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  • brandon lind's Avatar
    Today, 01:38
    ....and my final proof to this fact is obvious. When you shoot a square TDR pulse down a coax with a mismatched termination, do you see one step or a set of stairs rising with each successive reflection? You see one step. It's a controversial topic but with that, I'll leave it alone now.
    6 replies | 107 view(s)
  • brandon lind's Avatar
    Yesterday, 20:39
    Let me be more specific so nobody is confused as to who and what I am talking about. Tempstar: Your answer is so vague Id call it completely useless. R2D2: Stop sending people off to other peoples work. Ive done that to, but to reputable sources. That website looks like it involved just as much effort in building as his effort in research. K7MEM and R2D2: the theory that a tuner takes advantage of a mismatch to reflect power back and forth till its all absorbed in the coax and/or antenna is complete nonsense. That link takes a combination of factual plagiarism and misunderstanding and mixes it up into a load of confusing garbage. Consider how a quarter wavelength stub that has its end shorted at the far end appears as an open circuit at its input. Now, consider what happens if you remove that short so the end of the stub is open ~ suddenly the input appears as a short circuit. Simply changing what is at the end shifted the input inpedance from a dead short to an infinite impedance, and to you...
    6 replies | 107 view(s)
  • jhodgski's Avatar
    Yesterday, 18:52
    Hiya Martin, Thanks for the reply, but the manual only mentions jumpers K-1 to K-7. The only mention of K8 is in the parts list. Cheers, James
    2 replies | 152 view(s)
  • K6CPO's Avatar
    Yesterday, 17:45
    Most repeaters, linked or not, are open to all licensed amateurs. It's just a matter of courtesy that you wait your turn for a repeater, unless, of course, it's a life and death emergency. I'm unaware what the link frequencies are for that system. I'm not sure what you're trying to accomplish with your example. You mention "co-worker" so I assume you are both in the same general locale. One repeater with the proper placement would allow the two of you to converse with each other. And it really doesn't matter if it's yours, his or someone else's. Even if the repeaters are in separate cities (per your example) linking as I described in my previous post is how to accomplish that.
    11 replies | 233 view(s)
  • brandon lind's Avatar
    Yesterday, 15:08
    If a wise man knows anything, its that he knows nothing at all. If you have never used a smith chart, performed a calculation using complex numbers, or have never heard of hyperbolic trig functions, you have no business answering these types of questions. Sharing your misunderstanding of a topic is what propagates stupidity. If there is a mismatch at the antenna, the coax will TRANSFORM the impedance to something else at the input end of the coax. If you introduce a combination of reactive components (like using a tuner) such that the 50ohm resistive at the radio becomes whatever is at the coax input, the coax will transform it to what the antenna really needs. This, in mathematical terms, is called complex conjugate matching and it occurs in steps as the signal travels through the various system components (tuner, coax, any other matching devices). What is impedance folks??? It is a ratio of voltage to current. Manipulating the phase relationship between the two by using a tuner changes the impedance....
    6 replies | 107 view(s)
  • k7mem's Avatar
    Yesterday, 13:57
    It is a little more complicated than just being lost as heat. But you are correct, in that, the tuner doesn't fix a mismatch. It only allows the transmitter to see a good match. The high SWR causes much of the power reflected back to the antenna tuner. But at the tuner, there is also a mismatch and some of that reflected power is reflected back to the antenna. This happens over and over, until there isn't anything left. And, of course, some of the power is simply lost as heat in the coax. On my web page on UHF/VHF Antennas there is a small calculator for calculating the Loss Due To SWR. The equations for this calculation are also listed. So, in your scenario of 100 watts (at 146 MHZ), assume that you are feeding the antenna with 100 feet LMR-400 coax. The amount of power that will be radiated would be 35.272 Watts. The rest of that power is lost to heat, due to the resistance in the coax. If you instead had 50 feet of same coax, you would be radiating 52.926 Watts. So about half of your power would...
    6 replies | 107 view(s)
  • R2D2's Avatar
    Yesterday, 13:40
    http://www.wc7i.com/reflection%20section.htm?fbclid=IwAR2NSQQCOLnJXNkXwwBQL6wluhEDJZSSMLTs11CLSJSVY7sTYWXeYP2vTk8
    6 replies | 107 view(s)
  • Tempstar's Avatar
    Yesterday, 12:44
    You're on the right track. The tuner presents 50-52 ohms to the final output stage of the radio to make it happy and prevent reflected power from heating the finals to the point of destruction. Since energy in = energy out, the wattage that cannot be absorbed by the antenna and feed line system is lost as heat.
    6 replies | 107 view(s)
  • G7NFP's Avatar
    Yesterday, 12:17
    G7NFP replied to a thread Pre-Noob in Introduce yourself
    https://learntechnique.com/what-is-pat-testing/?ppc_keyword=&gclid=CjwKCAjw2a32BRBXEiwAUcugiJMFTewwaUxuBOU4qDsYetdqm3MJdbUkjrQBy3B7WrwJniZh_8NAXRoCCMcQAvD_BwE No doubt there is an American equivalent. All electrical appliances in "every" business must be tested every year. Companies usually have a tester come in once a year, test everything. IE: every PC, in fact anything that plugs in, right down to the tea break kettle. But they usually have a couple of their employees qualified to do that testing for the odd items purchased in between the annual testing. So having that certificate is a ++ to any employer. When l was in electronics, one of my mates mentioned to someone what my previous career was. (Registered nurse). That news went round like wildfire. So when guys sustained injuries they would come to me as they wanted their injury assessed by a registered nurse rather than a first aider. That pissed off the company. Therefore their solution was to send me on a course for a week to qualify as an...
    15 replies | 236 view(s)
  • dnwiebe's Avatar
    Yesterday, 01:47
    dnwiebe replied to a thread Pre-Noob in Introduce yourself
    Yeah, but I'll bet it's not all crap. I'm probably too ignorant at the moment to reliably distinguish crap from not-crap, but hopefully I won't always be, so I'll save it up and go through it then. And anyway, at least on this board I have no reputation to defend. But in my life I've known enough crotchety old geezers (and as a matter of fact am well on my way to becoming one myself) to understand that the crotchety isn't usually personal. Here's a story about me. I'm an old software developer with very particular ideas about how software should and shouldn't be written. You know those nickel-plated spades that politicians use to break ground in front of the cameras on new construction projects? The ones that are engraved with something and hung on the wall in glass cases? I found a place once that made those. Well, they didn't make them, but they bought normal spades and nickel-plated them and engraved them to order. So at one of my jobs I bought five of those, and had them engraved with what I...
    15 replies | 236 view(s)
  • dnwiebe's Avatar
    Yesterday, 00:42
    Suppose you have a 100W transmitter. You hook up a homemade antenna to it and try transmitting. The transmitter’s onboard SWR meter shows 10:1 SWR and the power amp is automatically rolled back to a watt or two to protect the output stage. You say, “No problem; I’ll just grab my handy-dandy antenna tuner here.” So you insert the tuner, plus an outboard SWR meter, and tune until the radio’s SWR says 1:1. Now your transmitter is pumping the whole 100W and everything looks happy...but the outboard SWR is still showing 10:1. That means 1/11 of your power is being radiated and the other 10/11 is being reflected, right? The tuner doesn’t actually make the bad antenna better, it just makes it look better to the transmitter. Or so I’ve read; I have no experience of my own.
    6 replies | 107 view(s)
  • tngw1500se's Avatar
    Sun 24th May 2020, 21:34
    tngw1500se replied to a thread What to buy? in Amateur Radios
    removed today
    14 replies | 314 view(s)
  • dnwiebe's Avatar
    Sun 24th May 2020, 20:47
    Okay, that's something I didn't know. Separate repeaters that all broadcast the same signal at once. On the one hand, that would make it really handy if you were the guy using the repeater; on the other hand, it would make it really annoying if somebody else was using the repeater and you had traffic waiting for it. Curiosity: the UHF links between the repeaters: are they on amateur frequencies or commercial frequencies? Of course, if my repeater and my coworker's repeater aren't in the same network, we'd still have to bodge together something like my example, yes? Thanks, Dan
    11 replies | 233 view(s)
  • dnwiebe's Avatar
    Sun 24th May 2020, 20:18
    dnwiebe replied to a thread Pre-Noob in Introduce yourself
    It's never occurred to me that a ham license might be professionally beneficial to me. Interesting. I can't see how it could be at the moment, but perhaps there are additional careers in the offing for me the way there were for you. If so, who can say? I used to be a CBer...I think I probably still have a transceiver and antenna in my truck somewhere. It's not mounted or connected, but some years ago I convinced myself that it was a good idea to have one in there for emergencies. Nowadays I have a cell phone, but I've never gotten around to taking the CB out of my emergency kit. Well, so far I have a nine-inch rubber-duck antenna and something between thirty milliwatts and five watts of transmit power. I haven't even been able to hear the bowel-discussers yet. (I heard what I'm pretty sure was some digital traffic on a local repeater--sounded a lot like a telephone modem--but that's the only amateur traffic I've heard yet.)
    15 replies | 236 view(s)
  • G7NFP's Avatar
    Sun 24th May 2020, 20:17
    G7NFP replied to a thread Pre-Noob in Introduce yourself
    And...ROFLMAO I just noticed that you stood up to the old f**t. He tends to spin a load of crap to all the new guys who post in this section. Must admit l got a little annoyed when he decided to criticise me. See the thread in this section "So green l'm still a seed". He gives a lot of advice on that thread that l am sure will be of great help to you.... ;-)
    15 replies | 236 view(s)
  • K6CPO's Avatar
    Sun 24th May 2020, 20:15
    What you're proposing has already been done. I think your example makes it more complicated than it really is. In Southern California, there is a system of repeaters linked via a UHF radio link that connects four repeaters, two in California and two in Arizona. It's called the CALZONA link and is a joint collaboration between the East County repeater Association in San Diego and the Arizona Repeater Association. Anything that goes into one repeater comes out on the other three simultaneously without regard to offsets or frequencies. Four separate operators could hold a conversation, one on each repeater with no difficulty. There is also the WinSystem, a bunch of linked repeaters spanning the better part of the West Coast, California to Washington state. Most of these are linked via the internet, but the concept is the same as using a radio link.
    11 replies | 233 view(s)
  • K6CPO's Avatar
    Sun 24th May 2020, 19:42
    K6CPO replied to a thread What to buy? in Amateur Radios
    Maybe so, but there is nothing you can do about it. It's codified in Federal Regulations. It's simple... If you want an amateur radio license, you have to take the test. Period. Your reasoning is why there are radio services that don't require examinations (GMRS) or even physical licenses (FRS, MURS or CB.) The latter three are "licensed by rule" meaning that as long as you follow the regulations governing those service, you can use them without a license. The trade off is that there are more restrictions on things like radio types, power limits and channels available. You've been offered some choices about what's available to you. You just have to choose which way you're going to go. Further whining about it isn't going to change anything.
    14 replies | 314 view(s)
  • tngw1500se's Avatar
    Sun 24th May 2020, 16:29
    tngw1500se replied to a thread What to buy? in Amateur Radios
    Not everyone who drives a car changes the cam and I'll bet that most ham operators never replace a transistor or a green wire or a fuse for that matter. Radios today require a microscope to work on. How many ham operators even own a soldering gun? Nikola Tesla couldn't repair one. The purpose of a radio is communication. These questions are unnecessarily discriminating against persons who lack technical knowledge. Sure there's a few hams that tinker with radios and antennas but I'd say most install a radio, antenna and just use it after that. Hams call it a "hobby". Some people would just use a radio to talk to others on. Knowing what a green wire is doesn't make for a better radio "operator". I can rewire my whole house. My wife can't but she turns on the bathroom fan all by herself. It's amazing.
    14 replies | 314 view(s)
  • G7NFP's Avatar
    Sun 24th May 2020, 13:06
    G7NFP replied to a thread Pre-Noob in Introduce yourself
    One thing to mention about cheating Dan. When l sat the fork lift truck test. There was a practical + a written exam. The examiner on the written exam went the full mile when checking everyone's identity documents. I later discovered why. An examiner who moved to another test centre recognised a guy from his previous test centre. He wondered why he was back to sit the same test as he passed the month before. He then discovered that his name was different. Turned out that he had sat many of those exams in many test centres under many names. He was charging people a fee for sitting the written test for them. That was 11yrs ago. But no doubt that it still happens. I have no idea how they confirm identity on the online exam. It can't be as easy as holding up a photo driving license as very easy to doctor a document that only needs to be shown to a web cam. But the cheaters will be a tiny minority. But l don't doubt that some guys have given it some thought. I remember years ago (before there was a...
    15 replies | 236 view(s)
  • G7NFP's Avatar
    Sun 24th May 2020, 12:08
    G7NFP replied to a thread Pre-Noob in Introduce yourself
    Interesting that you ask as l just mentioned that on another forum today. Ham qualifications these days are only good if you want to be a ham. Although that was the only thing on my mind when l sat mine 30yrs ago. But back then, the RAE (Radio Amateurs Exam) consisted of 2 exams. The 2nd one (the really hard one that many failed) was a City & Guilds in electronic theory. Which is a professional qualification that allowed me to change career & work in the electronics industry. So having that qualification earned me many thousands. I only realised that when l moved to a new area & took a temp job in a factory until l found work in my own field. Then l got talking to the engineers & discovered they had the same certificate as l did :-) So my next thought was ££££$$$$ Many of my mates who took the exam done it to stop the authorities raiding their house & confiscating all their gear as they were using 11m ssb. (Not saying that l was on 11m ssb :-). So the knowledge l gained was a big win for me. Not...
    15 replies | 236 view(s)
  • dnwiebe's Avatar
    Sun 24th May 2020, 02:47
    dnwiebe replied to a thread Pre-Noob in Introduce yourself
    Sometimes it's an attractive challenge to figure out how to cheat the situation, I'll admit...but I haven't the faintest interest in cheating the ham tests. As I said somewhere else, I really enjoy learning challenging things, and--especially since this has already opened the gate to something else I've been trying to learn for years--I'm looking forward to learning this. So how about you? What's your favorite thing about amateur radio, and why do you like it? What do you hate about amateur radio? What didn't you know when you started out that you wish somebody had told you or showed you?
    15 replies | 236 view(s)
  • G7NFP's Avatar
    Sun 24th May 2020, 02:07
    G7NFP replied to a thread Pre-Noob in Introduce yourself
    To be honest Dan. If it was me..... I would take the exam as l did 30yrs ago. Yes these remote exams are good for people that can't make it to a centre for various reasons. But for me, far too much hassle. Then there is a tiny minority that will look down on those who done their exams online. Me? I would consider those who sat the exam online to have had much more hassle to sit the exact same exam as those who sat it in person. BTW, the problem some guys have is "the potential to cheat". But l just don't see guys even thinking about cheating.
    15 replies | 236 view(s)
  • dnwiebe's Avatar
    Sun 24th May 2020, 00:34
    Aw, c'mon, let him go. I think it's cute when he does the grumpy-old-ham thing. Anyway, I'll bet he's got a fair amount of good experience to share. Why am I in such a good mood? Because I needed a haircut badly, and was just about to go get one after putting it off for way too long, when the Plague struck and all the barber places closed. And today, I finally got my haircut! I feel ten pounds lighter. It'd put anybody in a good mood.
    11 replies | 233 view(s)
  • NicolaJayne's Avatar
    Sat 23rd May 2020, 23:42
    you are the problem, not part of the solution
    11 replies | 233 view(s)
  • K6CPO's Avatar
    Sat 23rd May 2020, 21:48
    K6CPO replied to a thread What to buy? in Amateur Radios
    Your answer leads me to believe you really don't know what amateur radio is really all about. It isn't just for communicating, but also experimentation. That's why the electrical questions. You're going to have to make a choice. To get most of what you want, you may have to sacrifice something else. If the repeater is of prime importance, then you're both going to have to be licensed, If getting your wife licensed is a problem, then you might have to go with GMRS.
    14 replies | 314 view(s)
  • k7mem's Avatar
    Sat 23rd May 2020, 13:21
    k7mem replied to a thread What to buy? in Amateur Radios
    I just ignore R2D2. He just seems to read whatever he wants and then writes a long rant, that no one really reads. Yea, like I said before, you and your wife probably don't want ham radio. But there are reasons for those questions. Ham radio is not just about talking to each other on handy talkies. You can do that with a CB radio and no license is required. IMHO, when you take a ham license test, you are not just getting a license. You gain the right to use a radio on specific bands throughout the HF, VHF, and UHF areas. You can then communicate with other ham operators all around the world. You also gain the right to experiment with your equipment. For example, as a licensed ham, you might want to run all your equipment off of a Solar System. For that, you need to know something about storage batteries. The other questions serve similar purposes.
    14 replies | 314 view(s)
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