Activity Stream

Filter
Sort By Time Show
Recent Recent Popular Popular Anytime Anytime Last 24 Hours Last 24 Hours Last 7 Days Last 7 Days Last 30 Days Last 30 Days All All Photos Photos Forum Forums
  • pmh's Avatar
    Today, 10:44
    pmh replied to a thread High output power supply in The Junk Box
    Computer (switched mode power supplies) are far from ideal for testing audio equipment, and should really be avoided due to noise. My 100/150WW amp head (RMS) has a linear power supply using toroidal transformers, and it is this type of supply you should go for. This is +-55V DC at 2.5A into 8 ohms (100W) and 5A into 4 ohms (150W). This would relate to around 10A and 20A, or so, at +-13.8V. Kind regards, Phil Yes, why would you need so much current to test the audio amplifiers?
    2 replies | 32 view(s)
  • paulears's Avatar
    Today, 10:35
    Thanks for that - cable never really took off here, but the younger people are streaming, and Netflix is pretty popular - satellite tends to be two providers, one paid for (Sky) and Freesat - which tends to mirror our terrestrial channels - We have the shopping channels - quite a few US, but most run evenings, through to 9am. During the day we get the motoring/DIY/Judge Judy/CBS stuff, plus our 5 national channels, and other re-run stuff. Not many religious ones though.
    10 replies | 170 view(s)
  • pmh's Avatar
    Today, 10:25
    pmh replied to a thread What you need to know. in The Junk Box
    There are many legitimate questions somebody new to a hobby/discipline needs to ask. However, I do believe that some of the questions asked by some of the newly passed is because of poor initial training. There is no excuse for disrespect. I have never condoned bad behaviour, and never would. I do, however, think some get frustrated by what they feel are members asking questions without any attempt to research first. Again, is this a result of poor initial trading? After all, you'd be quite disturbed if somebody who had just passed their driving test came and asked you to explain the brake pedal again!
    13 replies | 202 view(s)
  • OH8GAD's Avatar
    Today, 10:03
    OH8GAD replied to a thread What you need to know. in The Junk Box
    So true, being a radio amateur isn't just about learning, it's about teaching and, to me at least, a good teacher helps someone want to learn - When I was at college, way, way back when digital communications meant radios had 7400 and 4000 series chips in, I struggled with the higher maths. Imaginary numbers for god's sake! Back then, my imagination involved improbable beasts and women in chain-mail and lizard-hide bikinis. Numbers had to be real. I also played around with aerial and radio designs. My maths tutor took me aside and asked what was the problem. I just couldn't relate to the likes of imaginary numbers, matrices and so on. When he pointed out that reactance j was just i because I was already dibbsed by current, and several other real-world applications for various other mind-boggling maths thingies, I started getting much better results. I passed. Not spectacularly, but enough. Fast forward a few centuries and one of my boys who just started school was struggling with his homework. I...
    13 replies | 202 view(s)
  • OH8GAD's Avatar
    Today, 09:42
    12 volts should be enough to run any mobile equipment. The reason 13,8 volts gets bandied about is because that is the common charging voltage for a vehicle's battery. If you run your gear from a battery that is not being charged then the voltage will be usually just over 12 volts. Why do you need hundreds of amps, may I ask? Even a 100 watt amplifier will need less than 20 amps at 12 volts - in a perfect world, with 100% efficiency, it would be just over 8 amps, but life ain't perfect ;) To get that high current (100 A plus) with a linear power supply, you would need a really meaty transformer and several high current power transistors, such as the 2N5686, which can handle 50 amps. The design of these power suppliers is pretty simple and all you would have to do is find one and scale up the component ratings and materials to handle such power. I would also add in serious protection such as reverse polarity, variable current limiting and short-circuit protection - I've shorted out a small 12 volt 9...
    2 replies | 32 view(s)
  • Map's Avatar
    Today, 00:32
    Map started a thread 706MKIIG & CT-17 issues in Icom
    I just purchased an Icom CT-17 and hooked it to my 706MKIIG. I can not get HRD to connect to my radio. I suspect either the interface or the radio is faulty. Does anyone know of a way to test whether or not the CT-17 is functioning and actually connected to the radio. Does a software test exist? Thank You Mark KC1GNH
    0 replies | 18 view(s)
  • essbee's Avatar
    Yesterday, 23:30
    essbee replied to a thread What you need to know. in The Junk Box
    In the USA, we study and then test. The first test is for the Technician class license, and I think it's sufficiently detailed to prepare new hams for their restricted privileges. But you guys are trying to deflect the point towards something else. For instance, pmb thinks capital letters in a post are not respectful. But look at the lack of respect shown by the some of the members on this forum that goes unchallenged. Bottom line; offer help or remain silent.
    13 replies | 202 view(s)
  • BEASTBOXES's Avatar
    Yesterday, 17:12
    Hi all, My names Ian im new to the forum, im an avid car audio enthusiast and have stumbled upon the old ways of Ham radio and its power supplies. I have been studying ways to build power supplies for bench testing audio amplifiers, currently using computer server power supplies with 100A and using the 12v rail hooked up to a bank of batteries, unfortuately i guess the difference in voltage potential its a lets face it not the best setup Ideally as you all proably know i want to be able to run between 13.8v - 14.4v so i have been looking up ways and came across building Ham radio supplies. So im here in hope that one of the members here might be able to point me in the right direction to understanding how i would go about building something that would put out over 100 150 even 200A at those higher voltages? Any help would be greatly apreciated, ive read over lots of schematics and i have a general idea of how a supply is built, the general components (transformers, rectifiers, resistors, etc) so...
    2 replies | 32 view(s)
  • pmh's Avatar
    Yesterday, 17:06
    pmh replied to a thread What you need to know. in The Junk Box
    All valid and interesting points, which leads me to ask how you go about getting licensed in the USA? In England, you have to attend a registered centre, usually a club, where you have to undertake a practical assessment signed off by an RSGB registered assessor, before sitting the exam. Questions are not public knowledge. During this time, students usually mix with other club members and also get some on air experience. They also have the opportunity to discuss aerials, equipment, and ask questions, etc. I think this system works very well, and gives some preparation. Kind regards,
    13 replies | 202 view(s)
  • GTGallop's Avatar
    Yesterday, 14:48
    Oh yes! Our digital TV transmissions are all UHF now but the penetration of cable, satellite and other means of "television" mean the OTA Broadcast have largely gone the way of the Dodo Bird. You can still buy these on Amazon but they are starting to get rare. No brick and mortar stores carry them. Personally, we "cut the cord" and abandoned satellite and cable. We watch OTA (over the air) broadcasts and stream over the internet through Amazon and Netflix. My TV antenna is mounted off the south side of the house since all of the TV broadcast in my area come off of one mountain top - no need for a rotor. I put a high gain yagi on that pole and I get about 88 channels of television broadcast. But here is the catch - only about 3 of them are worth anything. Most of it is religious programming (which is great but I'm only one religion not all 12 that they broadcast), or home shopping channels, or Spanish programming which I don't speak. So while there is tremendous potential in the broadcast of...
    10 replies | 170 view(s)
  • GTGallop's Avatar
    Yesterday, 14:34
    Speaking as someone who was once new and green: 1. I found the ARRL books conceptually and contextually out of date. I'm not a paper ham, I studied and read and passed my test on the first shot with a 100% perfect score. But I was ill equipped to start transmitting on the air waves. I was on 70cm Repeaters calling CQ CQ CQ. 2. The internet was an even worse source of information. there is a lot of great info out here but mixed in is a fair amount of misinformation. Not intentionally bad information but not framed in the right context. An operator in the desert on a mountain top will have different experiences than someone deep in Sequoia National Forest. I was drowning in unhelpful information. I think in older times the right answer would have been an Elmer. But with Gen Y, Millennials, and now Gen Z joining our ranks, the concept of an Elmer is fading fast. It doesn't mesh with their learning style. And lets face it - we will all be a silent key one day and these kids will be the old...
    13 replies | 202 view(s)
  • pmh's Avatar
    Yesterday, 13:31
    pmh replied to a thread What you need to know. in The Junk Box
    We are all from different generations, and are used to dealing with issues in differing ways. When I first came here I looked through many of the existing posts, where I often found the answer to my question without having to ask again. Many new comers to a forum, asking a question, may not realise they are the 10th person to ask that question in succession. That's what I think frustrates some forum members. I'm not saying it's right, but understandable. The modern generation do appear to want instant answers, or somebody else to put the effort in.
    13 replies | 202 view(s)
  • Sudden's Avatar
    Yesterday, 13:29
    Sudden replied to a thread What you need to know. in The Junk Box
    It could be thought of as try to find the answer yourself which would give yourself confidence to look deeper and have the satisfaction of knowing 'I sorted that'. I have a handheld which doesn't put out CTCSS tones for some reason. Based upon the responses I have had to questions about it leave me to think I have the only one in this galaxy. I do not consider the 'no' responses as people ignoring me just that they don't know or care. I am still looking for answers to this problem.
    13 replies | 202 view(s)
  • essbee's Avatar
    Yesterday, 11:40
    essbee replied to a thread What you need to know. in The Junk Box
    pmh, you make some very good points. But how can someone appear "lazy" by coming to a community of people with experience to ask questions? Why would anyone search the internet prior to coming here? Some of the fast-finger posters just come across as mad or above learning themselves, although ham radio is a constant learning experience that never ends.
    13 replies | 202 view(s)
  • pmh's Avatar
    Yesterday, 10:57
    pmh replied to a thread What you need to know. in The Junk Box
    Point taken. It is very hard to convey emotion in text, and I don't think many threads are posted to be as harsh as they often sound. Local meanings often vary. That said, we are known as a helpful community, and we should do what we can to assist, otherwise there is no point in being part of a forum. I do appreciate the frustration though. Many new comers do ask question for which a simple google search would provide many simple answers, and it does come across as lazy. That said, newcomers may want to post something, to get involved, and these are the only topics that spring to mind. So, please, let's try and be helpful and, as Marge Simpsons mum once said, "if you haven't got anything good to say about anybody, then it's best to say nothing".
    13 replies | 202 view(s)
  • paulears's Avatar
    Yesterday, 10:46
    Follow up question. I'm assuming it's because US TV frequencies are in different bands, or spread across a wide range that this design exists as a 'buyable' antenna? In the UK, when we had VHF and UHF on the go for a few years circa 1968, we had dual band yagis, with a diplexer both ends, never log-periodic. Did the US run with the wide band approach? History now, as we're totally UHF now, but I'm always intrigued how our two countries did things differently.
    10 replies | 170 view(s)
  • paulears's Avatar
    Yesterday, 10:35
    paulears replied to a thread Twin Lead?? in Antennas
    need a picture really as google has never heard of it?
    3 replies | 135 view(s)
  • K7KBN's Avatar
    Yesterday, 01:58
    K7KBN replied to a thread Twin Lead?? in Antennas
    I thought I'd posted this already, but I searched for Scientific Atlanta and found that they'd been taken over by Cisco. There's a page on the Cisco announcement giving suggestions on where to look for SA parts and stuff.
    3 replies | 135 view(s)
  • essbee's Avatar
    Fri 21st Apr 2017, 23:40
    essbee replied to a thread What you need to know. in The Junk Box
    Obed said it very well. I rarely check into this forum anymore because I can't understand why the condescending members are allowed to continue to post such discouraging stuff. Also, any moderator should be able to see that new members are turning elsewhere, and they should be able to stop this elitist posting. This forum isn't realizing a fraction of it's potential. Welcome every ham, and meet their needs whatever they are. If you can't offer real help, please - don't post and just move along.
    13 replies | 202 view(s)
  • G0NMY's Avatar
    Fri 21st Apr 2017, 22:42
    The 300 Ohm feeder needs to drop down vertically and needs to be as far away from buildings as possible, (free space) as it is part of the antenna.
    2 replies | 130 view(s)
  • pmh's Avatar
    Fri 21st Apr 2017, 21:47
    pmh replied to a thread 'Random' wire in Antennas
    I had a random wire, around 14 metres in length, plugged directly into the back of my MFJ intellituner for some time without an earth and it worked okish. I did eventually take an earth to a ground spike. However, before connecting, I checked the voltage between the spike and the house earth, which was around 5 volts, so I had no concerns over using it. If your house is PME, which is very likely, there are potential hazards in using an external earth, especially if there is a local neutral fault. This is the reason I checked before connecting. One of our club members is just under 50 volts on his, for which the local DNO said wasn't a concern. Kind regards,
    3 replies | 122 view(s)
  • M3EVF's Avatar
    Fri 21st Apr 2017, 09:18
    M3EVF replied to a thread 'Random' wire in Antennas
    Thanks G6KIZ. Thankfully out CH system was fitted when the Ark was at sea :untroubled: and is copper throughout. I have tested continuity between the mains earth and a radiator feed pipe and it's very low resistance...I do appreciate your comment about mains-born noise...esp as we use some IP over mains - although this is on a different ring-main. I'll certainly consider ground radials if the noise is too frightful! Thanks again
    3 replies | 122 view(s)
  • G6KIZ's Avatar
    Fri 21st Apr 2017, 08:37
    G6KIZ replied to a thread 'Random' wire in Antennas
    You can certainly try it although most CH uses plastic piping these days and you will be using the mains earth which will introduce some noise. A good earth is not an easy thing to achieve and you may have to lay ground radials just as you would for a vertical to get best results.
    3 replies | 122 view(s)
  • G6KIZ's Avatar
    Fri 21st Apr 2017, 08:34
    To match well on multiple bands you'll probably need an external tuner as it sounds like the inbuilt one can't cope. What is essentially a dipole at only 15-20ft high is going to be a bit of a cloud warmer anyway. PSK31, WSPR and other digital modes work with very poor signal levels and with a noise level far worse than needed for voice. I think your antenna is probably working as well as it can rather than having some fault other than its inbuilt limitations.
    2 replies | 130 view(s)
  • G6KIZ's Avatar
    Fri 21st Apr 2017, 07:57
    G6KIZ replied to a thread Twin Lead?? in Antennas
    It sounds like the cable which I think is used for FM radio in the USA although that isn't usually totally flat. The stuff I have is made from translucent polythene and you can see the copper inside it at the edges. Some standard ham 300 ohm twinfeed I have is 3/8" wide so I'm guessing what you have is too although the impedance is pretty much irrelevant for making a J pole anyway.
    3 replies | 135 view(s)
  • M3EVF's Avatar
    Fri 21st Apr 2017, 07:42
    M3EVF started a thread 'Random' wire in Antennas
    I'm going to have a go with a random wire (31 feet). As I need a good ground, is it acceptable to use the bonded earth in the house - eg. the central heating pipework that is bonded to earth? Thanks David
    3 replies | 122 view(s)
  • fredb29617's Avatar
    Fri 21st Apr 2017, 01:22
    fredb29617 replied to a thread Base Radios Queston on the TS-480-HX in Kenwood
    You were on the head Pat it was the Rf had to turn it up to 97 but that did it. K4EMP
    2 replies | 53 view(s)
  • K7KBN's Avatar
    Fri 21st Apr 2017, 00:50
    K7KBN replied to a thread Base Radios Queston on the TS-480-HX in Kenwood
    Try turning the RF gain control all the way up. You may need to back off the AF gain ...
    2 replies | 53 view(s)
  • pmh's Avatar
    Thu 20th Apr 2017, 20:45
    pmh replied to a thread 30 Mhz signal in The Junk Box
    I need to point out that this is a ham radio forum, and this question has nothing to do with ham radio. You are also quoting frequencies outside of the (UK) ham radio bands. As Paul has, quite politely and tolerantly put it, we have already tried to help with this matter. Sadly, it is not the members here that do not understand. This thread is now closed and moved to a more appropriate location. Kind regards,
    5 replies | 190 view(s)
More Activity