when I installed the antenna. But I read somewhere that it's not good practice to go ahead with a ton of things if nothing is wrong. But now that something is definitely wrong, I have been thinking about doing it. Problem is, that I am running 75' of coax already. Getting back to what Loosecannon was asking about my coax, it's the cheap stuff, RG8X or U or something. It's gray and only as big in diameter as a regular cable tv cable. I wanted the bigger, thicker stuff, but the salesman asked if I was running low power & said that should be fine. The connectors are PL-59's and do not slide all the way back down the cable. Also, I do not have enough length to put a Balun in place with just 75' of cable as I am just making it in through the wall to my Radio. From what I have read about Baluns is to make it so you do not have to cut your existing cable, right? I want it all in one piece all the way from the antenna to my Radio. Looks like I will order better cable and add another 10 ft or less for my Balun/choke. To what Jazzsinger mentioned about isolating the antenna from the mast, well, it's a very good idea, but isn't the coax ground from the coax connector going all the way to my radio as well? However, I do see how eliminating the extra 10' of mast from the antenna would better my chances of avoiding interference though, so I'm going to try it. I've also been planning on getting a radial kit for my antenna soon also. But would this help eliminate the interference? or just magnify it? As Radials are for bettering reception right? Well, I feel a little better today knowing there are still some avenues to explore. That's what I enjoy the most, learning from mistakes, learning, and hopefully conquering obstacles such as this interference problem. Although, I have also come to a place to where I may just have to accept that I may never be able to eliminate this problem and just have to only use certain channels. Sad isn't it? That some people just cannot have their particular hobby without some hi-tech interference problem from a neighbors house alarm or modem or who knows? I feel infringed upon. Well, I will keep this post going as long as I'm investigating it & trying to solve this. I welcome any & all comments to this post. 73's

Since you have a battery on the radio now, turn off the mains to your house. If the noise goes away, then it is somewhere in your house. Just turn on one circuit breaker at a time untill you get the noise. Then just look at what is on that circuit.
Rich

I have the same problem and it's in the house one block west of me and I suspect it's a bad fluorescent ballast, just waiting for it to go poof.

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I U 212

cominatyalive,

im not an electrician, but the NEC codes for all grounds being tied together means exactly that.
all your grounds should be tied together.
if there is a ground rod in the ground near your power box, attach the ground rod for the antenna to it.
if the ground wire from your power box goes to a cold water pipe, then attach the ground rod for the antenna to the cold water pipe.

do yourself a favor and read up on grounding, RF interference, and lightning protection as it relates to radials.
there is a LOT of info out there on the net to sift through, but eventually you will know what you need to do.

lightning protection is a tricky thing for us radio guys.
we can actually make things worse in our efforts to protect ourselves.

i agree with your hypothesis that its something in the neighbors house that is causing your interference.

the first thing i would try would be moving the antenna to the other side of the house temporarily to see if that makes any difference.

isolating the antenna from the support structure, using the groundplane kit, and using an RF choke at the feedpoint are all good ideas, but they may or may not be enough, so its up to you to decide how much money you are willing to spend on this experiment.

as for your question about the coax providing a path to ground when you isolate the antenna from the mast; yes, you are right, it still does.

you have to remember that we are dealing with two different types of ground here. we have DC ground, and RF ground.
two entirely different beasts.
i will leave it to you to investigate this on the internet, and just give you the practical solution here.

1. get the antenna as high in the air as you can. the further the antenna is from the interference source; the better.

2. isolate the antenna from the mast and install the groundplane kit.
this type of antenna needs a counterpoise to work against.
if there is no groundplane, the antenna will use the shield of the coax and the mast for a counterpoise.
the groundplane kit goes a long way towards being a suitable counterpoise, but its not quite enough, and some currents will still be induced into the mast and the coax if they are not isolated. the way to isolate the mast is to use a teflon or delrin rod a foot or two long, mount it to the top of your mast, and mount the antenna to it.
the way to isolate the coax is to use the RF choke at the feedpoint.

then you run the coax down the mast to your ground rod and ground the shield of the coax there for lightning protection. a good device for this is called a polyphaser.

get the best coax you can afford.
something with dual shielding will help.
doesnt have to be the big thick stuff.

for your situation, i would recommend LMR-240. it is the same size in diameter as the cable you are using now, but is double shielded which really helps with noise, and its just an awesome coax cable. very well made.

find someplace to get it from that will install the PL-259 connectors on the cable for you. make sure they use AMPHENOL connectors and that they solder them on properly.

your IMAX is a good antenna but you need to give it a fighting chance.

if i were you, i would start with the better coax, the groundplane kit, and moving the antenna if its possible.

if those things dont help enough; then you can move on to other solutions.

good luck,
LC

__________________
"Man shall never reach the moon, for such a quantity of gunpowder would be needed as to gravely injure the crew."
~ Children's Encyclopedia, 1926