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#1
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Thanks for your reply Dave,
I'm learning a lot in a hurry, finding out that grounds can be just as complex as antennas, and all about the interelationship between the two. I do have chokes on the power cord of my 12v supply and also on the supply cord between the PS and the rig. Your half wave suggestion is not immediately forthcoming due to the physical limitations I face here however it is on my list of possible future condierations. As per a previous post I have recently come into a treasure trove of inductors and capacitors -- variables of every type and sixe. With all this at my disposalI plan to fiddle about with tunable counterpoises, artificial grounds, and combinations thereof. At least I'm on the air again, but because I gave all my gear away I've had to jump from old tube rigs into a QRP world with a teensy Yaesu Ft-817 that it appears will take some time to learn to operate with all its menus, settings, and such. I have to get new glasses and perhaps a magnifier too. The saving grace here is QRP with which I hope to get into as little trouble as possible. I'm a pretty good tech, and have fixed up and modified lots of stuff but now I'm going to have to do a lot of learning in the wild world of wire antennas and grounds. Thanks for your good suggestions, and for taking the time to reply. 73 Irv VE6BP "Dave Platt" wrote in message ... In article , Irv Finkleman wrote: I am not as concerned about a case of 'rf lip' as I am about stray RF causing possible problems with the neighbours on all sides of me, with all my electronic toys such as computers, DVD players, the local fire-alarm system and other such things. The last thing I want to do is draw attention to the fact that I am running a ham radio station from my suite until I know I am not causing any problems. Thusly, my goal is to provide myself with a first rate RF ground system, entirely contained within my suite, in order that I do not wake up at night with the fire alarms set off and great numbers of disturbed residents gathered around pointing at me and saying 'Ham! Ham! For Shame! For Shame!' and the Residents Council having special meetings to decide how to deal with me. They already think I'm crazy -- and I may be somewhat, but I don't want to make matters worse! So, having herein explained my rational, lets see what help I can get in the way of producing the ideal indoor low-cost non-radiating counterpoise radial system. Irv, Your goals are certainly valid. As far as preventing RF from going where you don't want it to... the main issue MJF is talking about here is "conducted" RF. The RF energy on the "ground" side of your antenna connector is going to flow outwards through every conductive path available to it, including the "counterpoise" side of your antenna arrangement, and anything connected directly or indirectly to your rig's chassis (e.g. to the power supply and then onto the third "ground" wire in the household mains). The amount of current flowing through each of these paths will depend on the RF impedance of the path, with more current flowing through paths of lower impedance. So, what you want is (probably) to have one or more counterpoise wires whose RF impedance is as low as practical, at the frequency in question. These could be quarter-wave wires, or they could be shorter or longer wires with an "active ground" (which is essentially a simple "antenna tuner" on the ground side, with an adjustable reactance to cancel out some of the reactance of a non-quarterwave wire). You can also help keep RF "where it belongs" by adding common-mode chokes to your rig power cables, thus increasing the RF impedance of this path and helping reduce the amount of current which is conducted back into the building ground. Another approach which may help, is to consider using an end-fed half-wave antenna, with a specifically-wound matching coil system. These are (in principle at least) largely ground-independent... the low-impedance side of the matching coil provides good RF paths for both the "hot" and "ground" sides of the antenna connection, and when properly adjusted they don't dump much RF into the rig ground or counterpoise. These techniques may not help much, if at all, with *radiated* RF getting into places you don't want it. Even if you have an antenna which is fully balanced, and completely isolated from the building ground (e.g. battery powered), the "near field" RF from the antenna can be coupled into the building wiring, and start causing interference and "undesired operation". Unfortunately, a lot of consumer and industrial electronic equipment these days is very vulnerable to this... poor shielding/filtering. Speaker cables, telephone and alarm wiring, etc. can all act as antennas. Not much you can do about this except try to route your antenna and counterpoise wires as far away from other wiring as possible, keep your transmission power down, and try to transmit during times when people are asleep. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
#2
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On Wed, 25 Apr 2012 19:55:47 -0600, "Irv Finkleman"
wrote: At least I'm on the air again, but because I gave all my gear away I've had to jump from old tube rigs into a QRP world with a teensy Yaesu Ft-817 that it appears will take some time to learn to operate with all its menus, settings, and such. I have to get new glasses and perhaps a magnifier too. Light reading on the FT-817: http://www.ka7oei.com/ft817pg.shtml The saving grace here is QRP with which I hope to get into as little trouble as possible. As soon as the neighbors find out that you're a ham radio operator, several things will happen. 1. You will immediatly be blamed for all manner of electronic failures. Kitchen appliances, computer crashes, and prematurely dead batteries will all become your fault. 2. Neighbors will assume that you fix things for free. Training the neighbors to pay for your time will be a challenge. 3. The phone will ring at 2AM asking if you're on the air and causing reception problems with OTA TV, cable TV, satellite TV, etc. I'm a pretty good tech, and have fixed up and modified lots of stuff but now I'm going to have to do a lot of learning in the wild world of wire antennas and grounds. My theory is that if it doesn't work on paper, it's not going to work when you build it. There are plenty of "standard" antennas that usually work the first time (if you follow instructions). However, you seem to be interested in designing your own. Therefore, I suggest you download the demo version of EZNEC, or the free 4NEC2, and proceed to model your prospective antenna system. When the computah says that you're close, then it's time to build it. An MFJ269 or similar antenna analyzer is handy for verifying your calculations. Hint: One of my ham friends moved into a CC&R (covenants, conditions and restrictions) infested condo farm. No antennas of any kind. The condo council had at least one member that was certain that property values would decline if a ham was allowed to operate from the condo farm. So, I leaned a 20ft aluminum extension ladder against the house and ran a wire to the radio. It worke quite well with a tuner. The ladder was left leaning against the condo for a bit less than a year before the condo council discovered the ruse. There was a short debate. The council decided that since it had been in operation for a year without any complaints or detrimental effects, it could stay. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#3
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![]() "Jeff Liebermann" wrote in message ... snip I leaned a 20ft aluminum extension ladder against the house and ran a wire to the radio. It worke quite well with a tuner. The ladder was left leaning against the condo for a bit less than a year before the condo council discovered the ruse. There was a short debate. The council decided that since it had been in operation for a year without any complaints or detrimental effects, it could stay. -- Jeff Liebermann That is _so_ funny, I just got done mentioning my ladder experience! "Sal" big grin |
#4
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![]() "Jeff Liebermann" wrote in message ... On Wed, 25 Apr 2012 19:55:47 -0600, "Irv Finkleman" wrote: (assorted snips for brevity) Light reading on the FT-817: http://www.ka7oei.com/ft817pg.shtml Already been there and a few other places too, but thanks just the same. There are always new links popping up and I try to keep up with them too! As soon as the neighbors find out that you're a ham radio operator, several things will happen. 1. You will immediatly be blamed for all manner of electronic failures. Kitchen appliances, computer crashes, and prematurely dead batteries will all become your fault. 2. Neighbors will assume that you fix things for free. Training the neighbors to pay for your time will be a challenge. 3. The phone will ring at 2AM asking if you're on the air and causing reception problems with OTA TV, cable TV, satellite TV, etc. After mucho years on the air in mucho locations I can say I've been there, done that! This is however, my first real experience using a very limited antenna and QRP. My theory is that if it doesn't work on paper, it's not going to work when you build it. There are plenty of "standard" antennas that usually work the first time (if you follow instructions). However, you seem to be interested in designing your own. Therefore, I suggest you download the demo version of EZNEC, or the free 4NEC2, and proceed to model your prospective antenna system. When the computah says that you're close, then it's time to build it. An MFJ269 or similar antenna analyzer is handy for verifying your calculations. I have an MFJ-259B -- couldn't live without it, and with all the stuff I gave away this was the one thing that I just couldn't part with. Hint: One of my ham friends moved into a CC&R (covenants, conditions and restrictions) infested condo farm. No antennas of any kind. The condo council had at least one member that was certain that property values would decline if a ham was allowed to operate from the condo farm. So, I leaned a 20ft aluminum extension ladder against the house and ran a wire to the radio. It worke quite well with a tuner. The ladder was left leaning against the condo for a bit less than a year before the condo council discovered the ruse. There was a short debate. The council decided that since it had been in operation for a year without any complaints or detrimental effects, it could stay. Good move! I've always maintained that if you give me any old piece of metal almost anywhere, I'd find a way to load it and get on the air! And I've done it time and time again. I did 26 years in the navy and moved around a lot -- quick and simple antennas were a must! I also helped a lot of chums who moved into condos or rest homes get on the air using similar methods. This case now though, is the first time I ever went into a place that seemed impervious to signals. I've often operated from indoors with no problem, and here, the first time I flashed up the receiver, thought it had gone dead -- that's how bad it was. The first thing I did was checked the protective diodes on the antenna connector and as soon as I found them OK, opened the window and strung a short wire outside -- then everything was 5/9 plus! As per another sailor many years ago said, 'I have not yet begun to fight!' Irv VE6BP |
#5
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On Sun, 29 Apr 2012 16:24:52 -0600, "Irv Finkleman"
wrote: I have an MFJ-259B -- couldn't live without it, and with all the stuff I gave away this was the one thing that I just couldn't part with. For when you transmit into it by accident... http://802.11junk.com/jeffl/pics/2011-12-03-Storm/ The MJF-259B is similar to the MFJ-269B, except that it lacks the 440MHz section. It's a very handy instrument, but is rather fragile in that the detector diodes are connected directly to the RF connector. One blast of too much RF, too much static electricity, or even too much DC, and the diodes go poof. Good move! I've always maintained that if you give me any old piece of metal almost anywhere, I'd find a way to load it and get on the air! There's also the rain gutters. This case now though, is the first time I ever went into a place that seemed impervious to signals. I've often operated from indoors with no problem, and here, the first time I flashed up the receiver, thought it had gone dead -- that's how bad it was. The first thing I did was checked the protective diodes on the antenna connector and as soon as I found them OK, opened the window and strung a short wire outside -- then everything was 5/9 plus! Welcome to the joys of modern energy efficient construction. The walls are full of aluminum foil backed insulation for both thermal and acoustic insulation. The windows are coated with Low-E Titanium Nitride IR reflective coatings (40 ohms per square), which also blocks RF. The roofing material is carbon doped (instead of asbestos) which absorbs RF. The foundation is concrete, which also absorbs RF. Meanwhile, the proliferation of microprocessors, switching power supplies, and BPL like devices, offers multiple sources of QRN. You had it easy at previous locations. As per another sailor many years ago said, 'I have not yet begun to fight!' Fighting is easy. It's negotiation that drives me nuts. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#6
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![]() Welcome to the joys of modern energy efficient construction. The walls are full of aluminum foil backed insulation for both thermal and acoustic insulation. The windows are coated with Low-E Titanium Nitride IR reflective coatings (40 ohms per square), which also blocks RF. The roofing material is carbon doped (instead of asbestos) which absorbs RF. The foundation is concrete, which also absorbs RF. Meanwhile, the proliferation of microprocessors, switching power supplies, and BPL like devices, offers multiple sources of QRN. You had it easy at previous locations. I kind of fell behind in my knowledge of modern constuction. I lived in my house for 29-3/4 years and even though I did a lot of renos, the infrastruction remained basically the same. It is good though that they are getting smart on energy efficient construction and other things -- hopefully we will leave our kids and grandkids with a world pointed in the right direction. As per another sailor many years ago said, 'I have not yet begun to fight!' Fighting is easy. It's negotiation that drives me nuts. I'm on the air but not sure just how well I am getting out, I don't want to measure it, I don't even care to know since it is a whole different matter on QRP. The proof will be in the pudding -- I may have to wait for good band conditions, but the only valid means of measurement will be the number of QSO's and bands I can work. From those lovely boxes of variable caps and assorted inductors (some roller-inductors) and a cheap 2nd hand 50ua meter I am going to build up an artificial ground which is about as simple a circuit as one can get -- the L&C in series and make a sniffer out of the meter and a diode!. I should have it all going in the next day or two -- as soon as I can get a round tooit. Yes. I admit -- I'm a master of procrastination Well, on with the further adventures of getting on the air to the point of satisfaction. Is that a lot, I ask? Thanks on the tips re the MFJ diodes. I'm aware of them and can test and change them if need be. So far, so good! I guess it wouldn't hurt to have some on hand -- it's pretty inevitable that with the experimentation etc, that I'll be doing some or all will get blown before you can say poof! Do you think that if I were to ask the management here If I could have an aluminum ladder outside my second floor window -- just to easy my mind about the dangers of fire, they might agree? Irv VE6BP -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#7
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On Sun, 29 Apr 2012 19:12:01 -0600, "Irv Finkleman"
wrote: It is good though that they are getting smart on energy efficient construction and other things -- hopefully we will leave our kids and grandkids with a world pointed in the right direction. Yep. It's happening, but very slowly and painfully. Ecology is expensive in the short term, but worth the cost and effort. Unfortunately, I've seen some abuse of power precipitated in the name of the environment. Like all good things, environmental correctness does attract a few flies. I'm on the air but not sure just how well I am getting out, I don't want to measure it, I don't even care to know since it is a whole different matter on QRP. Oh rubbish. There are plenty of ways to test your setup that doesn't involve calling CQ and getting a subjective signal report: 1. You can login to one of the remote radios or receivers on the internet, tune to an empty frequency, and listen to yourself. http://beta.remotehams.com http://www.dxzone.com/catalog/Internet_and_Radio/Online_Receivers/ 2. You can join one of the internet QRP clubs. 3. Weak Signal Propagation Reporter Network http://wsprnet.org 4. Reverse Beacon Network: http://www.reversebeacon.net 5. You can listen for beacons to check your receiver and antenna: http://www.ac6v.com/beacons.htm Our local radio club also has a remote HF station controllable over the internet (using HRD) but it's only for club members. From those lovely boxes of variable caps and assorted inductors (some roller-inductors) and a cheap 2nd hand 50ua meter I am going to build up an artificial ground which is about as simple a circuit as one can get -- the L&C in series and make a sniffer out of the meter and a diode!. All an artificial ground does is tune out the ground lead inductance so that it's series resonant at the operating frequency. In effect, you're building a counterpoise. You could user your MFJ-259B or a grid dip meter to resonate the ground lead, and forget about the meter and detector. However, if you must use a meter, I suggest a thermocouple RF ammeter. Getting it to heat up the series resistor at 5 watts might be a challenge, but it can be done. Otherwise, it's a current transfomer, ferrite core, diode detector, and 50ua meter. http://www.w1tag.com/RFA.htm I'm a master of procrastination I have a PHD in procrastination. Never do today what you get someone else to do for you tomorrow. Is that a lot, I ask? Yes, if you try to do it all at once. No, if you take your time, grind the numbers, do a little planning, and invite all your friends to help. Thanks on the tips re the MFJ diodes. I'm aware of them and can test and change them if need be. I could only test the diodes after they were removed. The 50 ohm resistors in the circuit prevented easy checking with an ohms guesser. So far, so good! I guess it wouldn't hurt to have some on hand -- it's pretty inevitable that with the experimentation etc, that I'll be doing some or all will get blown before you can say poof! Yep. My experience is that certain users tend to blow up diodes no matter what they do, while others don't have any problems. I'm sure it's the user, not the analyzer. Possibly static build-up or ungrounded antennas. Dunno. I've been fairly lucky replacing all 4 diodes without needed to calibrate the device. However, if you find the readings off after replacement, see: http://www.w8ji.com/mfj-259b_calibration.htm The procedure took me 2 full days on an MFJ-269B. It went much quicker after I read and followed the instructions. Do you think that if I were to ask the management here If I could have an aluminum ladder outside my second floor window -- just to easy my mind about the dangers of fire, they might agree? No. Someone will probably try to steal the ladder. 20ft ladders are not cheap. I ran two u-bolts through the ladder base, and permanently attached the u-bolts to two foundation blocks with half a bag of concrete mix in the hole. Various attempts were made to steal it, but nobody got very far with 30 kg of buried excess weight attached. The connecting antenna wire also acts as a capacitive alarm when the HF radio is not being used. All this was only possible because each condo had its own private back yard. Another problem with a 2nd floor ladder is that you will be feeding the ladder from the top, rather than from the bottom. That will possibly work, but probably not as good as feeding the ladder from the bottom. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#8
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![]() "Jeff Liebermann" wrote in message ... On Sun, 29 Apr 2012 19:12:01 -0600, "Irv Finkleman" wrote: It is good though that they are getting smart on energy efficient construction and other things -- hopefully we will leave our kids and grandkids with a world pointed in the right direction. (snipped now and again here and there for brevity) I'm on the air but not sure just how well I am getting out, I don't want to measure it, I don't even care to know since it is a whole different matter on QRP. Oh rubbish. There are plenty of ways to test your setup that doesn't involve calling CQ and getting a subjective signal report: 1. You can login to one of the remote radios or receivers on the internet, tune to an empty frequency, and listen to yourself. http://beta.remotehams.com http://www.dxzone.com/catalog/Internet_and_Radio/Online_Receivers/ 2. You can join one of the internet QRP clubs. 3. Weak Signal Propagation Reporter Network http://wsprnet.org 4. Reverse Beacon Network: http://www.reversebeacon.net 5. You can listen for beacons to check your receiver and antenna: http://www.ac6v.com/beacons.htm Our local radio club also has a remote HF station controllable over the internet (using HRD) but it's only for club members. I won't care about subjective reports -- I'll be happy if my few paltry watts that do escape the antenna get me any kind of response. I am aware of the remote receivers but I don't want to get so busy using other things that I won't have time on the air making plain good old fashioned QSOs. I will have a peek at the internet QRP clubs as long as I don't lose on air time going to meetings -- even on-air! From those lovely boxes of variable caps and assorted inductors (some roller-inductors) and a cheap 2nd hand 50ua meter I am going to build up an artificial ground which is about as simple a circuit as one can get -- the L&C in series and make a sniffer out of the meter and a diode!. All an artificial ground does is tune out the ground lead inductance so that it's series resonant at the operating frequency. In effect, you're building a counterpoise. You could user your MFJ-259B or a grid dip meter to resonate the ground lead, and forget about the meter and detector. I considered that. I already have a group of radials of various lengths on the floor -- I tied them together with plastic ties for neatness, but with a ground tuner I only need one which I plan to lay out along the edge of the carpet -- that should make a neater job and if I can tuck most of it under the baseboards it will not frighten the houskeeper. However, if you must use a meter, I suggest a thermocouple RF ammeter. Getting it to heat up the series resistor at 5 watts might be a challenge, but it can be done. Otherwise, it's a current transfomer, ferrite core, diode detector, and 50ua meter. http://www.w1tag.com/RFA.htm A simple diode detector may be enough, but if necessary I'll have to line up ferrite core and get complicated. I'm a master of procrastination I have a PHD in procrastination. Never do today what you get someone else to do for you tomorrow. I was always good at procrastination however I did not consider the part of having someone else do the work -- that's probably why you have the PhD and I don't!! Is that a lot, I ask? Yes, if you try to do it all at once. No, if you take your time, grind the numbers, do a little planning, and invite all your friends to help. That's the nice thing about being a retired senior -- I can take all the time I want, and as you've seen in this thread, I'm doing a lot of planning, and if necessary there I've got lots of ham chums who will be anxious to lend a hand just to get in here and see what I'm up to. Thanks on the tips re the MFJ diodes. I'm aware of them and can test and change them if need be. I have the W8JI procedure tucked away in a safe place on my computer where I may never find it again, Thank heaven for good search tools. I could only test the diodes after they were removed. The 50 ohm resistors in the circuit prevented easy checking with an ohms guesser. I never considered that -- oh well, it should only take a jiffy to pop the diodes out although there is always Murphy to take into account. So far, so good! I guess it wouldn't hurt to have some on hand -- it's pretty inevitable that with the experimentation etc, that I'll be doing some or all will get blown before you can say poof! Yep. My experience is that certain users tend to blow up diodes no matter what they do, while others don't have any problems. I'm sure it's the user, not the analyzer. Possibly static build-up or ungrounded antennas. Dunno. I've been fairly lucky replacing all 4 diodes without needed to calibrate the device. However, if you find the readings off after replacement, see: http://www.w8ji.com/mfj-259b_calibration.htm The procedure took me 2 full days on an MFJ-269B. It went much quicker after I read and followed the instructions. Now there's a very unhamlike suggestion -- wouldn't stopping to read and follow the instructions severely slow down the calibration procedure? Do you think that if I were to ask the management here If I could have an aluminum ladder outside my second floor window -- just to easy my mind about the dangers of fire, they might agree? No. Someone will probably try to steal the ladder. 20ft ladders are not cheap. I ran two u-bolts through the ladder base, and permanently attached the u-bolts to two foundation blocks with half a bag of concrete mix in the hole. Various attempts were made to steal it, but nobody got very far with 30 kg of buried excess weight attached. The connecting antenna wire also acts as a capacitive alarm when the HF radio is not being used. All this was only possible because each condo had its own private back yard. I've considered all the security precautions you took with the ladder. At the moment I'm considering how to rotate it, and wondering if I couldn't use a wooden ladder with lots of wire stapled to it in a multiband Hentenna configuration! I guess I may have to rethink it and take it one step at a time! Now, I have to consider which rotor. Do you by chance know offhand the wind load of a 20 ft Al ladder? How about a folding ladder for the sake of extra length? Another problem with a 2nd floor ladder is that you will be feeding the ladder from the top, rather than from the bottom. That will possibly work, but probably not as good as feeding the ladder from the bottom. I'll use double sideband so that it won't matter which end of the ladder I feed it from! Cheers, this is fun! Irv VE6BP |
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