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  • paulears's Avatar
    Today, 11:00
    An old battle scarred veteran of UK electric smiled at me when I asked him about grounds for lightning protection. He spent most of his life working for the BBC on new installs and in later life shifted to working for the Government on emergency service towers and installations. He asked me what I wanted the ground for? I was a bit confused. He then explained that what was needed in many cases was a way to prevent static build up on the tower, so grounding it with very light cable would do that nicely. This lowers the noise figures in the electronics and removes lots of fizzy interference. For systems where additional protection was required, then flash-over plasma devices in the coax feeds did quite nicely to protect the equipment. Protection against an actual strike was often futile. Destruction of the input stages of the equipment, and often the entire RF cabin was common, and often, the static protection links acted like fuses, breaking their bond to the tower, but unfortunately doing it after the kit...
    10 replies | 349 view(s)
  • brandon lind's Avatar
    Today, 03:08
    I've always wondered about the glass jar thing myself, it makes no sense using a glass jar to me either. Anyone with a strong knowledge of electricity should know that electricity follows the path of least resistance. That might be from 1) a coax center conductor through a lightning arrestor to ground, 2) from the center conductor to a coax shield (that was grounded) making a half inch jump (assuming a radio don't complete the path), or 3) from an un-grounded coax shield (that is routed nowhere near ground, stupidly), out from the jar that one thinks is a "safety precaution", and to the grounded outlet screw as it crosses the bed where you sleep. The glass jar only adds a few meaningless inches of air if the energy from an un-grounded coax shield were to seek dissipation at the nearest grounding point. Safety to radio and safety to life are two different things, but I see a glass jar doing nothing in either case. Most of what is said about lightning is either based on speculation, or misunderstood...
    10 replies | 349 view(s)
  • K7KBN's Avatar
    Today, 00:30
    Glass IS an insulator. So is air. So seeing lightning bolts hundreds or thousands of feet long through the air, searching for "ground" or a point close enough to "ground" so it can arc across doesn't change the properties of glass. If lightning strikes the far end of that coax you put in that jar, it'll find ground, and all that energy will be dissipated as light, heat, sound and molten glass.
    10 replies | 349 view(s)
  • brandon lind's Avatar
    Yesterday, 21:50
    Unless you are following them with a spectrum analyzer when they key up, there's no way to know exactly what frequency they are operating on. You may be able to make a guess as to the band of operation, but even that is not accurate. The reality is, there is no magic length for a particular frequency. It is very common to see 1/4 wavelength and 5/8 wavelength antennas on vehicles, but that does not mean those lengths are the only ones that work. As long as you can efficiently transfer power to the antenna with minimal reflection, you are on the air. Quarter wave antennas are common because at N/4 where N is any odd integer, the antenna has no reactive component. Typically, with any vertical above 3/4 wavelength, there will begin to be nulls in the elevation plane of the radiated field. For this reason, and for wind loading limitations, N is usually never over 3 for mobile setups. The reason we avoid antennas with N being even is because the reactive component of the input impedance is infinite, which...
    1 replies | 136 view(s)
  • Rhombic's Avatar
    Yesterday, 20:07
    While driving on the continent (especially in Germany), you see cars and vans with whip aerials attached to the roof by magnetic mounts. The vehicles often bear Polish or Romanian registrations. The aerials don't look like the old 11m CB ones that I remember. Perhaps modern CB aerials are different but, if not, what frequencies are they operating on? R
    1 replies | 136 view(s)
  • OldTube's Avatar
    Yesterday, 17:43
    OldTube replied to a thread Vertex 150 Charger in Yaesu
    Thanks! I will check into that. Regards, Don
    2 replies | 134 view(s)
  • brandon lind's Avatar
    Yesterday, 16:27
    I am making an assumption based on your call sign, KD9LSZ.... In Wisconsin, pretty much anywhere in the whole state, you should ALWAYS be in range of at least one 2m repeater (probably several). If you equip your vehicle with a 25w mobile rig, a repeater book and install a decent 5/8" vertical, you should NEVER have trouble reaching someone. As for attempting to use a ham radio outside the ham bands, there's just two things that matter... 47 CFR 97.403 "Safety of Life and Protection of Property" and 47 CFR 97.405 "Station in Distress". As you HAVE an amateur license, you have the privilege of using ANY MEANS at your disposal to get help (assuming a real emergency). Even if that means putting a ham radio on GMRS or a police repeater! If you abuse that privilege, your license will disappear and the FCC will crawl deep up y.... In the extremely unlikely event that such a situation should happen with no 2m repeaters in range, you would likely be looking for an "open" radio like the Baofeng UV-5RV2+, a...
    4 replies | 274 view(s)
  • paulears's Avatar
    Yesterday, 14:15
    I wonder slightly differently. There seems to be an expectation that worldwide, there is some kind of 'emergency' radio system, when the reality is - there isn't! Most of the emergency services are going digital and many, like all in the UK, encrypted - and the very last thing any they want are people popping up in an emergency. If people want to be able to access other people's systems and networks, they need to be coordinated. If you have a transceiver that can operate anywhere - who exactly would you be talking to? The systems just don't cater for this kind of approach any longer - practically or legally. People cite the fact that in many jurisdictions you can use any radio available to you where there could be genuine loss of life - but technology nowadays means this gets less practical every month as the user base migrates to systems resilient to interference and interception, which is how they consider random access by non-approved users. It also gets embarrassingly non-emergency. People who have...
    4 replies | 274 view(s)
  • Obed's Avatar
    Yesterday, 12:20
    glass is supposed to be an insulator. Years ago I brought all my coax runs to one board on the back of my bench. I used thru the wall coax connectors and drilled holes in jar lids and put them on the connectors... in storms I would drop the jumpers from my rigs and screw jars onto the lids....never had the misfortune of seeing if they helped or not...an effort I am glad never paid off....or failed.
    10 replies | 349 view(s)
  • WZ7U's Avatar
    Yesterday, 01:55
    WZ7U replied to a thread Land Mobile Radio? in Mobile Operating
    There is no "One Knob To Rule Them All" and I'm not sure where this notion comes from, but I see it with more regularity on many forums. The only way to get even remotely close is to have the proper licensing and separate radios/antennas for all the different services, which is impractical at best. Choose to get your General and work with HF on 40 meters which in a typical mobile install will easily get you out within a few hundred miles NVIS (Near Vertical Incident Skywave - google it) which will be way more distance reliable than a GMRS rig will be. A cell phone is a radio too, about as distance reliable as a UHF radio is. Besides, why are you venturing into the "forest" without a friend in another rig to be backup? I live in a forest and never go anywhere alone, because where I go it wouldn't be prudent to be alone should something go horribly wrong mechanically or medically. Common sense will get you out of more scrapes than a radio will.... Have a fun, safe trip and look over this website for...
    4 replies | 274 view(s)
  • WZ7U's Avatar
    Yesterday, 01:41
    What exactly is a glass jar supposed to do with lightning? Become shard material when it explodes? :confused-new:
    10 replies | 349 view(s)
  • WZ7U's Avatar
    Yesterday, 01:33
    Congratulations as well as condolences. Welcome to the ham radio thing we all love. A very touching story indeed, best of luck and I hope to talk to you someday soon. 73, Eric
    3 replies | 194 view(s)
  • WZ7U's Avatar
    Yesterday, 01:03
    WZ7U replied to a thread Re: hello in Introduce yourself
    For those who may not know, Elmer is slang for mentor.
    2 replies | 80 view(s)
  • brandon lind's Avatar
    Mon 10th Dec 2018, 23:50
    An example of parallel use might be a hairpin or coax stub measurement. The rigexpert website suggests that these analyzers are also useful for component testing. An excerpt from https://www.hioki.com/file/cmw/hdCatalog/4797/pdf/?action=browser&log=1&lang=en states: "Since the impedance measuring instrument is unable to determine the measurement target’s circuit mode, it is necessary to select the correct equivalent circuit mode in order to reduce error. Generally speaking, series equivalent circuit mode is used when measuring low-impedance elements (approximately 100 Ω or less) such as high-capacitance capacitors and low-impedance components, while parallel equivalent circuit mode is used when measuring high-impedance elements (approximately 10 kΩ or greater) such as low-capacitance capacitors and high-impedance components." Information from another source http://www.phys.ufl.edu/~majewski/nqr/paper/nqr_detection_educational/series-parallel-impedance-parameters-an.pdf
    1 replies | 158 view(s)
  • Danny 61's Avatar
    Mon 10th Dec 2018, 23:27
    New Member, Got out of HF for a while, just didn't have time. Currently running a Kenwood TS 440-S with a G5RV about 35' up. Also just purchased an Icom 7300 and MFJ 939-I auto tuner. Should receive them later this week. Hear a lot of good things about this machine. I live in North Mississippi and would like to get to know some more Hams.
    0 replies | 43 view(s)
  • Obed's Avatar
    Mon 10th Dec 2018, 20:55
    Obed replied to a thread Re: hello in Introduce yourself
    welcome to the forum. The best advice I can give someone starting out is to find their local amateur radio club, attend a meeting and let them know your interests. Most clubs are very welcoming to new folks and have guys around who love to elmer.
    2 replies | 80 view(s)
  • Johncampo's Avatar
    Mon 10th Dec 2018, 14:38
    Johncampo started a thread Re: hello in Introduce yourself
    Hello, Im new here and to the amateur radio world. Im currently awaiting for the study material I ordered so I can start studying for the Tech level license. Any advice is greatly appreciated. Thanks, John
    2 replies | 80 view(s)
  • RF-Burn's Avatar
    Mon 10th Dec 2018, 12:25
    RF-Burn replied to a thread 450ohm ladder and coax in Antennas
    Hi Dan31 . After reading your query, and noting the 50 m( approx 163 feet) run to antenna, I would suggest , stay with the 450 ohms feeder line.! and use an antenna tuner , although you do not mention , just what antenna you will be using, straight dipole? multi -band non- resonant top ? etc ! The main small problem , with 450/300/ feeders is the wet weather effect, but personally speaking , I don't find that a great problem.. My own 450 ohm feeder comes thru' the roof space (attic) The small workshop you mention, would obviously be the ideal
    4 replies | 166 view(s)
  • K6CPO's Avatar
    Sun 9th Dec 2018, 23:39
    What about it? It's strictly a 2 meter radio. It doesn't transmit on any other band. The specs vary by market, but it's still designed for amateur use only.
    10 replies | 300 view(s)
  • 5B4AJB's Avatar
    Sun 9th Dec 2018, 21:55
    5B4AJB replied to a thread Vertex 150 Charger in Yaesu
    It's probably time to change those NiCd cells, 15 years is pretty long for Nickel Cadmium. You can calculate it approximately from the supplied charge current & mAh rating of the battery pack. Finding the "C" rating from the manufacturer will tell you the most current you can dump into the cells for charging, usually around 1/10th the output current. - should be around 6 hours...
    2 replies | 134 view(s)
  • OldTube's Avatar
    Sun 9th Dec 2018, 20:36
    OldTube started a thread Vertex 150 Charger in Yaesu
    Does anyone know how long it should take to recharge the Yaesu Vertex 150. The little charger red light stays on for more than a day. I think this model was made around 2003. Thanks, Don
    2 replies | 134 view(s)
  • AC5PS's Avatar
    Sun 9th Dec 2018, 15:22
    What about the Yaesu FT-4VR ?
    10 replies | 300 view(s)
  • VK4CCV's Avatar
    Sat 8th Dec 2018, 06:06
    Hi All, I have recently purchased a new AA-55 Analyser in an effort to improve and better understand my Transmission Line & Antenna combination. I have a number of questions but I will start with this one: In the data screen
    1 replies | 158 view(s)
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