Re: Topband: Artificial Propagation...?
As I remember the earlier project, it was an effort in the early or mid 1960s to create perpetual worldwide twilight by shooting millions of tiny copper needles into the upper atmosphere. I remember reading at the time that they became magnetized and stuck together for that reason. In any event, instead of dispersing, they orbitted for awhile as a large clump. --Art Delibert, KB3FJO From: n...@cox.net To: k...@frontier.com; topband@contesting.com Date: Sat, 10 Mar 2012 21:13:45 -0700 Subject: Re: Topband: Artificial Propagation...? Carl, I thought someone, maybe NASA tried this many years ago and their folley was that the universal gravitational force equation did in the whole project because once 2 particles attach to one another that doubles the mass. After that, a 3rd joins the double, and then a 4th, and so on until you have this big bunch needles doing nothing but orbiting the Earth. I don't see that this is any different. 73 Hardy N7RT - Original Message - From: k...@frontier.com To: topband@contesting.com Sent: Saturday, March 10, 2012 7:10 PM Subject: Re: Topband: Artificial Propagation...? But more importantly, 100 km is too low to provide much help to us Topbanders. This is far below the E and F layers of the ionosphere that we rely on for DX. The peak of the nighttime E region is around 110 km, so 100 km is not too far below the E region. The lower E region is also where most absorption at night occurs on 160m. More to the point, refraction is inversely proportional to the square of the frequency. An electromagnetic wave at 1.8 MHz bends more and doesn't get as high into the ionosphere as our HF (3-30 MHz) energy. At night, with the E region critical frequency around 0.4 MHz, energy at elevation angles lower than about 5 degrees is refracted back to Earth by the E region. Thus the E region may be more important than we normally think. Carl K9LA ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: How Good is Good Enough?
I have about 350 feet of quad-shield RG-6 going out to a receiving antenna hub which has a 20-db ARR preamp on the end of the line, followed by an 8-way relay switch. The feedline is lying on the ground, or more correctly on the stubble of a mowed hayfield. At the moment, it has only one BOG on it, but I plan to add other BOGs and a K9AY loop for some comparative tests. The feedline has a center tapped common mode choke about 15 feet from the hub, a la ON4UN and K9YC references - 14 turns of RG-6 on each of 2 #31 toroids. My question is this. If I disconnect the one BOG, and listen to the feedline and preamp, how quiet should it be? How would I go about testing its quietness? If it is not quiet enough in this configuration, what would my next step be? Another common mode choke at the shack entrance? -- 73, Pete N4ZR The World Contest Station Database, updated daily at www.conteststations.com The Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com, spots at telnet.reversebeacon.net, port 7000 and arcluster.reversebeacon.net, port 7000 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Artificial Propagation...?
Some of you may be thinking of Project West Ford, conducted in the early 1960's by MIT Lincoln Laboratory (where I work now). Many millions of tiny needles were launched into orbit to generate an artificial scattering medium above the earth for long range microwave communications. You must remember that this was at a time when there were no communications satellites or long-haul fiberoptic networks, which we take for granted today. Technically the project was a success as it demonstrated microwave links from the east coast to west coast. However, it required very large ground terminals with very high transmitter power. Eventually interest in the concept died after the first communications satellites were deployed. Most of the needles eventually re-entered the atmosphere and disappeared, although I understand a few still remain in orbit. See: http://en.wikipedia.org/wiki/Project_West_Ford and http://www.damninteresting.com/earths-artificial-ring-project-west-ford/ for more information. 73, John W1FV -Original Message- From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com] On Behalf Of Arthur Delibert Sent: Sunday, March 11, 2012 7:59 AM To: n...@cox.net; k...@frontier.com; topband@contesting.com Subject: Re: Topband: Artificial Propagation...? As I remember the earlier project, it was an effort in the early or mid 1960s to create perpetual worldwide twilight by shooting millions of tiny copper needles into the upper atmosphere. I remember reading at the time that they became magnetized and stuck together for that reason. In any event, instead of dispersing, they orbitted for awhile as a large clump. --Art Delibert, KB3FJO ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Artificial Propagation...?
Thanks John. There's an interesting article about Project West Ford on Wikipedia, which describes the failed 1961 launch (the one I remember), and the successful 1963 launch. Apparently, radio astronomers and others (including the Soviets, of course) protested, and the project ultimately led to a provision on international consultation in the 1967 Space Treaty. --Art Delibert, KB3FJO From: john.kaufm...@verizon.net To: topband@contesting.com Date: Sun, 11 Mar 2012 11:45:01 -0400 Subject: Re: Topband: Artificial Propagation...? Some of you may be thinking of Project West Ford, conducted in the early 1960's by MIT Lincoln Laboratory (where I work now). Many millions of tiny needles were launched into orbit to generate an artificial scattering medium above the earth for long range microwave communications. You must remember that this was at a time when there were no communications satellites or long-haul fiberoptic networks, which we take for granted today. Technically the project was a success as it demonstrated microwave links from the east coast to west coast. However, it required very large ground terminals with very high transmitter power. Eventually interest in the concept died after the first communications satellites were deployed. Most of the needles eventually re-entered the atmosphere and disappeared, although I understand a few still remain in orbit. See: http://en.wikipedia.org/wiki/Project_West_Ford and http://www.damninteresting.com/earths-artificial-ring-project-west-ford/ for more information. 73, John W1FV -Original Message- From: topband-boun...@contesting.com [mailto:topband-boun...@contesting.com] On Behalf Of Arthur Delibert Sent: Sunday, March 11, 2012 7:59 AM To: n...@cox.net; k...@frontier.com; topband@contesting.com Subject: Re: Topband: Artificial Propagation...? As I remember the earlier project, it was an effort in the early or mid 1960s to create perpetual worldwide twilight by shooting millions of tiny copper needles into the upper atmosphere. I remember reading at the time that they became magnetized and stuck together for that reason. In any event, instead of dispersing, they orbitted for awhile as a large clump. --Art Delibert, KB3FJO ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: Signal pickup mystery
Please pardon my repeating myself, but this thing has really got me buffaloed, and I've found that this is the place where the most knowledgeable people about this sort of thing hang out I am feeding DC down my feedline to the ARR preamp in the RX antenna hub, and also to the relays and the logic inside it (my cheapo Chinese relay board). I now have the hub sitting out there with no antenna connected, so it is effectively just the preamp and the relays on the end of the coax, plus common mode pickup on the coax. On 1550 KHz (my local 70-over-9 broadcast station), this combination is 70 dB down as compared to my 160M shunt fed tower. However, if I go up to 20 meters and find a strong station, then the feedline-cum-hub combination receives about as well as the tower, and is only ~20 dB down from a single small tribander. Now here's the mysterious part. If I remove the DC power from the preamp, the 20-meter signals drop from S9 to barely audible. This is also noticeable, but just barely, on the 1550 KHz signal. Is it possible that the preamp, which is between the feedline and the primary of the binocular matching transformer, is somehow amplifying the common mode signals? The shield of the coax connects to the shell of the preamp, and from there to the secondary of the matching transformer (the 75-ohm side). Is it possible that common mode signals are getting back into the preamp input through the matching transformer primary? If so, any ideas on how to clean it up? Or should I just get rid of the preamp out there and do my amplifying in the shack? -- 73, Pete N4ZR The World Contest Station Database, updated daily at www.conteststations.com The Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com, spots at telnet.reversebeacon.net, port 7000 and arcluster.reversebeacon.net, port 7000 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: Signal pickup mystery
Hello Pete, Now here's the mysterious part. If I remove the DC power from the preamp, the 20-meter signals drop from S9 to barely audible. This is also noticeable, but just barely, on the 1550 KHz signal. Is it possible that the preamp, which is between the feedline and the primary of the binocular matching transformer, is somehow amplifying the common mode signals? The shield of the coax connects to the shell of the preamp, and from there to the secondary of the matching transformer (the 75-ohm side). Is it possible that common mode signals are getting back into the preamp input through the matching transformer primary? If so, any ideas on how to clean it up? Or should I just get rid of the preamp out there and do my amplifying in the shack? It seems to me that your preamplifier is amplifying whatever it is being fed. A common mode problem would likely be after the preamp and in the feed-line with no connections to the relay box. You could certainly prove this by removing the input to the preamp and replacing it with a termination. Power up and look at the signal levels. I am more inclined to think the signal is being introduced into the preamp by your relay box. Does the relay box short or terminate unused inputs, or are they allowed to float? If they float the contact capacitance could inject signals into the output. Have you terminated the active input? You could try shorting all the inputs to see if the signal is being picked up by the open inputs. Also the power supplied to the relay box could inject signal by the coil to contact capacitance. Do the signals go away if you remove the power to the relay box while leaving the preamp active? Maybe these tests will provide more clues. Lee K7TJR ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: Signal pickup mystery
Replies interspersed - thanks for all the ideas. 73, Pete N4ZR The World Contest Station Database, updated daily at www.conteststations.com The Reverse Beacon Network at http://reversebeacon.net, blog at reversebeacon.blogspot.com, spots at telnet.reversebeacon.net, port 7000 and arcluster.reversebeacon.net, port 7000 On 3/11/2012 4:47 PM, Lee K7TJR wrote: Hello Pete, Now here's the mysterious part. If I remove the DC power from the preamp, the 20-meter signals drop from S9 to barely audible. This is also noticeable, but just barely, on the 1550 KHz signal. Is it possible that the preamp, which is between the feedline and the primary of the binocular matching transformer, is somehow amplifying the common mode signals? The shield of the coax connects to the shell of the preamp, and from there to the secondary of the matching transformer (the 75-ohm side). Is it possible that common mode signals are getting back into the preamp input through the matching transformer primary? If so, any ideas on how to clean it up? Or should I just get rid of the preamp out there and do my amplifying in the shack? It seems to me that your preamplifier is amplifying whatever it is being fed. A common mode problem would likely be after the preamp and in the feed-line with no connections to the relay box. You could certainly prove this by removing the input to the preamp and replacing it with a termination. Power up and look at the signal levels. Excellent idea. Easy to do, also. I am more inclined to think the signal is being introduced into the preamp by your relay box. Does the relay box short or terminate unused inputs, or are they allowed to float? They are grounded. If they float the contact capacitance could inject signals into the output. Have you terminated the active input? You could try shorting all the inputs to see if the signal is being picked up by the open inputs. Also the power supplied to the relay box could inject signal by the coil to contact capacitance. Do the signals go away if you remove the power to the relay box while leaving the preamp active? All good thoughts! Maybe these tests will provide more clues. Lee K7TJR ___ UR RST IS ... ... ..9 QSB QSB - hw? BK ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: How Good is Good Enough?
How does the signal level from a BOG compare to the signal level from an elevated Beverage? I'm sure the output from a BOG is less. But how much less? Enough to require a remote preamp? I've always wondered. I --and many others-- have found a remote preamp on an *elevated* Beverage to be totally unnecessary, even with the lossy matching transformers that I used in the past. The only DC I ever run down my ~600' of RG-6 feeding a Beverage is to reverse directions. 73, Mike www.w0btu.com On Sun, Mar 11, 2012 at 8:50 AM, Pete Smith N4ZR n...@contesting.comwrote: I have about 350 feet of quad-shield RG-6 ... it has only one BOG on it ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: How Good is Good Enough?
Ive said several times that my 500' BOG's dont need a preamp. The signal level may be 5-6dB lower than the elevated ones in the same direction but thats more likely due to signal angle. One or two on here keep claiming 500' wont work and I say it all depends upon the ground.mine is about as poor as you can get. For best performance you need to know your RF ground resistance and wind the transformer accordingly. I used 250 Ohms for the ground. Carl KM1H - Original Message - From: Mike Waters mikew...@gmail.com To: topband topband@contesting.com Sent: Sunday, March 11, 2012 6:12 PM Subject: Re: Topband: How Good is Good Enough? How does the signal level from a BOG compare to the signal level from an elevated Beverage? I'm sure the output from a BOG is less. But how much less? Enough to require a remote preamp? I've always wondered. I --and many others-- have found a remote preamp on an *elevated* Beverage to be totally unnecessary, even with the lossy matching transformers that I used in the past. The only DC I ever run down my ~600' of RG-6 feeding a Beverage is to reverse directions. 73, Mike www.w0btu.com On Sun, Mar 11, 2012 at 8:50 AM, Pete Smith N4ZR n...@contesting.comwrote: I have about 350 feet of quad-shield RG-6 ... it has only one BOG on it ___ UR RST IS ... ... ..9 QSB QSB - hw? BK - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1424 / Virus Database: 2113/4865 - Release Date: 03/11/12 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Re: Topband: How Good is Good Enough?
Very possible on your farm Mike, time to experiment I'd say. Carl KM1H - Original Message - From: Mike Waters mikew...@gmail.com To: topband topband@contesting.com Sent: Sunday, March 11, 2012 9:19 PM Subject: Re: Topband: How Good is Good Enough? Thanks, Carl! Seems to me that laying on the ground, the VF would be considerably lower, and so we could shorten them. 73, Mike www.w0btu.com On Sun, Mar 11, 2012 at 7:58 PM, ZR z...@jeremy.mv.com wrote: Ive said several times that my 500' BOG's dont need a preamp. The signal level may be 5-6dB lower ___ UR RST IS ... ... ..9 QSB QSB - hw? BK - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1424 / Virus Database: 2113/4865 - Release Date: 03/11/12 ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
Topband: N3BB's Novel
I'd bet that a lot of folks who hang out here know Jim George, N3BB.I've just finished reading his novel, and it's a real page-turner. It's the story of a guy sort of like a lot of us techie types growing up in a town in West Virginia in the 50s. The protagonist discovers ham radio, gets involved in the pop music scene, high school sports, girls, the beginnings of school integration the civil rights movement, and his struggles with issues with one of his parents. The story begins as he prepares to attend a high school reunion, then flashes back to his high school days where much of the story is told. I really enjoyed it, and found that it touched me in many ways. Strongly recommended. http://www.amazon.com/Reunion-James-Kennedy-George-Jr/dp/1468529684/ref=cm_cr_pr_product_top This is off topic, so please don't start a discussion about it. 73, Jim K9YC ___ UR RST IS ... ... ..9 QSB QSB - hw? BK
