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IMAX 2000 - Results w/GPK? Balun? Mast Isolation

cominatyalive

cominatyalive

Active Member
Aug 10, 2009
123
3
28
60
Zion, IL, USA
Was reading the closed thread from Wire Weasel on the Imax 2000 antenna.
A lot of good info for sure as I just put one of these antennas up about a month and a half ago. As with everything else, I usually don't screw with something unless there are problems and I went ahead and installed my 2000 up on my house 59' total in the air without a Balun, GPK, or mast isolation.

Well, from the git go & currently, I have about 1.5 db worth of ground floor noise, and interference from what seems to be my power mains from the power company's main feed into my home and from my circuit box as well.

Today I removed my ground cable totally from my mast & unhooked my ground from my equipment. Still the noise. Like a 60Hz hum. I took the coax off the radio as well. It did not hum, but there was still a bit of static.

I installed a 20amp EMI filter in the circuit before the radio, still the noise. But I don't know if this filter is even doing anything. Still the noise.

Anyways, getting to the point here, I am about to go all out here and install a RF choke Balun using a 8" X 3 1/2" PVC pipe, a GPK kit, and better coax. I am going from a RG8X mini coax to a better quality of LMR-400. I am also going to use a two foot Delrin rod to isolate the mast.

I will be doing all of this in the next week or so as long as the weather permits here. I am posting here in hopes of providing my testimonial of evidence of improvement or not. We will see.

For anyone who cares to keep track of my efforts here & my documentation, please feel free. I have another current posting in the CB Radio forum ( Crackling 60Hz hum every third channel) I suppose I should have posted here from the start, But at the time, and currently, cannot yet provide a pin-point in the disturbing hum I have everyday through my Base Station. 1 DB worth of ground floor noise mixed with what seems to be a 60Hz hum from my house mains.

I have already tried many things to pin point this trouble. I will share all my results, (If any) with all. Here is the link to my main post in the other forum. Please feel free to add your two cents worth. And that is no joke.

http://www.worldwidedx.com/cb-band-...hannels-row-every-4th-channel-clear-bell.html
 
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You have a lot less noise on your IMAX than I do - and I wouldn't trade this antenna for any other for the money spent. You have the same problem with your setup that I do - I'm too close to the power lines. I live with it, and it is OK. Could be a lot worse; I have a friend that lives close by me that gets 20 S-units on noise that comes and goes!!! No Joke. If I have between 1 to 3 S-units of noise floor - it is a lot better that having 20 S-units!!!

Don't blame the antenna or yourself. What kind of power supply are you using? Or radio? Power supplies that have weak filter capacitors are going to leak 60 cycle hum. So - have you tried another power supply? Or a different radio - just to figure it out?
 
Hello Rob,

In regards to your noise, I suppose I should count my blessings. Yes, these antennas are really sensitive to picking up noise, but I believe there are ways around it.

Yes, I've tried everything, Even used a car battery to get around my AC power. Still the hum or buzz. I have a power supply, but only use it on my Cobra mobile.

I'm using a President, Zachary T. Base station unit. It has been restored & gone over, everything new or refurbished in it. It's really a great radio. But still the Noise.

I just sold my Cobra 139 base station & the noise was there also. It's even on my mobile when using the power supply or the car battery, makes no difference at all.

I shut off all my circuit breakers in my house except the one my CB is on. Still the hum. Nothing fazes this hum at all & I can't get rid of it.

I am starting to conclude it is the mains or a ground loop I am not aware of or my antenna picking up the power lines as you stated sounds more of what it is actually. But the power lines are not throwing out any frequencies.

I use a AM transistor radio to detect AC noise, works great. So far, the only noise that matches what I hear is the house mains noise.

Anyways, I'm hanging in there.

Keep me posted on your efforts as well. We need all the help we can get.



James
 
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If you are certain that the noise source are the power lines; then you can complain to the power company. You can! Remember; that this noise also affects wireless computer usage. The power companies are required to service poles that have either noisy transforners and/or insulators that give off excessive spurious RF. My friend that has the 20 S-units of noise has done this - and the power company is still in the process of making several repairs locally for these reasons.

The noise is something that I put up with. This antenna and radio setup I use -this year- has allowed me to talk all of the way to Alaska, Hawaii, and everything West of the Rocky Mtns. Even Mexico and Canada - w/o using linear power. I have no complaint with this antenna. It is often the enviorment that affects the usefulness of any antenna setup - Ham or CB...

Edit: Some people that I know have used handheld CB/walkie-talkies to get close to the loudest interference to find the source. Maybe someone you know has one. I used my car/CB radio and drove around my neighborhood to find the noisiest source. I didn't have to go far; it was much worse across the street from me. The transformer was the source of my RF noise!
 
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Installed the GPK kit a few days ago on my Imax 2000. To be honest, I can't really tell if there is a difference or not. The noise floor seems to be a bit lower on the db meter, around 1 db on the higher stations to 1.5 or more on the lower channels. 5, 6, etc. I'm still getting a hum in my radio from the mains, but it's less noticeable on the upper channels. 10 & on up through 40.

Worth the $50.00 dollars?, well, my Imax is 60' total height. I think it has helped a little. I have no results on transmitting yet.

I have other things to try yet. I have a home made RF balun choke & better coax to install soon and I'll let everyone know of my results. I still as of yet to isolate my antenna also from the mast, for what it's worth.

Every little bit of progress will make a difference in the big picture.


Good luck to you guys with your Imax's.
 
Oh, and one more thing.

The bracket for the GPK is a flimsy piece of chrome plated steel. The tips of the bracket bowed as the radials moved around after tightening the bolts. I've yet to see it last through the winter. If the Balun doesn't work either, I may just get another antenna altogether. But I'm really trying to be a believer in the 2000 as long as I can. It's not really that bad of an antenna, but the ground noise is horrible & from my experience it is susceptible to a lot of interference.
Other than that, it transmits just fine.

Food for thought.
 
ihad a imax 2k and switched to a alummumin antenna.sirio2016.it doesnt pick up
all the noise and actually now im able to hear stations i couldnt hardly hear due to noise
heres anther test completely shut off all power to house and get in mobile and see if ya have any noise.if so drive around and find it.heres some culprits for this
1]touch lamps with various light settings
2]dusk to dawn lights outside when on at nite]
3]broadband router either yours or even just from a close neighbor[ive experienced this]
 
There's no way around it, noise IS. There are things you can do to reduce that noise, and it sounds like you are in the process of getting there. The other bad thing about all this is that there are no 'standard' ways of getting rid of noise in every situation, every situation can be different.
Just from what I've read here, it sounds like the noise problem may be from the electrical line. It isn't that hard to 'clean' on line in your house, or just one device on a line. You are doing that with that power line filter. The problem with that is that the noise besides being 'conducted' can also be 'radiated'. You sure could have 'cleaned' that one device's power line, but is it also picking up that noise from the other lines in the house radiating it? Lots of possible sources. Only way to stop that is by putting one of those filters closer to the source, or at the meter to the house. You really don't want to know what those things cost! (Or that delrin :))
Good luck!
- 'Doc

(I doubt if I'd like it either, but 1.5 dB of noise really isn't much. The only times I've ever seen lower than that (or as low as that) has been when I've been completely away from town.)
 
You're right, I shouldn't have used 'dB', should have just rounded things off and said 1.5 'S' units. I don't think I can distinguish 1.5 dB by my 'S' meter, that's what 1/4 of an 'S' unit? It's not like this was any sort of 'exact'. Oh well, col day, belly's full, think I'll take a nap.
- 'Doc


if anything happens that's going to affect me directly, somebody wake me up. If I'm snoring, it better be important. You've been warned. OOOoo! A bug! I think I'll chase it!
 
W5LZ said:
You're right, I shouldn't have used 'dB', should have just rounded things off and said 1.5 'S' units. I don't think I can distinguish 1.5 dB by my 'S' meter, that's what 1/4 of an 'S' unit? It's not like this was any sort of 'exact'. Oh well, col day, belly's full, think I'll take a nap.
- 'Doc


if anything happens that's going to affect me directly, somebody wake me up. If I'm snoring, it better be important. You've been warned. OOOoo! A bug! I think I'll chase it!
Click to expand...

Yes, as a seasoned ham the responsibility is greater than ever to help others along the correct path. That's seasoned ham. Get it?
 
Thanks guys for the tips.

As I mentioned, I have another thread in CB radio. Titled "Crackling 60Hz hum every three channels"

There you can see that I've already came so far in the noise issue. Yes, HotRod, I did turn all the power off for the whole house, I hooked a car battery and went to DC. Still that noise. Like a 60 Hz hum from the power line outside going into my meter.

It's not so bad anymore since I grounded my mast to the Neutral service ground rod for the house. Just a little better. This weekend I was finally able to install my RF choke balun, & my thicker "LMR-400" coax. I also have a GPK kit now installed as well. All explained on my other thread. Check the post.


http://www.worldwidedx.com/cb-band-...hannels-row-every-4th-channel-clear-bell.html


I also have pictures of my progress, the Imax, the balun installed & the GPK in my profile picture album. Please help yourself to them.

As soon as I get another darn PL-259 to solder on, I will be giving out all of my results, (If any) and findings.

73's!
 
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UPDATE 12-11-09 AC NOISE ON ALL CHANNELS!

OK guys, listen up.

The AC hum is back again on all channels for the last two days.
And I have went back to square one again to free my mind of doubts.

First, the noise sounds like a high power crackling hum. For the last two nights & days, it has been horrible. But one thing I have noticed, that when someone else transmits (Talks), Their transmission is clear. As soon as they un-key, the noise right away again.

So I went back to square one & hooked my spare car battery up again to my base to see if it was coming through my circuit, ( the AC line from my breaker box in the house). This circuit is soley dedicated just for my base unit.

But still this horrible, crackling, AC noise!

So I ruled out that the noise was incoming into my radio from the (outlet) or circuit from my Breaker box. In other words, it is not my AC power feeding my radio.

There has been a severe cold snap here near Chicago for the last two or three days now, 4 degrees F. day & night. The ground is frozen. So I thought, would this be a restricted moisture saturation on my ground rods causing the stray power noise not to be dissapated into the ground?

Which in turn would cause my Mast's ground cable & coax ground to become an AC radiating antenna for my Imax to pick up this trapped AC hum?

So I quickly went and unhooked my grounds from the ground rod of the house. But still the noise. 3.0 s units of pure AC crackling hum!

This was at 2am last night. Then all of a sudden around 3am, it reduced to just 1.5 s units on all the channels. Just all of a sudden it got alot quieter, but it did not go away totally. But it is bareable again.

This my friends is purely a reception problem. AC noise being picked up by my IMAX 2000. Could it be from my power lines from the pole in the back alley coming to my house at the top of the eves. Where the power lines hook to my house is only a mere 25 feet or so from my antenna.

I noticed when it has been warmer outside, it was never this bad.

At this point, I know it is not the power feeding my radio. It is coming through my antenna. Should I call the power company?

OK, now it is 3:15am and channel 28 & 29 are only at 1.0 s unit of noise while channel 7, 6, & 5 are 3.0 s units of AC HUM! I also noticed that channels 1,2 & 3 are also much quieter. But at 2:00 am ALL CHANNELS WERE 3.0 S UNITS OF PURE AC HUM FROM H_LL!

Some days, when it was warmer, the noise was totally gone.


OK, that's enough for now. Does anyone got a clue? Does anyone else have this sort of problem? And again, if you want to do some reading of all of my efforts, I have another post in the CB Radio threads

Here is the URL again for those who have like 20 hours to read it all.

I dare ya!

http://www.worldwidedx.com/cb-band-...hannels-row-every-4th-channel-clear-bell.html


PS: This noise sounds like high voltage power lines to me. Maybe it's time to call Com ED.

James
 

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