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Base Antenna HELP to much RF
- Thread starter KENWOOD570
- Start date
you've got to run a low pass filter after that amp.
buy a good one like a bencher, a drake, or a nye viking.
dont even bother with a para dynamics or any other cheapie.
the good ones cost more than 50.00 new.
check ebay, good deals there.
now, if you have your antenna grounded, but not your equipment, and the antenna ground is not tied in with the house AC system, then your grounding may be causing more problems than it is curing.
if your mast has a good metal to metal connection all the way down then you can just connect the ground rod(s) to the bottom of the mast. if not, you will need to run an 8ga. min. solid cop per wire down to the ground rods from the antenna mounting bracket.
then pound in a ground rod right outside the shack, and connect all your equipment through a ground bus, to this ground rod.
connect this ground rod to the antenna ground rod with more 8ga. solid copper wire.
doesnt matter how long this wire is, just needs to connect the two grounding points.
then, run a wire from either ground rod to the ground wire of the house AC system at the box.
now you have a single point ground.
run quality coax that is double shielded like LMR400 or 9913 to the antenna.
doing all this and using the low pass filter is the best you can do on your end.
i would say replace your modulation limiter, but you are running a kenwood. that is good.
if none of this helps, or you dont want to bother with it all, (you should, your station will work better and be safer)
then buy some snap on ferrite beads and put them on your neighbors tv power cord, cables, and the computer speaker wires and power cables.
best of luck to you,
you are going to have a hard time trying to clean up that X-force.
loosecannon
buy a good one like a bencher, a drake, or a nye viking.
dont even bother with a para dynamics or any other cheapie.
the good ones cost more than 50.00 new.
check ebay, good deals there.
now, if you have your antenna grounded, but not your equipment, and the antenna ground is not tied in with the house AC system, then your grounding may be causing more problems than it is curing.
if your mast has a good metal to metal connection all the way down then you can just connect the ground rod(s) to the bottom of the mast. if not, you will need to run an 8ga. min. solid cop per wire down to the ground rods from the antenna mounting bracket.
then pound in a ground rod right outside the shack, and connect all your equipment through a ground bus, to this ground rod.
connect this ground rod to the antenna ground rod with more 8ga. solid copper wire.
doesnt matter how long this wire is, just needs to connect the two grounding points.
then, run a wire from either ground rod to the ground wire of the house AC system at the box.
now you have a single point ground.
run quality coax that is double shielded like LMR400 or 9913 to the antenna.
doing all this and using the low pass filter is the best you can do on your end.
i would say replace your modulation limiter, but you are running a kenwood. that is good.
if none of this helps, or you dont want to bother with it all, (you should, your station will work better and be safer)
then buy some snap on ferrite beads and put them on your neighbors tv power cord, cables, and the computer speaker wires and power cables.
best of luck to you,
you are going to have a hard time trying to clean up that X-force.
loosecannon
lords
Active Member
run quality coax that is double shielded like LMR400 or 9913 to the antenna.
yea, I been looking at 100 or so foot of that LMR400DB
its looking better everyday
yea, I been looking at 100 or so foot of that LMR400DB
its looking better everyday
You know, it really is amazing. People spend who knows how much on something that they think is going to 'cure' a problem' when it isn't even associated with the real problem. The bad part of the whole thing is that a single attribute is construed to be the 'fix' for something entirely in another place. Who ever said 'snake oil' isn't still popular!
- 'Doc
- 'Doc
lords
Active Member
ya the main problem is that dam Imax ..you can only cure so much of that splatter out of it ..just like a a99 Splatters....
I don't care what you do to them you ain't going to cure the problem over 60%
I don't care what you do to them you ain't going to cure the problem over 60%
Well this weekend I am going to fix the grounds correctly and the the Coax. Where can I find the Coax?
Thanks
Jerry
Thanks
Jerry
I hope you don't tie all the house grounds together like mentioned above.KENWOOD570 said:
Remember, keep ALL RF grounds as short as possible!!!! Ground your radio gear to a ground rod just outside of your radio room. Ground your tower/mast to a ground rod at the base of your structure. DON'T TIE THEM TOGETHER. You can add a ground rod at the base of your service entrance. Don't tie this to your RF grounds.
The best example of grounding a building is probably a repeater enclosure on top of a mountain. They run a WIDE copper plate (ring) all around the interior of the building. Then every 4' they run a ground wire through the wall of the building to a ground rod just outside. Those rods are also tied together, but at every 4 feet! Running a 6ga wire all the way around the house is asking for trouble unless you add ground rods as you go.
I am no expert on grounding but have seen how its done right. There is a lot of professional information available out here on the net. Tieing all your grounds together doesn't sit well with me.
I'd start by reading what Polyphaser has to say:
http://www.polyphaser.com/technical_notes.aspx
current flowing into the antenna end must be equalled by current flowing into a ground or counterpoise of some type.
what this means is that if we have any type of end-fed antenna without a radial or counterpoise system, the outside of the coax shield, supporting mast or anything attached to the feedline must carry an equal amount of current to that flowing into the antenna.
the antennas mentioned previously are built and packaged without any type of ground plane or counterpoise so half of the antenna is literally missing. since displacement currents cannot be distributed to a non-existent counterpoise, the only conductors having a connection to the antenna are the feedline shield and the supporting mast, that's where the return current ends up.
that's the way the manufacturers planned it. then they had the temerity to offer to sell you the other half of your antenna as an option knowing full well that most of them would end up connected to a coaxial feedline (outer shield common mode current return) and mounted on some conductive support structure but the requirements were met for a two terminal power transfer of energy from a generator to a load. with half of the antenna missing the return currents from the second terminal are routed down the outside of the shield and up and down the mast. this is a perfect example of poor antenna design. in cases such as this you damn well better have some type of an rf ground but the truth is that if an antenna is fed properly there is absolutely no need for a station rf ground! the station rf ground is a band-aid for poor antenna system design. in the case of any end fed antenna that's all it is. in the case of any end fed antenna (including a 1/2 wave) ALL of the antenna current flows over the feedline shield. THIS IS NOT GOOD. many antenna designs actually use the feedline and mast radiation that others dismiss as "insignificant" to increase antenna gain. in some cases, the antenna designers really don't even understand that this is exactly what they're doing!
with respect to the original questions asked here, the amplifier and the extreme likelyhood that it is being driven excessively is only exacerbating this entire situation. you're not looking for "a fix" but indeed several of them. the first place to start is the antenna.
ANY END-FED ANTENNA REQUIRES A LARGE GROUNDPLANE OR OTHER EXTRAORDINARY ISOLATION METHOD OR METHODS TO PREVENT FEEDLINE OR MAST COMMON MODE CURRENTS!
if they're on the outer shield and the mast (all the way up and down) at 1000W they're still there at 100W. the much poorer IMD levels associated with the xforce amplifier as compared to the hf rig aren't helping the situation any either. you would also do well to completely disregard any recommendations from xforce as to the amount of drive recommended and determine this for yourself by locating the drive specifications of the manufacturer of the devices used in the amplifier to determine proper drive levels required from your hf rig and apply them. that alone could eliminate a noticable amount of the interference symptoms.
what this means is that if we have any type of end-fed antenna without a radial or counterpoise system, the outside of the coax shield, supporting mast or anything attached to the feedline must carry an equal amount of current to that flowing into the antenna.
the antennas mentioned previously are built and packaged without any type of ground plane or counterpoise so half of the antenna is literally missing. since displacement currents cannot be distributed to a non-existent counterpoise, the only conductors having a connection to the antenna are the feedline shield and the supporting mast, that's where the return current ends up.
that's the way the manufacturers planned it. then they had the temerity to offer to sell you the other half of your antenna as an option knowing full well that most of them would end up connected to a coaxial feedline (outer shield common mode current return) and mounted on some conductive support structure but the requirements were met for a two terminal power transfer of energy from a generator to a load. with half of the antenna missing the return currents from the second terminal are routed down the outside of the shield and up and down the mast. this is a perfect example of poor antenna design. in cases such as this you damn well better have some type of an rf ground but the truth is that if an antenna is fed properly there is absolutely no need for a station rf ground! the station rf ground is a band-aid for poor antenna system design. in the case of any end fed antenna that's all it is. in the case of any end fed antenna (including a 1/2 wave) ALL of the antenna current flows over the feedline shield. THIS IS NOT GOOD. many antenna designs actually use the feedline and mast radiation that others dismiss as "insignificant" to increase antenna gain. in some cases, the antenna designers really don't even understand that this is exactly what they're doing!
with respect to the original questions asked here, the amplifier and the extreme likelyhood that it is being driven excessively is only exacerbating this entire situation. you're not looking for "a fix" but indeed several of them. the first place to start is the antenna.
ANY END-FED ANTENNA REQUIRES A LARGE GROUNDPLANE OR OTHER EXTRAORDINARY ISOLATION METHOD OR METHODS TO PREVENT FEEDLINE OR MAST COMMON MODE CURRENTS!
if they're on the outer shield and the mast (all the way up and down) at 1000W they're still there at 100W. the much poorer IMD levels associated with the xforce amplifier as compared to the hf rig aren't helping the situation any either. you would also do well to completely disregard any recommendations from xforce as to the amount of drive recommended and determine this for yourself by locating the drive specifications of the manufacturer of the devices used in the amplifier to determine proper drive levels required from your hf rig and apply them. that alone could eliminate a noticable amount of the interference symptoms.
Wow this is deeper then I thought! so in laymens terms, 1) I am going to disconect my ground wire form my Imax and attach it to the base of my mast. The other end two feet away soldered to my 8' gorunding stake. 2) Attach my Radio and amp to my grounding rod just outside my room. 3) Replace my coax with LM400. 4) Order an antenna with radials ie I-10K or Maco V5/8 if I can not get a I-10k. Does this sound like a plan?
Thanks
Jerry
Thanks
Jerry
yes. plan on picking up a well built 1:1 current balun to go with it.
install both of them properly and eliminate all external rf ground connections.
install both of them properly and eliminate all external rf ground connections.
The way to fix any problem is to fix it where the problem exists, not where is doesn't exist, or is easy to mess with.
The original 'problem' concerns the neighbor's RFI. There are two very basic steps to that kind of problem; make sure -you- aren't causing it by radiating things you shouldn't be radiating, and stopping the TV and speakers from receiving signals they shouldn't be receiving. There are two 'sides' to the problem, your's and then his. Each 'side' should solve their own problems. Sticking your nose in to solving 'his' problem is sort of asking for it. Same for his solving 'your' problems. Depends a lot on how well you get along with your neighbor, you know?
Your neighbor is at a disadvantage because computer sound systems are notoriously prone to interference. So are TVs not made within the last couple'a few years. Just a fact of life, and sometimes almost impossible to 'cure'. There are things each of you can, and should do.
The first thing is that both of you should contact the FCC and ask for the "Interference Handbook", it's free. Read the dang thing, it'll outline the responsibilities of both parties and give suggestions on how to 'fix' things. (that'll go over like a lead balloon!)
I think you'll find that you are at a disadvantage also, -if- you are operating on 11 meters. If you are, then you're going to have to be pretty 'sly' in how you 'fix' things. You are also going to be more 'accountable'/'liable' than your neighbor. (Sorry, but that's how it is. In that case, it pays to be a little more 'helpful' to your neighbor than is absolutely necessary.)
So far everything discussed has been about your end of the thing. That's all well and good (except for some of the advice). But considering what's being interfered with, it really isn't going to solve much.
The best 'fix' is almost never the easiest or the fastest thing to do. It certainly won't be much, but I'd be willing to bet that your 'fixes' this weekend(?) are not going to solve the matter. There are no "magic" fixes.
Good luck!
- 'Doc
The original 'problem' concerns the neighbor's RFI. There are two very basic steps to that kind of problem; make sure -you- aren't causing it by radiating things you shouldn't be radiating, and stopping the TV and speakers from receiving signals they shouldn't be receiving. There are two 'sides' to the problem, your's and then his. Each 'side' should solve their own problems. Sticking your nose in to solving 'his' problem is sort of asking for it. Same for his solving 'your' problems. Depends a lot on how well you get along with your neighbor, you know?
Your neighbor is at a disadvantage because computer sound systems are notoriously prone to interference. So are TVs not made within the last couple'a few years. Just a fact of life, and sometimes almost impossible to 'cure'. There are things each of you can, and should do.
The first thing is that both of you should contact the FCC and ask for the "Interference Handbook", it's free. Read the dang thing, it'll outline the responsibilities of both parties and give suggestions on how to 'fix' things. (that'll go over like a lead balloon!
)I think you'll find that you are at a disadvantage also, -if- you are operating on 11 meters. If you are, then you're going to have to be pretty 'sly' in how you 'fix' things. You are also going to be more 'accountable'/'liable' than your neighbor. (Sorry, but that's how it is. In that case, it pays to be a little more 'helpful' to your neighbor than is absolutely necessary.)
So far everything discussed has been about your end of the thing. That's all well and good (except for some of the advice). But considering what's being interfered with, it really isn't going to solve much.
The best 'fix' is almost never the easiest or the fastest thing to do. It certainly won't be much, but I'd be willing to bet that your 'fixes' this weekend(?) are not going to solve the matter. There are no "magic" fixes.
Good luck!
- 'Doc
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