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#1
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hi
I've been using a dipole antenna about 30ft each side connected to a sgc tuner with about 5ft of ladderline . this is mounted on my roof's elevator shack. recently the elevator gear was upgrated to modern stuff and i've suffered with s9 steady but intermittant (sounds like noise level /background noise) 3min on 3min off like noise from 1-30mhz ever since it's mostly strongest from 1-7mhz and heavest on 80m SO my building wo'nt let me get to crazy antenna wise but my question is is there a type of antenna i could put up such that it would be very def below the antenna or something i could do that would accomplish this effect? and mitigate the interference perhaps?? would say a regular 3 element beam reduce the noise or just perhaps 'amplify' it how about a verticle w/ few radials? or something i am overlooking my last choice and what i'd guess building wouldn't approve would be to put 2 receive only stearing verticles away from the elevator room not sure if that'd work technically but the other parts of the roof are off limits to me so i'd be a VERY hard sell but i wonder if that'd help or just ultimately be too noisy as verticles sometimes are i don't have any other mounting locations nor any luck w/the elevator company just looking for some suggestings thanks all happy holidays |
#2
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![]() Well, that is a tough situation... On the antenna my first thought is a two element horizontal quad beam pointed straight up.... The reflector will tend to shield the driven from noise emanating from below... BUT, the noise being in the near field all bets are off and you will just have to try... You might also try a phasing noise reducer, like the MFJ 1025, etc... Again, the noise being all around you may be impossible to reduce, but then maybe not... Only a trial will tell... You didn't mention the rig... Perhaps some DSP will help with reducing noise... Also going to narrow modes like CW gasp, who does that ancient mode? and PSK with narrow CRYSTAL filters will help... In the end, you will likely have to team up with kindred souls and establsih a remote radio station operated the internet as your solution... denny / k8do |
#3
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In article ,
"Jimmie D" wrote: "ml" wrote in message ... hi I've been using a dipole antenna about 30ft each side connected to a sgc tuner with about 5ft of ladderline . this is mounted on my roof's elevator shack. recently the elevator gear was upgrated to modern stuff and i've suffered with s9 steady but intermittant (sounds like noise level /background noise) 3min on 3min off like noise from 1-30mhz ever since it's mostly strongest from 1-7mhz and heavest on 80m SO my building wo'nt let me get to crazy antenna wise but my question is is there a type of antenna i could put up such that it would be very def below the antenna or something i could do that would accomplish this effect? and mitigate the interference perhaps?? would say a regular 3 element beam reduce the noise or just perhaps 'amplify' it how about a verticle w/ few radials? or something i am overlooking my last choice and what i'd guess building wouldn't approve would be to put 2 receive only stearing verticles away from the elevator room not sure if that'd work technically but the other parts of the roof are off limits to me so i'd be a VERY hard sell but i wonder if that'd help or just ultimately be too noisy as verticles sometimes are i don't have any other mounting locations nor any luck w/the elevator company just looking for some suggestings thanks all happy holidays Sounds like the elevator went from mechanical switching telectronic switching Jimmie Hi thanks to all thAt responded ,yes the old elevator has nothing but a open frame rack of open style relays and a motor i think from late 50's early 60's nevery gave me a problem the new stuff i ckt boards inside of metal boxes all computerized etc w/new motors |
#4
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In article
, Denny wrote: Well, that is a tough situation... On the antenna my first thought is a two element horizontal quad beam pointed straight up.... The reflector will tend to shield the driven from noise emanating from below... BUT, the noise being in the near field all bets are off and you will just have to try... You might also try a phasing noise reducer, like the MFJ 1025, etc... Again, the noise being all around you may be impossible to reduce, but then maybe not... Only a trial will tell... You didn't mention the rig... Perhaps some DSP will help with reducing noise... Also going to narrow modes like CW gasp, who does that ancient mode? and PSK with narrow CRYSTAL filters will help... In the end, you will likely have to team up with kindred souls and establsih a remote radio station operated the internet as your solution... denny / k8do thanks for the responce, unf i wouldn't be able to put up a quad love to thou I actually have a anc4 which practically never seemed to work for anything in this case i wonder if it might currently my ant and anc4 antenna are together i wonder if i put the anc4 antenna either further away or perhaps inside the elevator room right near the equipment (forgot which) that might do it, also my antenna for that right now is just some old cat 5 i ran to the roof the idea of a remote might not be to bad since i only need it as a receiver |
#5
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On Thu, 27 Dec 2007 11:53:49 GMT, ml wrote:
I've been using a dipole antenna about 30ft each side connected to a sgc tuner with about 5ft of ladderline . this is mounted on my roof's elevator shack. Hi Myles, You first need to differentiate between radiated noise and conducted noise - you obviously know where the source is. To conducted noise: Does the SGC share the same ground as the switching loads for the elevator? If so, you want to find another ground. ANOTHER ground? A jillion floors above earth? What does ground mean in that context? The path for the motors' heavy current is through a wire. That wire has resistance (however small). The current through that resistance elevates "ground" above the normally placid and noiseless ground with a hash of voltage noise that goes right into anything SHARING that path (and also having alternative paths to the same ground - it is quite common). Finding another ground can be approached through two ways: randomly, or analytically. Analytically can be masked by failures due to what is perceived to be ground (that is how this all began). Randomly dooms you to useless repetition in the guise of a new choice being a different choice (often quite rare). Random has the benefit of being quick and luck may come your way suddenly (it can also vanish just as fast when something changes - this how all this began). Analytically: Where do you ground things on top of the elevator shed? Move that to wire it to a more remote point. If you don't ground anywhere on the roof, then we move on: To consider radiated noise: This is the same noise being coupled through the air. If you don't ground at the roof, then you might have long conductors that run in close proximity to the heavy current burdened wires of the motors. If so, then you will want to choke your wires going down to your shack. ALL OF THE WIRES GOING TO YOUR SHACK. You may need to do this repeatedly along their length. You are going to get an education in Ferrites if this proves to be the solution. As an aside: the new stuff i ckt boards inside of metal boxes If you can, closely examine those boxes to see if they have a separate ground wire. Follow it where ever it might go. This might identify a quiet ground, or a noisy ground point for you to try to tie into as part of your experimentation. Similarly, If you can, closely examine those motors to see if they have a separate ground wire. See if they go anywhere you can use, or avoid as the conditions of experimentation reveals. 73's Richard Clark, KB7QHC |
#6
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In article ,
Richard Clark wrote: On Thu, 27 Dec 2007 11:53:49 GMT, ml wrote: I've been using a dipole antenna about 30ft each side connected to a sgc tuner with about 5ft of ladderline . this is mounted on my roof's elevator shack. Hi Myles, You first need to differentiate between radiated noise and conducted noise - you obviously know where the source is. To conducted noise: Does the SGC share the same ground as the switching loads for the elevator? If so, you want to find another ground. ANOTHER ground? A jillion floors above earth? What does ground mean in that context? The path for the motors' heavy current is through a wire. That wire has resistance (however small). The current through that resistance elevates "ground" above the normally placid and noiseless ground with a hash of voltage noise that goes right into anything SHARING that path (and also having alternative paths to the same ground - it is quite common). Finding another ground can be approached through two ways: randomly, or analytically. Analytically can be masked by failures due to what is perceived to be ground (that is how this all began). Randomly dooms you to useless repetition in the guise of a new choice being a different choice (often quite rare). Random has the benefit of being quick and luck may come your way suddenly (it can also vanish just as fast when something changes - this how all this began). Analytically: Where do you ground things on top of the elevator shed? Move that to wire it to a more remote point. If you don't ground anywhere on the roof, then we move on: To consider radiated noise: This is the same noise being coupled through the air. If you don't ground at the roof, then you might have long conductors that run in close proximity to the heavy current burdened wires of the motors. If so, then you will want to choke your wires going down to your shack. ALL OF THE WIRES GOING TO YOUR SHACK. You may need to do this repeatedly along their length. You are going to get an education in Ferrites if this proves to be the solution. As an aside: the new stuff i ckt boards inside of metal boxes If you can, closely examine those boxes to see if they have a separate ground wire. Follow it where ever it might go. This might identify a quiet ground, or a noisy ground point for you to try to tie into as part of your experimentation. Similarly, If you can, closely examine those motors to see if they have a separate ground wire. See if they go anywhere you can use, or avoid as the conditions of experimentation reveals. 73's Richard Clark, KB7QHC Dear Rich Thanks very much!! Gave me a lot of things to study n try Happy new years I didn't have any roof ground options did in my apt, my first experiment was to put the antenna on a test rig(817) by itself on battery same exact problem disconnecting the ant at roof kills the noise so i presume most if it is picked up via antenna not sure if this was scientific seems true thou Getting inside that room thou or once inside the cabnets might prove difficult the building considers the new work up there as sacrade grounds now they didn't even paint the room, and can't figure this one out, took out the 120v outlet that used to be on the wall for service not even sure thats legal (code) but certainly inconvient so what i saw from looking in the window didn't tell me anything about grounds but an execellent idea i overlooked, i can see their cabinets are connected via metal conduit so i presume there is some ground made couldn't tell of the motors the wires are in a conduit that seems to go tothe motor so i can't see any actual connections i was always guessing it wasn't the motor since the noise will occur even if the motor isn't turning however i understand now that it could be either an antenna or energized during it's still moments the motors are closest to my antena and the cabinets are furthest and at right angles perp however the entire room is only 15x15 i just can't figure why the noise isn't constant thou or exactly intermittant ie it can be on 3 off 2 on 4 off 7 thanks very much Rich!! |
#7
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On Mon, 31 Dec 2007 10:36:14 GMT, ml wrote:
Dear Rich Thanks very much!! Gave me a lot of things to study n try Happy new years I didn't have any roof ground options did in my apt, my first experiment was to put the antenna on a test rig(817) by itself on battery same exact problem Hi Myles, Good. I would still implore you to consider that ground can arrive on the rig through numerous side paths. You say it was on battery power, but is that battery served with a floating charger? Possible path to ground there. Do you use an external keyer with an external power supply (wall wart)? Possible path to ground there. Is your rig connected to your computer for any reason? Possible path to ground there. And so on.... disconnecting the ant at roof kills the noise so i presume most if it is picked up via antenna not sure if this was scientific seems true thou No problem with "scientific method" here, none at all. Unlike the armchair theorists busily pounding conventional thinking into the dust of other threads, you pursuits are vastly more informing. Now, when you say you disconnect that antenna, that means only the two wires of the dipole and no other connection? If so, replace those two wires with a dummy load to judge how well the path for transmission remains (do a SWR test). Replace the wires of the dipole with a small (18 inch diameter) recieve loop. How does that perform, noise-wise? Try using a small portable radio in the vicinity of the elevator shed and do a noise survey, making a map to see if you can find a hot spot. Getting inside that room thou or once inside the cabnets might prove difficult the building considers the new work up there as sacrade grounds now they didn't even paint the room, and can't figure this one out, took out the 120v outlet that used to be on the wall for service not even sure thats legal (code) but certainly inconvient so what i saw from looking in the window didn't tell me anything about grounds but an execellent idea i overlooked, i can see their cabinets are connected via metal conduit so i presume there is some ground made couldn't tell of the motors the wires are in a conduit that seems to go tothe motor so i can't see any actual connections Take a look inside each time you visit. Perhaps in time it will become more familiar and the solution will leap out at you. i was always guessing it wasn't the motor since the noise will occur even if the motor isn't turning however i understand now that it could be either an antenna or energized during it's still moments Good observations. Think about this in the context of my suggestion above about the portable radio. the motors are closest to my antena and the cabinets are furthest and at right angles perp however the entire room is only 15x15 i just can't figure why the noise isn't constant thou or exactly intermittant ie it can be on 3 off 2 on 4 off 7 This may take more time with you on the roof during high traffic periods. In the shack, you might want to make a detail log of time of occurence to see if it correlates to some particular activity. Obviously this implies the typical morning, lunch, and evening traffic of the building, but analysis might show a constant noise field. thanks very much Rich!! 73's Richard Clark, KB7QHC |
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