| Author |
Message |
    
Charliebrown
| | Posted on Tuesday, February 03, 2004 - 3:09 am: | 
|
which antenna is better, the i max 2000 or the maco v 5/8 antenna? i know there is a difference in power, one is 1500 watts and the other is 5000 watts. both antennas being 5/8 wave i guess it really comes down to aluminum antenna verses the fiberglass antenna. i have the a-99 antenna which is a good antenna, but i am looking for something better in gain, without going to a beam antenna. |
Tech833
| | Posted on Tuesday, February 03, 2004 - 4:24 pm: |
|
The Maco is slightly better than the Imax due to the dielectric loss of the Imax fiberglass radome and lossy coils in the base. However, the Imax is far easier to tune. The Maco is less neighbor friendly. |
Charliebrown
| | Posted on Tuesday, February 03, 2004 - 6:50 pm: |
|
thanks mr. tec 833 for the info. as always i value your information you give us on these questions that are asked of you. also thank you for your time you give us. |
Twa77
| | Posted on Tuesday, February 03, 2004 - 8:21 pm: |
|
what do mean by less neighbor friendly. is that
less friedly do to tvi
or
less friendly as far as looks go.
if you say less friendly in the tvi aspect then you are going against what you have been pushing for quite some time " antennas don't cause tvi"
. there are quite a few who claim the fiberglass ones are the ones that "splatter" i can't honestly say if this is true or not. i have an imax and it gets into the neighbors tv. i dont know if it would be better or not with the maco as ive never used one.if it helped to have a maco i would have one in a heartbeat.
however if you were refering to neighbor friendly as far as looks goes , i totally agree with you.
tony
cef 153 |
Kc0gxz
| | Posted on Thursday, February 05, 2004 - 1:41 am: |
|
Charliebrown
Well, fiberglass in itself doesn't cause splatter. But, particular wavelengths do. The A-99 for example is notorious for splatter BECAUSE of its design AND wavelength. Not because it's fiberglass.
As far as comparing the two antennas you mentioned in your post, they both have their advantages. Personally, I prefer the I-Max because of it's 24 foot length and its very usable wide bandwidth capabilities. NOTHING outbands it. NOTHING.
So, if you're running a CB radio with a few "extra" frequencies, the Maco V is a great antenna and hard to beat. But if you're running a 10 Meter radio with a few hundred frequencies, the I-Max with its wide bandpass would be the way to go. There is no noticable difference in the gain of these two antennas.
By the way. The Maco V can handle an advertized rating of 2000 watts of RF power and the I-Max can handle a claimed 5000 watts. So, just how bad can the coils in the I-Max really be? The I-Max is a far, far better improvement over the A-99.
Jeff, kc0gxz. |
Charliebrown
| | Posted on Thursday, February 05, 2004 - 6:03 am: |
|
mr. kcogxz, my last question is there very much gain the max 2000 has over the 99? the reason that i ask this is i have seen some different specs. on the antennas. for example, some say the max has only 5.1 dbi gain, others say 5.1 db gain. the 99 from what i have seen is suppose to be 3 to 3.3 db gain. if the max is 5.1 db gain then i will get the max antenna. now if the max is 5.1 dbi i dont think i would see enough improvement if any over the 99. if you have seen the different info on the max like i have then you know how confussed one could get trying figure if the max would have enough improvement over the 99 to be worth spending money on. some of my freinds tried the change and some say no improvement and that they could not tell any improvement between the 99 or the max. can you shine any more light on this subject? if so thanks. |
Tech808
| | Posted on Thursday, February 05, 2004 - 6:50 am: |
|
Charliebrown,
PLEASE, read the Articles that Tech833 has taken so much time to research and write on these antennas to help the Copper Forum Member's choose an Antenna.
You will find all of the answer's to your question's.
Go Two TOPIC'S down from this TOPIC on the Forum Here to the Subscriber (Preview) Area.
Then Click on Articles
Then Click on How to Choose a Ground Plane Antenna
Read this Article.
Then go to Product Reviews
and read the Article's written by Tech833,
A99 Exposed and IMAX2000 Exposed
This should supply you will all of the information you need to make your choice.
Hope this helps.
Lon
Tech808 |
Charliebrown
| | Posted on Thursday, February 05, 2004 - 9:15 am: |
|
thanks fellows for your help. there is a lot of antenna hype out there and with all of them being over rated so they can make a sale it makes it hard to get the true facts. once again i thank you all for your help. |
Pig040
| | Posted on Thursday, February 05, 2004 - 11:20 am: |
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I prefer the aluminum antenna, just by virtue of using the whole aluminum antenna as opposed to the wire that runs up the 2000, or 99. Also the 99 and 2000 have in my experience been Bleedsticks. |
Bullet
| | Posted on Thursday, February 05, 2004 - 7:57 pm: |
|
charliebrown,
your right, they all lie about gain. as we all know the first lier hasnt a chance.
ive seen antrons advertised at 9.9dbi of gain and the imax at 12dbi gain. about that of a 4 elem beam.
when the 99's fall short of a dipole's gain and the 2000 a little better.
if you want gain in a "omni/vertical" then you want a collinear. |
Kc0gxz
| | Posted on Saturday, February 07, 2004 - 5:14 pm: |
|
Charliebrown
Bullet is right. All antenna manufacturers lie about the gain on their antennas.
Real life down-to-earth gain on ANY CB antenna isn't much to brag about. Factual Db gain on these antennas is a long ways away from the manufactures claims.
Here is the closing statement from Tech-833 when he did the testing on the I-Max. And lets not forget the fact that he is a professional radio engineer and has designed and built many commercial radio sites around the world. When he speaks, we should listen. The following were his thougths on the I-Max as compared to the A-99 taken from the Subscriber (Preview) section under "Product Review". There is some VERY interesting and well written material there. Everyone should spend some time in that section. I find it very educational.
--------------------------------------------------
CLOSING STATEMENTS: In summary, the Imax 2000 is a very well built and well thought out antenna. It's ironic that the Antron 99 paved the way for this antenna, but the Imax 2000 is head and shoulders above the Antron 99 in engineering practice. So much additional inductance coil is needed in the Antron 99 to get the highly capacitive 1/2 wave element tuned. However, in the Imax 2000, with the .64 wavelength element, the capacitance is much lower, which requires much less inductance to tune it out. Therefore, much less coil is required to tune the Imax 2000 to resonance, which greatly reduces the coil losses.
So what is the TRUE gain of the Imax 2000? Assuming a .64 wave shunt fed dipole in free space, minus the losses associated with the series capacitance and inductance, and minus the necessary counterpoise, according to my math, the Imax 2000 has 2.9 dBi gain. That is to say, the Imax 2000 has 2.9 dB gain on the horizon over an isotropic radiator. Referenced to a center fed 1/2 wave dipole, which is the industry standard, the Imax 2000 has a gain of 0.8 dB. This could also be stated as 0.8 dBd gain. Although adding the Antron GPK-1 ground plane kit will not add much gain to the Antron 99, the ground plane kit would add significant gain on the horizon for the Imax 2000. A .64 wavelength radiator is much more efficient and will have a much lower angle of radiation (keep the signal down on the horizon instead if wasting it up in the sky) with a proper counterpoise system. Adding the GPK-1 to the Imax 2000 (according to my math and previous .64 wavelength test range plots) will result in a 0.3 dB gain improvement. This will bring the Imax 2000's actual gain up to 3.2 dBi or (1.1 dBd).
-------------------------------------------------
I would like to add something here.
When looking at a "dBi" rating, you have to remember that this is from an antenna that doesn't exist on this planet. Personally, I ignore dBi ratings. But on the other hand, dBd ratings DO exist in real life. In reality, ALL antennas should be compared to a dipole antenna.
The reason why you see such highly inflated manufacturers dBd and dBi ratings on their antennas is because they know that most people are ignorant when it comes to real specs of a given antenna and will actually believe such hype and spend their money on them. In other words, high "dBi" ratings on antennas "SELL" antennas.
One thing you can take to the bank though. NOTHING (other than a beam) out-performs a 5/8 wave omni-directional antenna when its base is mounted at least one wavelength (36ft) from ground level. NOTHING.
Copper sells 3 of the greatest antennas ever offered to the 10 Meter Ham and Cber.
1- The MACO ALPHA V,
2- The MACO V-5000, and
3- The SOLARCON I-MAX 2000.
You can't go wrong with any of these antennas.
I personally prefer the I-Max over the others because of its 24 foot length and its great bandpass.
Jeff, kc0gxz. |
Charliebrown
| | Posted on Sunday, February 08, 2004 - 3:38 am: |
|
jeff, that answers all the questions i have on this subject. looks like a max antenna will be my next choice. and i always listen to mr. tech 833. it would be a big mistake if someone did not listen to him and mr.808 and the other techs. thanks. |
Legend
Junior Member
Username: Legend
Post Number: 11
Registered: 12-2002
| | Posted on Wednesday, March 10, 2004 - 4:49 am: |
|
Dear techs:
Please help me out here.
I have a Sirio 827 5/8 wave aluminum ground plane antenna. The one with the 8, 4 and 1/2 foot radials. A really decent antenna, actually.
It has always been an excellent antenna, but ever since I moved into the place I live now, I have had a number of strange anomalies occuring with it.
Here is how it is set up:
It sits atop a 40 foot telescopic push up pole, extended to 36 feet. The top of the antenna is roughly 58 and 1/2 feet. I have the antenna mounted the way it was designed to be mounted, with it slid over the end of the pole, and the bolts firmly tightened for a good connection to the pole. The pole is grounded at the base with 3 six foot copper coated rods linked together.
I have 60 some-odd feet of Belden RG-8, foam insulated coax (8214) leading to the shack, with a perfectly flat SWR, but only after having trimmed it to be in phase with 27.185 as it's fundamental frequency.
(yeah, I know about the coax trimming arguments, but I am able to make sure my amp sees a 1:1 SWR, as well as my radio by doing this)
At any rate... here is my quandry. I have terrible time with man made noise in my receive. It is NOT the radio, because my shortwave (Drake R8A), as well as any other radio, has the identical problem, when hooked up to this antenna.
The strange part, is when I unhook the outer connector (shield), the noise drops totally out. It used to be the opposite when I lived anywhere else. The noise would drop out (a GOOD thing!) whenever I would CONNECT the outer connector. Now it is nice and quiet when it is DISCONNECTED, but incredibly annoying with it CONNECTED.
Now, let me ask this:
I am going to place a few ferrite split beads (73's, right?) on the coax just below the antenna base, to eliminate any stray RF current flowing back down the coax. I was also wondering... I am doing the right thing by having the base of the antenna coupled directly to the supporting mast, and then grounded at the bottom of the mast, right?
By the way, my antenna gets into EVERYTHING when running anything more than minimal power. Phones, T.V.'s, stereos, ect...
Is it a good possiblity that this could be being made worse by RF current coming back down the outer coax? Are there any other beneficial places to put RF choke beads on my system? On the coax just as it comes out of the amp, for example? Maybe on the jumper just as it exits the radio perhaps? And will adding an RF balun (split-bead type) to the coax at the base of my antenna, help to make my SWR meter READINGS (not ACTUAL SWR) less dependent on exacting coax lengths?
If any techs could please answer as many of these questions as possible, I would be very grateful. I really want to put these issues to rest.
Ohhh... and one other brief question. My SWR's tend to suddenly jerk up and down a small amount, but only on windy (or even mildly breezy) days. I have checked the coax and connectors, and they are in prime condition. I have also checked to make certain that the antenna segments are screwed together nice and snugly.
What is the most likely reason that my SWR's flutter like that in the wind? I know that it's the antenna, but I'm not sure what part. I am thinking about taking it down and putting machine screws and nuts through each segment fitting to make absolutely certain that there is a rock solid continuity.
At any rate... thanks for fielding so many questions... lol. I just want to get this thing straight, once and for all.
Thanks again!
LEGEND |
Twa77
Intermediate Member
Username: Twa77
Post Number: 109
Registered: 1-2003
| | Posted on Wednesday, March 10, 2004 - 5:16 pm: |
|
sounds to me if you fix one problem you may just have fixed them all. i think your right you have a loose connection somewhere causing swrs to fluctuate. also generating tvi. thats my story and im stickin to it
|
Tech808
Moderator
Username: Tech808
Post Number: 1759
Registered: 8-2002
| | Posted on Wednesday, March 10, 2004 - 5:28 pm: |
|
Legand,
Off hand I would suggest looking at / checking your PL259 Connector's on your COAX.
Make sure that BOTH of your PL259 Connector's are SOLDERED GOOD to BOTH the SHIELD & CENTER STRAND of your Coax and that you have NO SHORT's.
Lon
Tech808 |
Highlander
Intermediate Member
Username: Highlander
Post Number: 444
Registered: 12-2001
| | Posted on Wednesday, March 10, 2004 - 7:33 pm: |
|
Does that antenna have a coil at the feedpoint? I had a 5/8 wave vertical that got damaged in that coil section that caused similar problems. |
Legend
Junior Member
Username: Legend
Post Number: 13
Registered: 12-2002
| | Posted on Wednesday, March 10, 2004 - 8:56 pm: |
|
Well, my questions were basically ignored, except for the very last one, which was the one I was least worried about.
My antenna had the same slight SWR flutter (on breezy days) with a totally different coax hooked up to it, so I know that it is the ANTENNA, as opposed to the coax.
I'd really like to get some answers to my previous questions, if possible. Thanks in advance.
Legend |
Tech833
Moderator
Username: Tech833
Post Number: 579
Registered: 8-2002
| | Posted on Wednesday, March 10, 2004 - 9:45 pm: |
|
I have a Sirio 827 5/8 wave aluminum ground plane antenna. The one with the 8, 4 and 1/2 foot radials. A really decent antenna, actually.
** All the ground radials less than 8 feet long serve no purpose other than for looks.
It has always been an excellent antenna, but ever since I moved into the place I live now, I have had a number of strange anomalies occuring with it.
Here is how it is set up:
It sits atop a 40 foot telescopic push up pole, extended to 36 feet. The top of the antenna is roughly 58 and 1/2 feet. I have the antenna mounted the way it was designed to be mounted, with it slid over the end of the pole, and the bolts firmly tightened for a good connection to the pole. The pole is grounded at the base with 3 six foot copper coated rods linked together.
*** How far apart are the rods? They should be at LEAST as far apart as they are long. If not, they cancel each other out.
I have 60 some-odd feet of Belden RG-8, foam insulated coax (8214) leading to the shack, with a perfectly flat SWR, but only after having trimmed it to be in phase with 27.185 as it's fundamental frequency.
*** Trimming should not have been needed. That is indicative of a problem.
(yeah, I know about the coax trimming arguments, but I am able to make sure my amp sees a 1:1 SWR, as well as my radio by doing this)
*** Like I said...
At any rate... here is my quandry. I have terrible time with man made noise in my receive. It is NOT the radio, because my shortwave (Drake R8A), as well as any other radio, has the identical problem, when hooked up to this antenna.
*** That Drake is a nice radio. I am jealous.
The strange part, is when I unhook the outer connector (shield), the noise drops totally out. It used to be the opposite when I lived anywhere else. The noise would drop out (a GOOD thing!) whenever I would CONNECT the outer connector. Now it is nice and quiet when it is DISCONNECTED, but incredibly annoying with it CONNECTED.
*** I already know why... I'll go further before I answer.
Now, let me ask this:
I am going to place a few ferrite split beads (73's, right?) on the coax just below the antenna base, to eliminate any stray RF current flowing back down the coax. I was also wondering... I am doing the right thing by having the base of the antenna coupled directly to the supporting mast, and then grounded at the bottom of the mast, right?
*** Ferrites are not going to fix it. Yes, the antenna should be grounded to the mast at the top (mountingpoint). You can also ground your coax shield right at the base of the mast to help possible TVI. That is the most effective drain available.
By the way, my antenna gets into EVERYTHING when running anything more than minimal power. Phones, T.V.'s, stereos, ect...
*** See above. And below.
Is it a good possiblity that this could be being made worse by RF current coming back down the outer coax?
*** No.
Are there any other beneficial places to put RF choke beads on my system?
*** Not in this case or for your intended purpose.
On the coax just as it comes out of the amp, for example? Maybe on the jumper just as it exits the radio perhaps? And will adding an RF balun (split-bead type) to the coax at the base of my antenna, help to make my SWR meter READINGS (not ACTUAL SWR) less dependent on exacting coax lengths?
*** No.
If any techs could please answer as many of these questions as possible, I would be very grateful. I really want to put these issues to rest.
*** The problem is likely a loose connection which is causing intermod in your system. I work on these all the time. Heavily populated radios sites have this problem a lot. Securing everything with Penetrox and bonding everything with copper wire will solve most problems at sites. The loose connection is microscopic, small enough to actually rectify RF like a diode. You may find it is nothing more than some corrosion under a screw in an element or coil connection.
*** This is the one area where I believe fiberglass antennas are far superior to aluminum ones.
Ohhh... and one other brief question. My SWR's tend to suddenly jerk up and down a small amount, but only on windy (or even mildly breezy) days. I have checked the coax and connectors, and they are in prime condition. I have also checked to make certain that the antenna segments are screwed together nice and snugly.
What is the most likely reason that my SWR's flutter like that in the wind? I know that it's the antenna, but I'm not sure what part. I am thinking about taking it down and putting machine screws and nuts through each segment fitting to make absolutely certain that there is a rock solid continuity.
*** That may solve everything.
At any rate... thanks for fielding so many questions... lol. I just want to get this thing straight, once and for all.
Thanks again! |
Legend
Junior Member
Username: Legend
Post Number: 14
Registered: 12-2002
| | Posted on Friday, March 12, 2004 - 12:00 am: |
|
Tech 833:
I Thank you very much for your time, and effort. Still, some things I'm kinda hazy on...
Quote:
"All the ground radials less than 8 feet long serve no purpose other than for looks."
I've read in numerous Amateur publications, that many shorter radials, is preferable to fewer longer (1/4 wave) ones. Also, I notice that there are many (expensive) amateur vertical antennas made with less than 1/4 wave radials. Are these radials really worthless, or only good for "looks"?
Quote:
"How far apart are the rods? They should be at LEAST as far apart as they are long. If not, they cancel each other out."
I can't help but wonder what percentage of CB/Ham installations have interconnecting ground rods that are 8 feet apart. I've seen a lot of varying opinions in Amateur publications on this. Anything from triangles with 12 inch spacing, up to six feet. "They cancel each other out"? So it would be every bit as effective to have just ONE rod, as opposed to three, if they are not 8 feet apart? Are you sure?
Quote:
"Trimming should not have been needed. That is indicative of a problem."
Well, then I guess I've had the same problem for the last 28 years. I have always been able to help my transmitter see a perfect, or near perfect SWR by doing this, assuming that I have the antenna tuned properly. It becomes even more a factor, when patch cords and other appliances are involved in the equation. My equipment gets hot MUCH slower and to a MUCH lesser degree when I present a perfect SWR to the transmitter, even though I know that trimming doesn't affect the ACTUAL SWR at the antenna.
So... no matter how many people argue to the contrary, and insist that trimming is worthless, I have always been of the mindset: "It helps ME a lot, even if it doesn't help someone else. And it sure as heck doesn't hurt anything."
Also, if it is "indicative of a problem", then what kind of problem might that be? Whatever this problem is, I have had it in every CB station configuration I have been involved with. Sometimes, the coax length happened to be right on the money from the start, but when changed... then whamo. Same effect. I know that damn near every one has this "problem", because most people will acknowledge that their SWR *readings* will change with varying lengths of coax. Not the ACTUAL SWR, but the SWR that their transmitter sees, which is STILL important for efficient operation.
Quote:
"That Drake is a nice radio. I am jealous."
Can't argue with that. ;)
When I said:
"The strange part, is when I unhook the outer connector (shield), the noise drops totally out. It used to be the opposite when I lived anywhere else. The noise would drop out (a GOOD thing!) whenever I would CONNECT the outer connector. Now it is nice and quiet when it is DISCONNECTED, but incredibly annoying with it CONNECTED."
You replied:
"I already know why... I'll go further before I answer."
You never did answer, as far as I can tell. (unless this was it)
"The problem is likely a loose connection which is causing intermod in your system."
This receive problem is one I'd really like to figure out.
In reference to my transmit problem (TVI RFI, ect...), I wrote:
"Is it a good possiblity that this could be being made worse by RF current coming back down the outer coax?"
To which, you wrote:
"No."
So it's not possible that I have any RF coming back down the outer braid from the antenna base? If I did, wouldn't a balun or RF choke help reduce this?
I wrote:
"Are there any other beneficial places to put RF choke beads on my system?"
You responded:
"Not in this case or for your intended purpose."
OK... how about for ANY purpose? What purposes might see some benefit, and where would I place the split beads?
And finally, you mentioned in your reply:
"Securing everything with Penetrox and bonding everything with copper wire will solve most problems at sites."
I'm sorry for my ignorance, but could you be more specific about your meaning? I have never used Penetrox before, or copper bonding. When you say "at sites", are you referring to the union points of the antenna parts? Where can one buy Penetrox, and where do I spray it? On all of the connection points of the antenna?
Again, I apologize for my ignorance. I very much appreciate your efforts to answer my questions. |
Dindin
Junior Member
Username: Dindin
Post Number: 17
Registered: 2-2004
| | Posted on Friday, March 12, 2004 - 9:55 pm: |
|
Tech833,
I read and reread your postings on the Serio antenna and something just dont sound right;"All the ground radials less than 8 feet long serve no purpose other than for looks."
after reading that I would like to see a spectrum analyzer test on this antenna and the effect the different sized ground radials would have(on harmonics).In todays market a manufacturer,in order to survive is not going to let fluff over functionality cut at profits.Those small radials may not cost the manufacturer much,but they do cost him something(profit).as far as looks go,I dont care for the way it looks.Nor am i trying to endorse it for I have not used one.I'm more of a Maco fan.Although my favorites were the Hustler 27JR and Super Swamper,would love to get a hold of either one of those! I do agree on the use of the Penetrox and bonding of all the parts.It may be a regional thing but NoAlox is easier to find around here than Penetrox.sorry about getting long winded but felt I had to add my t.c.w. |
Legend
Junior Member
Username: Legend
Post Number: 15
Registered: 12-2002
| | Posted on Saturday, March 13, 2004 - 1:13 am: |
|
Hi again...
So, where does the Penetrox go? On the joints where they slide together? Like I said, sorry for my ignorance on this, but I've never used the stuff before.
Also, what is meant by "bonding", or "copper bonding" all the parts?
Thanks. |
Bigbob
Senior Member
Username: Bigbob
Post Number: 1745
Registered: 12-2001
| | Posted on Saturday, March 13, 2004 - 9:32 pm: |
|
My opinion on bonding,make up short 1" jumpers of 12 gauge wire with loop connectors and attach to the sections at the joints with stainless steel bolts and lock washers,this bonds the two sections electrically regardless of corrosion in joint,penetrox helps reduce corrosion on metal,there are electrical fields everywhere,and aluminum is subject to corrosion,aluminum is not a pure metal,at least the aluminum we use,it is an alloy of aluminum and magnesium,the alloy produces the nessassary prerequisite for a voltaic cell two dissimilar metals and the corosion(aluminum oxide) the electrolyte add a little moisture and viola a 1 cell battery,bring in the strong electric field produced by overhead lines data transmission lines,home electrical and you have the potential for a very tough problem to solve,make sure every connection is clean and tight,grounds,coax,solder-joints,ground clamps,mounting clamps.I personally have had this problem for years,the overhead lines are 120 feet away but they have many loose connections in the lines,110 years old and the power company just laughs at me when I complain because I'm not a liscenced ham,there is a security light that is maintained by the power company,that causes interference during wet weather it is straight south and that's where I point during the cef net,so you're not alone but your problem may be able to be corrected,sometimes when we corespond to one another we assume the other is at the same level or greater knowledge so sometimes we make assumptions that the one we are talking to fully understands what we are talking about,we assume a common point of reference,so if we sound condesending we don't mean to,I'm speaking for myself specifically and the others on this forum in general.Bigbob |
Legend
Junior Member
Username: Legend
Post Number: 16
Registered: 12-2002
| | Posted on Saturday, March 13, 2004 - 10:30 pm: |
|
Thanks BB...
That was very thorough answer, and just what I needed. Thank you for your time.
I am going to go over my whole system, from stem to stern, just as soon as we get into the good weather. My goal is to make everything as electrically sound as possible, as well as try to eliminate some of these RFI problems.
I am going to put my amp literally 2 feet from the ground rod outside the wall of my radio room, and use the heaviest practical conductor, possible.
Is there any practical use of split torroidal beads anywhere along the coax, other than right at the antenna, which I will ALSO be doing. After the amp, or the radio?
Basically, I don't really care how long it takes. I intend to do as many things as I possibly can to reduce unwanted interference to my neighbors.
Generally, I use the very least amount of power necessary to conduct a conversation. I frequently use 1 watt, or even less. But sometimes, when I'm shooting skip, or when I am talking to someone a long way away with a ground wave, I have to "pump it up" a bit. Obviously, I'd like to keep the RFI potential as low as possible, without having to go house to house, beading everybodies computer speakers, telephones, and stereo speakers. I know that I probably can't COMPLETELY eliminate RFI at my end, but I want to do as much as possible, with MY installation.
If you, or anybody else have an suggestions, or success stories to share, I'd love to hear.
Legend |
Bigbob
Senior Member
Username: Bigbob
Post Number: 1746
Registered: 12-2001
| | Posted on Saturday, March 13, 2004 - 11:04 pm: |
|
To eliminate rfi,the easiest and most dificult,a paradox,is to mount the antenna,at base,60 feet from ground,and put 8 ground radials 36 feet long 2 inches under the soil,12 gauge coated wire,bonded at base of mast or tower,but still use ground rods at base,the rods are for lightning and the radials are for rfi and generated signal,use the smallest diameter split beads you can,the closer the proximity of the ferrite the better it works and yes if you have a long run of coax put the split beads every 8 feet or so it helps decouple generated electrical fields from outside of shield ,for rfi at base of antenna should be sufficient,3 or 4,other than this I don't know,I have to stand back awhile my brain hurts,lol.Bigbob |
Tech181
Moderator
Username: Tech181
Post Number: 874
Registered: 7-2001
| | Posted on Saturday, March 13, 2004 - 11:13 pm: |
|
Legend,
Besides what BigBob said about grounding, and connections, the easiest way to reduce RFI to others is not to spray it around in the first place. Keep the modulation in check and make sure the radio is properly aligned. Your amp will only amplify •••• going into it, so make sure you start out with a clean, tight signal. Garbage in, garbage out.
|
Tech181
Moderator
Username: Tech181
Post Number: 875
Registered: 7-2001
| | Posted on Saturday, March 13, 2004 - 11:16 pm: |
|
Sheesh, the "C" word for the "S" word is not allowed here??? |
Legend
Junior Member
Username: Legend
Post Number: 17
Registered: 12-2002
| | Posted on Sunday, March 14, 2004 - 2:08 am: |
|
I guess they want to run a clean, tight forum...
lol... |
Tech808
Moderator
Username: Tech808
Post Number: 1803
Registered: 8-2002
| | Posted on Sunday, March 14, 2004 - 2:37 am: |
|
Tech181,
The language Blocker is part of the Forum Program.
It is automatically done to a post when any of the word's in the program pop up in a post. |
Tech808
Moderator
Username: Tech808
Post Number: 1804
Registered: 8-2002
| | Posted on Sunday, March 14, 2004 - 2:47 am: |
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Legend,
Yes, We do try and keep it CLEAN and TIGHT as it help's to avoid any possible problem's that may arise.
We try and make it an Enjoyable Site for EVERYONE Including the Copper Forum Member's as well as those who just stop by to Visit the Copper Forum and see what we have to offer.
Lon
Tech808 |
Mr_rf
Intermediate Member
Username: Mr_rf
Post Number: 284
Registered: 12-2001
| | Posted on Sunday, March 14, 2004 - 7:45 am: |
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Legend/others,
For years I have used the concept of ADDING SCREWS where the element sections slip together and weatherproofing the joint on all my aluminum tubing antennas. I have seen too many antennas loose screws and the corrosive effects too.
- I usually add two or more self tapping screws (no black coated screws) and an "inside star" washer to every joint. I place them at 90 degree positions around the tubing and stagger the locations up and down the joint so they bold/bite the tubing at different stress points (see pic).
- Then I usually tape the joints with 3M brand electrical tape, type "Super 88+". Don't pull and stretch teh tape too excessively when wrapping it around, make clean sharp cuts when cutting the tape off, and keep your fingers off the tape as much as possible to prevent contamination to the tape by your body oils...this will improve the tape's lifespan and ability to seal.
Of all the antennas I have done these two things to I have never lost an element nor had RFI due to joint corrosion effects.
Also, Tech 833 is very correct about the shorter ground elements being useless. In fact, if anything the shorter elements would improve the antenna's proformance (resonance) at other frequencies causing unwanted harmonic energy and transmitter noise to increase...this is NOT GOOD!!!!
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Bigbob
Senior Member
Username: Bigbob
Post Number: 1749
Registered: 12-2001
| | Posted on Sunday, March 14, 2004 - 9:06 am: |
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I work with aluminum,t6061-t5 and if you are not experienced it is easy to strip the holes,thats why I recomended stainless through bolts,no.6 but no larger than no.8,if you break one just put in another,but with screws if you strip the hole you must go to a bigger screw,loss of metal means weakening of joint,just dont squish the tube or you will be back to square one,and as far as radials go fabricate a system whereby you can attach 8 nine foot radials to it,tech833 reccomends 8 ground radials 36 feet long 2 inches under soil bonded to base of mast or tower electrically,these must be evenly spaced and this will lower the take off angle of antenna whether beam or stick. |
Legend
Junior Member
Username: Legend
Post Number: 19
Registered: 12-2002
| | Posted on Sunday, March 14, 2004 - 9:24 am: |
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Well darn... now I'm bummed. The Sirio 827 is a pretty pricey antenna, though certainly not as much as the I-10K. I sure hate to just throw the thing away. It's much better constructed than the Maco V58 as far as material quality goes.
Hmmmm... I wonder If I can locate some thin lightweight aluminum tubes that will slide right inside the existing radials. Then I'd have 8 1/4 wave radials. There is a hardware store near here that has a good selection of small diameter aluminum tubing. In fact, I had to replace the very top segment a couple of years ago, because I ruined it trying to remove it when I was overhauling the antenna. That hardware store had the EXACT piece of aluminum I needed. However, I can't remember if they are long enough (4 and 1/2 feet), for a total of 9 feet. Will 8 foot radials do?
Also, when I add ferrite beads to my coax at the base of the antenna, is 73 the right mix? If not, what is the best mix for 27 Mhz?
Thanks! |
Pig040
Intermediate Member
Username: Pig040
Post Number: 331
Registered: 7-2003
| | Posted on Sunday, March 14, 2004 - 10:14 am: |
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Question about your ground wire from the ground rod to the station. I read an article that said that the ground wire should be 9 feet or less. I need at least 15 feet to reach the station. How bad would this be? Thanks |
Tech808
Moderator
Username: Tech808
Post Number: 1807
Registered: 8-2002
| | Posted on Sunday, March 14, 2004 - 10:30 am: |
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Pig040,
Put another Ground Rod in outside window or house as close to your equipment as Possible and use this for Just your Radio Equipment.
If you have to use 15' then you have to as it cannot be helped.
Or if you have a basement Drill a hole thru the Concrete and drive ground rod thru hole to get it closer to your equipment.
Lon
Tech808 |
Tech181
Moderator
Username: Tech181
Post Number: 876
Registered: 7-2001
| | Posted on Sunday, March 14, 2004 - 3:37 pm: |
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Everything you need to know, here...
http://www.polyphaser.com/ppc_pen_home.asp |
Pig040
Intermediate Member
Username: Pig040
Post Number: 333
Registered: 7-2003
| | Posted on Monday, March 15, 2004 - 9:56 am: |
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Thanks 808, and 181, appreciate the informations. |
Tech833
Moderator
Username: Tech833
Post Number: 587
Registered: 8-2002
| | Posted on Tuesday, March 16, 2004 - 2:22 pm: |
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Legend,
I will asnwer as best I can.
"I've read in numerous Amateur publications, that many shorter radials, is preferable to fewer longer (1/4 wave) ones. Also, I notice that there are many (expensive) amateur vertical antennas made with less than 1/4 wave radials. Are these radials really worthless, or only good for "looks"? "
*** Bigbob said it best. Regarding the amateur antennas, when making radials for an 80m antenna, shorter radials are better than none. 80m and 11m (27 MHz.) act much differently. Believe it or not, 80m is even MORE dependent on ground for low takeoff angles. Consider yourself fortunate your interests are in 11m!
"I can't help but wonder what percentage of CB/Ham installations have interconnecting ground rods that are 8 feet apart. I've seen a lot of varying opinions in Amateur publications on this. Anything from triangles with 12 inch spacing, up to six feet. "They cancel each other out"? So it would be every bit as effective to have just ONE rod, as opposed to three, if they are not 8 feet apart? Are you sure? "
*** Clearly, a lot of stations are doing it wrong. If everyone else is marrying same sex partners, does that make it right? Poor example, but same point. I stopped giving talks at ham radio clubs because they stress me out. One guy in his 80's says to use PVC pipe for antennas instead of fiberglass and suddenly he's right and I am wrong. Typical hams. One ham used 20 ground rods all in a circle around his tower base less than 4 feet apart and exclaimed what a great ground he had. Many others followed. I try to tell them why that is no better than a single rod but my voice is squelched by the masses who have done it and do not want to face the fact that their efforts were in vain. Regardless of proof, human will is blind when spread amongst the masses.
"Well, then I guess I've had the same problem for the last 28 years. I have always been able to help my transmitter see a perfect, or near perfect SWR by doing this, assuming that I have the antenna tuned properly. It becomes even more a factor, when patch cords and other appliances are involved in the equation. My equipment gets hot MUCH slower and to a MUCH lesser degree when I present a perfect SWR to the transmitter, even though I know that trimming doesn't affect the ACTUAL SWR at the antenna.
So... no matter how many people argue to the contrary, and insist that trimming is worthless, I have always been of the mindset: "It helps ME a lot, even if it doesn't help someone else. And it sure as heck doesn't hurt anything."
Also, if it is "indicative of a problem", then what kind of problem might that be? Whatever this problem is, I have had it in every CB station configuration I have been involved with. Sometimes, the coax length happened to be right on the money from the start, but when changed... then whamo. Same effect. I know that damn near every one has this "problem", because most people will acknowledge that their SWR *readings* will change with varying lengths of coax. Not the ACTUAL SWR, but the SWR that their transmitter sees, which is STILL important for efficient operation. "
*** It only means that your feedpoint is not precisely tuned at your operating frequency. Let's say your feedpoint is 50 ohms, +j15. Your SWR would be low, but your bandwidth would be narrow due to the highQ. If you played with cable length, you are not changing your feedpoint j, you are instead lowerting the overall Q of your entire system. In other words, the heat that would have heated your radio's small heat sink will now be heating your cable at wavelength multiples instead. No difference in RF power at the feedpoint (other than small cable losses) but an improvement through balance in the reactance at the radio antenna port.
"You never did answer, as far as I can tell. (unless this was it) "
*** Answer was statement about loose connection given later in post. Intermod happens on receive only antennas too.
"So it's not possible that I have any RF coming back down the outer braid from the antenna base? If I did, wouldn't a balun or RF choke help reduce this? "
*** No. You have generated noise coming down your cable perhaps.
"OK... how about for ANY purpose? What purposes might see some benefit, and where would I place the split beads? "
*** Ferrite beads are great for decoupling. If your system has to rely on beads around the coax to decouple the cable from the system, then there is another problem which is not being addressed. It is a bubblegum tire patch answer.
"I'm sorry for my ignorance, but could you be more specific about your meaning? I have never used Penetrox before, or copper bonding. When you say "at sites", are you referring to the union points of the antenna parts? Where can one buy Penetrox, and where do I spray it? On all of the connection points of the antenna? "
*** I do not believe you are ignorant. It is people like you coming to this forum that keeps me interested in it. I appreciate you taking the time to request help. Penetrox is a thick 'Elmer's glue' consistence material which is filled with metal. It is used for bonding metallic things at communications sites. 'Sites' refers to communications sites. Penetrox is available at ham radio stores and some hardware stores.
"Again, I apologize for my ignorance. I very much appreciate your efforts to answer my questions. "
*** It is truly my pleasure.
ANSWER FOR 'Dindin'-
"Tech833,
I read and reread your postings on the Serio antenna and something just dont sound right;"All the ground radials less than 8 feet long serve no purpose other than for looks."
after reading that I would like to see a spectrum analyzer test on this antenna and the effect the different sized ground radials would have(on harmonics).In todays market a manufacturer,in order to survive is not going to let fluff over functionality cut at profits.Those small radials may not cost the manufacturer much,but they do cost him something(profit).as far as looks go,I dont care for the way it looks.Nor am i trying to endorse it for I have not used one.I'm more of a Maco fan.Although my favorites were the Hustler 27JR and Super Swamper,would love to get a hold of either one of those! I do agree on the use of the Penetrox and bonding of all the parts.It may be a regional thing but NoAlox is easier to find around here than Penetrox.sorry about getting long winded but felt I had to add my t.c.w."
*** What would a spectrum analyzer do to show the effect of short radials under an antenna? A spectrum analyzer is used to examine losses, radiation, signals, etc. across a specified RF spectrum. Harmonics would be potentially increased by adding short radials, but you would measure that on a test range or in emulation software to save the trip in the field. Your second point is an assumption. LOOKS sells antennas as much or more than performance. Sad but true.
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Legend
Junior Member
Username: Legend
Post Number: 21
Registered: 12-2002
| | Posted on Wednesday, March 17, 2004 - 10:30 am: |
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OK... I have three more questions.
1) Even if it doesn't do any good, will it have any harmful effects to add 4 or 5 spilt beads to my RG-8, just below the antenna feedpoint?
2) If I do add beads, what mix is best for 27 Mhz? 43? 73? Other?
3) I have noticed that some people recommend putting an RF choke (a small coil of 6 or 8 turns of coax) just below the antenna feedpoint. Which is better? Beads? or coaxial choke?
4) OK, I lied. I have 4 questions... lol.
What does a "Common Mode Filter" do? What about a "Line Isolator"? How about a "Current Balun"?
Thanks! |
Tech833
Moderator
Username: Tech833
Post Number: 596
Registered: 8-2002
| | Posted on Friday, March 19, 2004 - 1:48 am: |
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OK... I have three more questions.
*** I will try my best.
1) Even if it doesn't do any good, will it have any harmful effects to add 4 or 5 spilt beads to my RG-8, just below the antenna feedpoint?
*** It will not harm anything.
2) If I do add beads, what mix is best for 27 Mhz? 43? 73? Other?
*** 43 material is best for VHF. The 73 material may work better. Go to Amidon's website and look at the chart. It shows attenuation by frequency and material thickness. Informative!
3) I have noticed that some people recommend putting an RF choke (a small coil of 6 or 8 turns of coax) just below the antenna feedpoint. Which is better? Beads? or coaxial choke?
*** It depends on the purpose. If it is decoupling, then beads work better. If it is for lightning suppression, then the coil works better.
4) OK, I lied. I have 4 questions... lol.
What does a "Common Mode Filter" do? What about a "Line Isolator"? How about a "Current Balun"?
*** That is 3 separate questions. No fair. A common Mode Filter (CMF) is used in cases of interference derived from phase lag between differential signals (time lag between signals). A Line Isolator is used either in the A/C line or audio line or sometimes phone lines connected to equipment. It is to float the neutral. You would use that if you are getting hum interference. A current balun is another way of saying impedance transformer. It is sometimes used to suppress common mode current.
Thanks!
*** You're welcome. |
Charliebrown
Junior Member
Username: Charliebrown
Post Number: 29
Registered: 10-2002
| | Posted on Friday, March 19, 2004 - 1:03 pm: |
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tech 808, i just received the max 2000 and so far it performs just as i have been told. it increased my receive and trans. on average of 1 to 2 db. 3 out of 4 people said they noticed the increase on my signal. for some reason only 1 said no improvement. i like the max better than i thought. you have always given me good information and i for one thank you so much for taking the time to help me and others. |
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