| Page 2 of 2 | 1 | 2 |
|
|
Five Basic Steps to Better Shortwave Radio Listening [SWL]
On Jan 18, 4:23*pm, dave wrote:
On 01/18/2011 02:17 PM, D. Peter Maus wrote: On 1/18/11 16:05 , bpnjensen wrote: On Jan 18, 10:57 am, John wrote: On 1/18/2011 10:44 AM, bpnjensen wrote: ... Actually, no, and I am sorry if there was a misunderstanding - I meant an inline (in the coax) RFI reduction system. Baluns/ununs really are NOT an RFI reduction system. They provide proper impedance matching between antenna and feedline. Coax, with an rf choke (can be a balun/unun) allows the feedline to run though noisy areas and not pick up the noise there, such as when it enters a house with noise present. Baluns/ununs/rf-transformers, because of the use in gaining a superior match (transfer of signal energy) improves signal to noise ratio, in most instances, and this can appear to be functioning as a "RFI reduction system." Some useful links:http://users.belgacom.net/hamradio/s...ongwire%20Balu... Regards, JS OK, understood, but I have always thought (based on what I have read) that one of these matching transformers, properly deisgned and grounded, can bleed off some noise to ground. Am I misled? Local environmental noise, and static, yes. Man made noise, or noise radiated into the antenna space, not so much, no. A properly designed matching transformer will improve the transfer of antenna output to the receiver. And it will help drain off static buildup on the antenna, and help reduce the noise floor. But, if noise is being radiated into the air, as from powerlines, digital toys, and dimmers and similar sources, and your antenna is picking that up, it will depend on the antenna's ability to discriminate between desired and undesired frequencies whether or not you see a reduction in undesired signals. It sounds as though much of your noise problem is related to your connection to the mains. Mains borne noise is a big problem in radio hobbycraft. Most of the noise in my own area is brought in through the mains. The remainder is radiated from the hundreds of devices throughout the neighborhood. It's possible, though a PITA to do so, to bypass the mains with safety caps between .1 - .01mfd (safety caps are essential, here, for fire prevention) to reduce the irregular impulses on the line. And isolation transformer, balanced to ground will also produce significant results in reducing your noise, but that can be expensive. Your least difficult path may be in isolating your radios from the mains, entirely, and move to battery power. You need to embrace ferrites. They're like putting a low pass filter is series with your mains. Shunt caps are scary. MOVs, sure. Thanks - Maybe, but I think ferrites on the RF cables might be more critical than on the power cables. The radios are nice and quite when I disconnect the antennae; no noise level at all even with the multiple preamps all the way up. |
Five Basic Steps to Better Shortwave Radio Listening [SWL]
On 1/18/11 21:59 , bpnjensen wrote:
On Jan 18, 2:17 pm, "D. Peter wrote: On 1/18/11 16:05 , bpnjensen wrote: On Jan 18, 10:57 am, John wrote: On 1/18/2011 10:44 AM, bpnjensen wrote: ... Actually, no, and I am sorry if there was a misunderstanding - I meant an inline (in the coax) RFI reduction system. Baluns/ununs really are NOT an RFI reduction system. They provide proper impedance matching between antenna and feedline. Coax, with an rf choke (can be a balun/unun) allows the feedline to run though noisy areas and not pick up the noise there, such as when it enters a house with noise present. Baluns/ununs/rf-transformers, because of the use in gaining a superior match (transfer of signal energy) improves signal to noise ratio, in most instances, and this can appear to be functioning as a "RFI reduction system." Some useful links:http://users.belgacom.net/hamradio/s...ongwire%20Balu... Regards, JS OK, understood, but I have always thought (based on what I have read) that one of these matching transformers, properly deisgned and grounded, can bleed off some noise to ground. Am I misled? Local environmental noise, and static, yes. Man made noise, or noise radiated into the antenna space, not so much, no. A properly designed matching transformer will improve the transfer of antenna output to the receiver. And it will help drain off static buildup on the antenna, and help reduce the noise floor. But, if noise is being radiated into the air, as from powerlines, digital toys, and dimmers and similar sources, and your antenna is picking that up, it will depend on the antenna's ability to discriminate between desired and undesired frequencies whether or not you see a reduction in undesired signals. It sounds as though much of your noise problem is related to your connection to the mains. Mains borne noise is a big problem in radio hobbycraft. Most of the noise in my own area is brought in through the mains. The remainder is radiated from the hundreds of devices throughout the neighborhood. It's possible, though a PITA to do so, to bypass the mains with safety caps between .1 - .01mfd (safety caps are essential, here, for fire prevention) to reduce the irregular impulses on the line. And isolation transformer, balanced to ground will also produce significant results in reducing your noise, but that can be expensive. Your least difficult path may be in isolating your radios from the mains, entirely, and move to battery power. Thanks, Peter - This may be all true - but for the record, with the radios plugged in, I disconnected the antennas and kept the grounds connected. The radios got very quiet; based on this, I don't think it's the mains. I had a noise I couldn't get rid of, a few years ago. Everything pointed to some radiated phenomenon. Tried disconnecting the antenna. Things got very quiet. Finally tracked it down with a Zenith transistor radio. It was, in fact, noise on the mains, radiated into the antenna space. Filtered the line and modded an offending device that was putting the spike on the line. Cleaned it right up. A transitor radio can be useful in tracking down the source. Follow the noise, turn off each implement one at a time, and you'll find the source or sources of noise. You sound like you're living in the noise equivalent of the Little Big Horn. FWIW, I have an RFI filter on the 115 VAC - this item: ICE: http://www.iceradioproducts.com/imag...ersarticle.pdf The difference between using it and not using it is slight, but noticeable. Such a device is best used as close to the source as practical. |
Five Basic Steps to Better Shortwave Radio Listening [SWL]
On 1/18/2011 10:10 PM, Bob Dobbs wrote:
... GAWD! And, I thought I had it bad ... Regards, JS |
Five Basic Steps to Better Shortwave Radio Listening [SWL]
On Jan 18, 8:21*pm, "D. Peter Maus" wrote:
On 1/18/11 21:59 , bpnjensen wrote: On Jan 18, 2:17 pm, "D. Peter *wrote: On 1/18/11 16:05 , bpnjensen wrote: On Jan 18, 10:57 am, John * *wrote: On 1/18/2011 10:44 AM, bpnjensen wrote: ... Actually, no, and I am sorry if there was a misunderstanding - I meant an inline (in the coax) RFI reduction system. Baluns/ununs really are NOT an RFI reduction system. *They provide proper impedance matching between antenna and feedline. *Coax, with an rf choke (can be a balun/unun) allows the feedline to run though noisy areas and not pick up the noise there, such as when it enters a house with noise present. Baluns/ununs/rf-transformers, because of the use in gaining a superior match (transfer of signal energy) improves signal to noise ratio, in most instances, and this can appear to be functioning as a "RFI reduction system." Some useful links:http://users.belgacom.net/hamradio/s...ongwire%20Balu... Regards, JS OK, understood, but I have always thought (based on what I have read) that one of these matching transformers, properly deisgned and grounded, can bleed off some noise to ground. *Am I misled? * * Local environmental noise, and static, yes. Man made noise, or noise radiated into the antenna space, not so much, no. * * A properly designed matching transformer will improve the transfer of antenna output to the receiver. And it will help drain off static buildup on the antenna, and help reduce the noise floor. But, if noise is being radiated into the air, as from powerlines, digital toys, and dimmers and similar sources, and your antenna is picking that up, it will depend on the antenna's ability to discriminate between desired and undesired frequencies whether or not you see a reduction in undesired signals. * * It sounds as though much of your noise problem is related to your connection to the mains. Mains borne noise is a big problem in radio hobbycraft. Most of the noise in my own area is brought in through the mains. The remainder is radiated from the hundreds of devices throughout the neighborhood. * * It's possible, though a PITA to do so, to bypass the mains with safety caps between .1 - .01mfd (safety caps are essential, here, for fire prevention) to reduce the irregular impulses on the line. And isolation transformer, balanced to ground will also produce significant results in reducing your noise, but that can be expensive. * * Your least difficult path may be in isolating your radios from the mains, entirely, and move to battery power. Thanks, Peter - This may be all true - but for the record, with the radios plugged in, I disconnected the antennas and kept the grounds connected. *The radios got very quiet; based on this, I don't think it's the mains. * *I had a noise I couldn't get rid of, a few years ago. Everything pointed to some radiated phenomenon. Tried disconnecting the antenna. Things got very quiet. Finally tracked it down with a Zenith transistor radio. It was, in fact, noise on the mains, radiated into the antenna space. Filtered the line and modded an offending device that was putting the spike on the line. Cleaned it right up. * *A transitor radio can be useful in tracking down the source. Follow the noise, turn off each implement one at a time, and you'll find the source or sources of noise. * *You sound like you're living in the noise equivalent of the Little Big Horn. FWIW, I have an RFI filter on the 115 VAC - this item: ICE: http://www.iceradioproducts.com/imag...ersarticle.pdf The difference between using it and not using it is slight, but noticeable. * *Such a device is best used as close to the source as practical. This one is plugged into the wall between the radio and the socket. Can you get any closer than that? I also know factually that a MW radio brought near things like wall switches and plugs results in a 60 Hz hum on the radio. It is really noticeable with a little loop antenna swiveled around - whenever it points to the wall switch, you hear that hum. The hum is not apparent on the SW bands at all; but on powerhouse MW stations like KGO locally here, the hum is solidly behind the audio. |
Five Basic Steps to Better Shortwave Radio Listening [SWL]
On Jan 18, 10:10*pm, Bob Dobbs wrote:
D. Peter Maus wrote: * You sound like you're living in the noise equivalent of the Little Big Horn. Before the last move three years ago I lived close to there. Or so it seemedhttp://img.myph.us/Ar9.jpg From the left is a Butternut 80/40 vertical then an Imax 2000 (CB antenna) for 10, 12, 15 and also mounted on the back porch a Diamond V2000 for 6, 2, 440. then on the roof is a discone plus some UHF WX transponders. In addition to Cox and Ma Bell were 4kv, 12kv distribution feeders, and above that a 138kv tie line (not visible in pic). All of that wire either radiated its own noise or parasitically re-radiated noise of the others so it was often, but not always, difficult to get a precise source to use in the phase noise canceler (ANC-4). The TV antenna was useful to get OTA LA stations like KCAL9, SoCal's premier car chase station. g This looks bad, worse than my situation. I just have the local residential feeder out front, probably 12 kv, and a set of parallel feeders in back that probably range up to 138 kv that serves the industrial park 500 feet west of me. I can often reduce noise from one source with my MFJ-1026 (similar to the ANC-4), but just the one. I hate the idea of piling up multiple MFJs and antennae to try to catch all of the sources. There are some high-tension lines out about 1/2 mile west or so, but they are pretty far. They audibly crackle and snap all the time, though, whenever I ride my bike past them. |
Inline Isolators for RFI reduction ?
On Jan 18, 9:34*pm, Bob Dobbs wrote:
bpnjensen wrote: Maybe I'll try to match up the astronomy sessions with the radios. Reminiscent of yesteryear when several friends and I would go up to the local mountains or over to the desert for an evening of various activities, astronomy included. We would routinely take a load of optical gear plus star charts, GPS units plus topo charts, amateur radio gear for tactical coordination, as well as a few firearms, pyrotechnical devices, night vision viewers, and so on. We had met through mutual interest in scanner/SWL activities. BIG sigh - that sounds wonderful! |
Five Basic Steps to Better Shortwave Radio Listening [SWL]
On Jan 19, 1:10*am, Bob Dobbs wrote:
D. Peter Maus wrote: * You sound like you're living in the noise equivalent of the Little Big Horn. Before the last move three years ago I lived close to there. Or so it seemedhttp://img.myph.us/Ar9.jpg From the left is a Butternut 80/40 vertical then an Imax 2000 (CB antenna) for 10, 12, 15 and also mounted on the back porch a Diamond V2000 for 6, 2, 440. then on the roof is a discone plus some UHF WX transponders. In addition to Cox and Ma Bell were 4kv, 12kv distribution feeders, and above that a 138kv tie line (not visible in pic). All of that wire either radiated its own noise or parasitically re-radiated noise of the others so it was often, but not always, difficult to get a precise source to use in the phase noise canceler (ANC-4). The TV antenna was useful to get OTA LA stations like KCAL9, SoCal's premier car chase station. g Oh,that's why some people started using alumium siding ! It is almost a Faraday cage... |
Five Basic Steps to Better Shortwave Radio Listening [SWL]
bpnjensen wrote: On Jan 18, 10:10 pm, Bob Dobbs wrote: D. Peter Maus wrote: You sound like you're living in the noise equivalent of the Little Big Horn. Before the last move three years ago I lived close to there. Or so it seemedhttp://img.myph.us/Ar9.jpg From the left is a Butternut 80/40 vertical then an Imax 2000 (CB antenna) for 10, 12, 15 and also mounted on the back porch a Diamond V2000 for 6, 2, 440. then on the roof is a discone plus some UHF WX transponders. In addition to Cox and Ma Bell were 4kv, 12kv distribution feeders, and above that a 138kv tie line (not visible in pic). All of that wire either radiated its own noise or parasitically re-radiated noise of the others so it was often, but not always, difficult to get a precise source to use in the phase noise canceler (ANC-4). The TV antenna was useful to get OTA LA stations like KCAL9, SoCal's premier car chase station. g This looks bad, worse than my situation. I just have the local residential feeder out front, probably 12 kv, and a set of parallel feeders in back that probably range up to 138 kv that serves the industrial park 500 feet west of me. I can often reduce noise from one source with my MFJ-1026 (similar to the ANC-4), but just the one. I hate the idea of piling up multiple MFJs and antennae to try to catch all of the sources. There are some high-tension lines out about 1/2 mile west or so, but they are pretty far. They audibly crackle and snap all the time, though, whenever I ride my bike past them. You need to flee your present location. Karl Knows |
Clamp On RF Choke Stops Noise on AC Mains
On 01/18/2011 07:59 PM, bpnjensen wrote:
Thanks, Peter - This may be all true - but for the record, with the radios plugged in, I disconnected the antennas and kept the grounds connected. The radios got very quiet; based on this, I don't think it's the mains. FWIW, I have an RFI filter on the 115 VAC - this item: ICE: http://www.iceradioproducts.com/imag...ersarticle.pdf The difference between using it and not using it is slight, but noticeable. http://www.radioshack.com/product/in...ductId=2103222 [read reviews] |
Five Basic Steps to Better Shortwave Radio Listening [SWL]
On 01/18/2011 08:03 PM, bpnjensen wrote:
Thanks - Maybe, but I think ferrites on the RF cables might be more critical than on the power cables. The radios are nice and quite when I disconnect the antennae; no noise level at all even with the multiple preamps all the way up. Maybe you should just use 50 Ohm resistors in lieu of antennas. Very low VSWR; should work great. |
Five Basic Steps to Better Shortwave Radio Listening [SWL]
On 01/18/2011 10:10 PM, Bob Dobbs wrote:
The TV antenna was useful to get OTA LA stations like KCAL9, SoCal's premier car chase station.g KCAL is where KCBS puts all their ghetto stuff. |
Five Basic Steps to Better Shortwave Radio Listening [SWL]
|
Five Basic Steps to Better Shortwave Radio Listening [SWL]
On Jan 19, 12:10*am, wrote:
On Jan 19, 1:10*am, Bob Dobbs wrote: D. Peter Maus wrote: * You sound like you're living in the noise equivalent of the Little Big Horn. Before the last move three years ago I lived close to there. Or so it seemedhttp://img.myph.us/Ar9.jpg From the left is a Butternut 80/40 vertical then an Imax 2000 (CB antenna) for 10, 12, 15 and also mounted on the back porch a Diamond V2000 for 6, 2, 440. then on the roof is a discone plus some UHF WX transponders. In addition to Cox and Ma Bell were 4kv, 12kv distribution feeders, and above that a 138kv tie line (not visible in pic). All of that wire either radiated its own noise or parasitically re-radiated noise of the others so it was often, but not always, difficult to get a precise source to use in the phase noise canceler (ANC-4). The TV antenna was useful to get OTA LA stations like KCAL9, SoCal's premier car chase station. g - Oh,that's why some people started using alumium - siding ! It is almost a Faraday cage... A Faraday Cage {Copper Kettle} works both ways. |
Five Basic Steps to Better Shortwave Radio Listening [SWL]
On Jan 18, 2:05*pm, bpnjensen wrote:
On Jan 18, 10:57*am, John Smith wrote: On 1/18/2011 10:44 AM, bpnjensen wrote: ... Actually, no, and I am sorry if there was a misunderstanding - I meant an inline (in the coax) RFI reduction system. Baluns/ununs really are NOT an RFI reduction system. *They provide proper impedance matching between antenna and feedline. *Coax, with an rf choke (can be a balun/unun) allows the feedline to run though noisy areas and not pick up the noise there, such as when it enters a house with noise present. Baluns/ununs/rf-transformers, because of the use in gaining a superior match (transfer of signal energy) improves signal to noise ratio, in most instances, and this can appear to be functioning as a "RFI reduction system." Some useful links:http://users.belgacom.net/hamradio/s...ongwire%20Balu... Regards, JS OK, understood, but I have always thought (based on what I have read) that one of these matching transformers, properly deisgned and grounded, can bleed off some noise to ground. *Am I misled? The 'concept' is that the Feed-in-Line "Inline Isolator" [1:1 Transformer] is in the Radio Shack -or- at the point the Feed-in-Line enters the House/Building. Mount the "Inline Isolator" directly on a Ground Rod right outside the Radio Shack Window. http://www.wellbrook.uk.com/longwire.html Placement at this point prevents the AC Line Noise and other RFI Noises in the House from 'migrating' out along the Coax to the Antenna|End; and then ?reflecting? back from the Antenna along the Coax back into the Radio Shack and into the Radio/Receiver. iane ~ RHF |
Common mode noise reduction/elimination.
On 1/16/2011 11:24 AM, bpnjensen wrote:
Question to those who may have used one - Do inline isolators work well on RX? Such as those sold by Radioworks? Thanks, Bruce Jensen It sounds like, if you use an outdoor antenna, you need a 9:1 balun/unun (depending on antenna design/length) at the point where the feed line feeds the antenna, with the shield grounded at this point to a good earth ground. Next, a 1:1 unun (50 to 50, or 75 to 75, ohm) between the coax and the receiver, with a good earth ground on the receiver. This should remove any common mode noise on the shield of the coax. This is what I use ... If you use a balanced antenna, you need a balun at the feedline where it feeds the antenna, if you use a longwire/unbalanced-antenna, you need a unun at this point. Regards, JS |
Five Basic Steps to Better Shortwave Radio Listening [SWL]
On 01/19/2011 12:46 PM, D. Peter Maus wrote:
But mix products are difficult to track down, let alone eliminate. You'll need to find, and isolate the point at which rectification is taking place, and that could be ANYWHERE...wherever metal components in any structure touch, you can get rectification, which will product mix products from the environmental RF. It took me a couple of years to finally track down and eliminate the mix products being generated on my property. Padding down the antenna input also helped. You really ARE in the Little Big Horn for noise and interference. A 20 dB pad will help the swamping. Have you tried an MFJ-956 preselector? |
Clamp On RF Choke Stops Noise on AC Mains
On 01/20/2011 03:40 AM, RHF wrote:
hope this helps - iane ~ RHF . . You need mix #43 for HF |
Five Basic Steps to Better Shortwave Radio Listening [SWL]
On Jan 20, 10:08*am, dxAce wrote:
bpnjensen wrote: On Jan 19, 2:24 pm, dave wrote: On 01/19/2011 12:46 PM, D. Peter Maus wrote: But mix products are difficult to track down, let alone eliminate. You'll need to find, and isolate the point at which rectification is taking place, and that could be ANYWHERE...wherever metal components in any structure touch, you can get rectification, which will product mix products from the environmental RF. It took me a couple of years to finally track down and eliminate the mix products being generated on my property. Padding down the antenna input also helped. You really ARE in the Little Big Horn for noise and interference. A 20 dB pad will help the swamping. Have you tried an MFJ-956 preselector? Not yet, but I've been thinking about a preselector. *Does the MFJ work well? Save your money until you find out definitively whether your RFI is actually coming in internally or externally, and if it is external, the ONLY way to resolve that issue is trying to get something done with your local power provider. Elsewise... flee- Hide quoted text - - Show quoted text - I don't disagree - but it may be that the only way to determine whether the problem is internal vs. external is by spending at least a few $$. I can do this. |
Inline Isolators for RFI reduction ?
On Jan 16, 11:24*am, bpnjensen wrote:
Question to those who may have used one - Do inline isolators work well on RX? *Such as those sold by Radioworks? Thanks, Bruce Jensen I do wish to say at this point that I greatly appreciate the interest and information on this thread. I feel like I may be able to make some headway, even if toward nothing else than a better understanding of the local problems. Thanks to everyone... BJ |
Inline Isolators for RFI reduction ?
On 1/20/2011 3:59 PM, bpnjensen wrote:
On Jan 16, 11:24 am, wrote: Question to those who may have used one - Do inline isolators work well on RX? Such as those sold by Radioworks? Thanks, Bruce Jensen I do wish to say at this point that I greatly appreciate the interest and information on this thread. I feel like I may be able to make some headway, even if toward nothing else than a better understanding of the local problems. Thanks to everyone... BJ Are they current ununs or voltage ununs? Current "baluns" should be fine ... Regards, JS |
Clamp On RF Choke Stops Noise on AC Mains
On Jan 20, 8:13*am, dave wrote:
On 01/20/2011 03:40 AM, RHF wrote: hope this helps - iane ~ RHF * . * . - You need mix #43 for HF Dave : I think that the manufactures of the commonly available Clamp-On Ferrite Cores know that. ~ RHF |
Five Basic Steps to Better Shortwave Radio Listening [SWL]
On 01/20/2011 03:57 PM, bpnjensen wrote:
I used to live on the Southeast Corner of Peden and Van Buren in Houston, TX. We had 72KV, 36KV, and residential feeder, all aerial. This was the era of cheap dimmers, CRT televisions, etc. I had a lot of good DXing from that house. |
Why an Antenna Tuner May Be A Waste of Money -by- Daniel A Grunberg
On 1/20/2011 4:55 PM, RHF wrote:
... BpnJ -read- Why an Antenna Tuner May Be A Waste of Money http://www.hard-core-dx.com/nordicdx...l/notuner.html -by- Daniel A Grunberg -source--@- Hard Core DX .Com ... In the country, noise is low. At my present location there is moderate manmade noise, with a 120 ft antenna, ~35 ft in the air, a long wire with a 9:1 unun at the antenna and a 1:1 unun at the rig, I find the tuner invaluable. Sure, it is only useful on signals where the broadcast signal is greater than the the noise level, but then, so is everything else, including the receiver, only useful then ... other than noise elimination circuitry on the more expensive models ... some DSP actually works, and works well. Regards, JS |
Inline Isolators for RFI reduction ?
On 1/20/11 17:59 , bpnjensen wrote:
On Jan 16, 11:24 am, wrote: Question to those who may have used one - Do inline isolators work well on RX? Such as those sold by Radioworks? Thanks, Bruce Jensen I do wish to say at this point that I greatly appreciate the interest and information on this thread. I feel like I may be able to make some headway, even if toward nothing else than a better understanding of the local problems. Thanks to everyone... BJ Wait till you get our bill. |
Why an Antenna Tuner May Be A Waste of Money -by- Daniel A Grunberg
On Jan 20, 5:03*pm, John Smith wrote:
On 1/20/2011 4:55 PM, RHF wrote: ... BpnJ -read- Why an Antenna Tuner May Be A Waste of Money http://www.hard-core-dx.com/nordicdx...l/notuner.html -by- Daniel A Grunberg -source--@- Hard Core DX .Com ... In the country, noise is low. *At my present location there is moderate manmade noise, with a 120 ft antenna, ~35 ft in the air, a long wire with a 9:1 unun at the antenna and a 1:1 unun at the rig, I find the tuner invaluable. *Sure, it is only useful on signals where the broadcast signal is greater than the the noise level, but then, so is everything else, including the receiver, only useful then ... other than noise elimination circuitry on the more expensive models ... some DSP actually works, and works well. Regards, JS John, I used to live in rural Massachusetts, and it was dreamy - quiet backgrounds, all sorts of SA and CA DX all the time on the tropical bands. I didn't even have the baluns - just a straight wire hooked to Realistic Astronaut-8 and a Hammarlund HQ-100. No powerful radio stations nearby, no industries, It was all good. My SX-190 has a preselector on it, and it works quite well (although the radio is *very* sensitive to intermod on 31 meters). My DX-160 has a "trimmer" tuner, and again, it works quite well - in some cases it even has the ability to knock down an adjacent signal enough to render it inconsequential. The Icom's filters are good enough so these kinds of things are not too important, but a preselector might be nice once in awhile. The Icom has a built-in DSP, not like the Timewave's, but sufficient to reduce the background crapola. |
Inline Isolators for RFI reduction ?
On Jan 20, 4:06*pm, John Smith wrote:
On 1/20/2011 3:59 PM, bpnjensen wrote: On Jan 16, 11:24 am, *wrote: Question to those who may have used one - Do inline isolators work well on RX? *Such as those sold by Radioworks? Thanks, Bruce Jensen I do wish to say at this point that I greatly appreciate the interest and information on this thread. I feel like I may be able to make some headway, even if toward nothing else than a better understanding of the local problems. *Thanks to everyone... BJ Are they current ununs or voltage ununs? Current "baluns" should be fine ... Regards, JS I *think* they are current ununs; they advertise then as being designed to stop stray RF from a transmitter from descending the outer conductor. The person there says that they have no effect on RX, which is odd considering they'd probably like to sell the things - but she is the only one I have spoken with who says that RX is not affected. Many other sell them expressly for this purpose. |
Inline Isolators for RFI reduction ?
On Jan 20, 5:58*pm, "D. Peter Maus" wrote:
On 1/20/11 17:59 , bpnjensen wrote: On Jan 16, 11:24 am, *wrote: Question to those who may have used one - Do inline isolators work well on RX? *Such as those sold by Radioworks? Thanks, Bruce Jensen I do wish to say at this point that I greatly appreciate the interest and information on this thread. I feel like I may be able to make some headway, even if toward nothing else than a better understanding of the local problems. *Thanks to everyone... BJ * *Wait till you get our bill. Wait a minute - where's that Lotto ticket...? |
Five Basic Steps to Better Shortwave Radio Listening [SWL]
On Jan 20, 7:29*pm, dave wrote:
On 01/20/2011 03:57 PM, bpnjensen wrote: I used to live on the Southeast Corner of Peden and Van Buren in Houston, TX. We had 72KV, 36KV, and residential feeder, all aerial. This was the era of cheap dimmers, CRT televisions, etc. I had a lot of good DXing from that house. Don't forget about the soil conductivity- sometimes it helps greatly. |
Inline Isolators for RFI reduction ?
On Jan 20, 9:09*pm, bpnjensen wrote:
On Jan 20, 5:58*pm, "D. Peter Maus" wrote: On 1/20/11 17:59 , bpnjensen wrote: On Jan 16, 11:24 am, *wrote: Question to those who may have used one - Do inline isolators work well on RX? *Such as those sold by Radioworks? Thanks, Bruce Jensen I do wish to say at this point that I greatly appreciate the interest and information on this thread. I feel like I may be able to make some headway, even if toward nothing else than a better understanding of the local problems. *Thanks to everyone... BJ * *Wait till you get our bill. Wait a minute - where's that Lotto ticket...?- Hide quoted text - - Show quoted text - Make sure Cuhoo's doggy didn't eat it. And, incidentally Mass. has very good anomalies as far as HF is concerned . Scituate location's conditions are quite favorable and it was a site of a major SW transmitter for many years . |
Why an Antenna Tuner May Be A Waste of Money -by- Daniel A Grunberg
On 1/21/2011 1:00 AM, Bob Dobbs wrote:
John Smith wrote: other than noise elimination circuitry on the more expensive models ... some DSP actually works, and works well. Seems to me that DSP NR is basically a glorified treble control, initializes to the background and ignores the variations (voice) In real DSP, the audio is processed by a CPU, it is "examined." And, noise is attempted to be "identified." One example, the human voice has slow rise and fall times, generally, on pronunciation and sound formation, where noise has fast attack and delay speeds. As patents expire, we may see decent circuitry on even moderately priced and cheap receivers. Regards, JS |
Why an Antenna Tuner May Be A Waste of Money -by- Daniel A Grunberg
On 1/22/2011 3:25 AM, D. Peter Maus wrote:
... You are correct. I commonly see one unit called both, such as this example: http://www.eham.net/reviews/detail/3912 Regards, JS |
Why an Antenna Tuner May Be A Waste of Money -by- Daniel A Grunberg
On Jan 22, 12:08*pm, John Smith wrote:
On 1/22/2011 3:25 AM, D. Peter Maus wrote: ... You are correct. I commonly see one unit called both, such as this example:http://www.eham..net/reviews/detail/3912 Regards, JS Some of the reviews praise the MFJ 956 for its LW and MW capabilities . |
Why an Antenna Tuner May Be A Waste of Money -by- Daniel A Grunberg
On 01/22/2011 08:34 PM, bpnjensen wrote:
JS MFJ makes two items that they describe specifically as preselectors, the 1046 and 1048 - one "passive" and one powered. The passive has fewer parts, but the instructions at the MFJ site blithely suggest that both do a great job. They advertise the 956 as a tuner. Tuner is used more generically here. A preselector is a type of tuner. |
Why an Antenna Tuner May Be A Waste of Money -by- Daniel A Grunberg
On 01/22/2011 10:59 PM, Bob Dobbs wrote:
bpnjensen wrote: I always thought that the word ''tuner" referred to tunable circuitry designed to match a transmitter to an antenna whereas "preselector" is most often used with lower power levels as is typical with antennas for receivers. They both work as tunable bandpass circuits with the "tuners" generally having a lower Q. My old Grove TUN-3 (preselector) has much sharper (selective) tuning whereas the MFJ-949E (tuner) has a wider frequency range of bandpass. If you have a 30 turn coil, a 365 mfd variable capacitor, and a couple clip leads you can build a "L" matcher, that will tune just about anything. Another junk pile solution... |
| All times are GMT +1. The time now is 08:50 PM. |
|
Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
RadioBanter.com