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Connecting radios in car so they are "Portabl
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by KB9RPD on May 17, 2001
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Ok, I'm a bit confused here.
Everyone always says to connect your radio directly to the car battery (in-line fuse on positive lead) running the wires away from car's computer.
But, why would you NOT want to use the cigarette plug? Does it not have enough power or too much, etc.? If you can use the cigarette lighter, what should you avoid or what is recommended?
I'd like to install my radio (not yet purchased) in my car so I can easily take it out of the car for home operation or field day type operation. What kinds of connectors would be good for the wires that come from the battery of the car that I could also use with other power sources for out-of-car use?
Tnx
73, Ted
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RE: Connecting radios in car so they are "Por
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by WB2WIK on May 17, 2001
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For low-power (handie-talkies) or temporary use in a pinch, of course the cigar lighter socket works. There are valid safety reasons for NOT using the cigar lighter outlet for 50-100W or higher powered rigs, and there are valid "noise immunity" reasons for NOT using the cigar lighter connection, for anything other than a cigar lighter:
1. A 50W output VHF rig can draw as much as 12Adc. Under high ambient temperature conditions (automobile, enclosed, sitting in the sun with the windows closed yields ambients of 150 degrees F pretty quickly), the wiring for the cigar lighter outlet is not rated to provide this much current for very long. A cigar lighter heats up and shuts off within 20 seconds; thus, the wiring to it may be overstressed without fear of burning the insulation off the wiring. The same cannot be said of an amateur transmitter. Although the wiring insulation is allegedly "flame retardant," which really means that although it can ignite, it should also self-extinguish, there is no question that many car fires have been caused by wiring defects and short circuits. It's too much of a potential hazard to ignore.
2. Higher-powered radios, such as 100W output HF rigs, can draw 20Adc from the same source and are therefore even a greater potential risk.
3. The wiring to automotive cigar lighter outlets is not routed from the battery directly to those outlets; there are fuse panels and power distribution panels in between, which create additional electrical interfaces and longer wiring than needed, both of which create additional resistance in the wiring path. The cigar lighter couldn't care less if it is supplied with 13.8V or 11.2V, it will get hot, anyway. But your rig does care. Amateur mobile equipment is all designed to operate at 13.8Vdc average, and typically 13.2V min, 14.4V max. Outside this range, it is unknown exactly what will happen, and multiple problems can occur, including reduced transmitter output power (almost guaranteed to occur), modulation distortion, reduced noise immunity, frequency instability, receive audio distortion and a variety of other maladies.
4. It is extremely unlikely that your cigar lighter outlet wiring can support full-power amateur equipment operation and also maintain 13.8Vdc measured at the radio, due to the wiring and interconnect losses detailed in (3) above. Again, for a 3W handie-talkie drawing only 1 Ampere from the outlet, this is probably not a problem. But for a 50W output mobile rig, it does become a problem, quite often.
5. The way to run power wiring for a mobile rig so that it is least likely to introduce noise, hash and whine into your radio, and thus into your transmitted signal, is to use extremely low-resistance wiring in the shortest possible path* from the source of power (your car battery) to the radio itself. Both + and - terminals should be fused to assure absolute protection to your rig in the unlikely event other electrical elements in the vehicle fail, and those fuses should be located right at the battery terminals.
*Note: Shortest and most direct route, avoiding contact with HV wiring (ignition wiring) and extremely hot surfaces (exhaust manifold, etc).
It is very easy to use low-resistance quick-disconnect plugs and receptacles located right near the radio to make it fast and easy to remove and re-install. I recommend using RV/trailer type terminals, which are very high quality, very low resistance, are oil/gas/water resistant material, while still being inexpensive and readily available.
73 de Steve WB2WIK/6
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RE: Connecting radios in car so they are
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Anonymous post on May 17, 2001
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hi,
I have my kenwood 742 in a surplus
laptop case. I mounted it on plexiglass
and it is secured with the velcro from the
case. I use a short bolt and wing nut to keep
the velcro flat and tight in case of a crash
or hard driving.
WHen I leave the car, it goes with me to
prevent theft. For 5 or 10 watt use I use
the power accy. (not lighter) plug.
When I run high power I go direct to the
battery using quick disconnects anderson powerpoles
I got used from a hamfest. I run #10 wire too.
Fused at battery both sides.
73
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RE: Connecting radios in car so they are
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by G8TDU on May 30, 2001
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i,m sorry but after reading your reply i have to say i dont agree with the majority of what you had to say.
what you actually achieved was to scare the pants off someone who had very little experience, and political correctness as you applied had no space in this issue.
whilst some of what you said was fairly correct i'm sorry to say the majority wasnt.
73's g8tdu@aol.com
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RE: Connecting radios in car so they are "Por
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by G8TDU on May 30, 2001
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hi,
ive just read the reply that you received fron wb2wik and i have to disagree with most of what he had to say.
there is a thin line between common sense and political correctness which he applied in his answer,
there are many reasons for his answer but not many that spring to mind at the moment. if you can give me further details of what you want to do i will give you safe common sense replies. i am an electrical / electronics engineer of 44 with many years experience and i have been where you are before...got the book...seen the film...T shirt etc..etc
John McAvoy..... (G8TDU@aol.co)
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RE: Connecting radios in car so they are "Por
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by KL7IPV on May 31, 2001
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John,
You said you disagreed with most of what Steve had to say on this subject. Rather than leave it at that, why don't you say what you believe to be correct and let us all know how to do it correctly. By just saying Steve is wrong based on all YOUR years of experience and not telling us why he is wrong is more scary than Steve telling what he believes to be good advice. By the way, from what I have seen of Steve's answers and what I have learned in over 40 years in the field of electronics and telephone engineering and 35 years of using radios in a mobile situation, I find Steve's answers are generally sound and correct. Please enlighten us if we are wrong. The reason I didn't add to Steve's answer this time was I didn't feel his answer needed explanation nor correction. You're up John, tell us.
73,
Frank
KL7IPV
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RE: Connecting radios in car so they are "Por
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by WB2WIK on June 1, 2001
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G8TDU, by all means, enlighten us!
I had intended my reply not to scare anyone, but just tell it the way it is. I, too, am a graduate electrical engineer (age 49), 35+ years of hamming, and have installed (and unfortunately removed, and re-installed) not just dozens, but probably hundreds of mobile transceivers between 1969 and today.
And most of what I wrote came from the Society of Automative Engineers' (SAE) manuals, some of which are available on line in the form of White Papers, written by knowledgeable experts in their fields.
73!
Steve WB2WIK/6
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RE: Connecting radios in car so they are "Por
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by KB9YNB on June 7, 2001
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As another EE with experience in mobile electronics installation, I would have to say that I agree with Steve and his (overly?) cautious advice. There are several points that he makes that really cannot be debated. AS I SEE IT, those are:
1. Cigar lighters are NOISY power points. They are connected to the battery through the car's fuse panel (an electrical noise party area) and don't have the advantage of a large filter capacitor (read: car battery) to suppress the noise.
2. ANY power accessories that you (or anyone else) add to your car should be fused AT THE POWER SOURCE. Why? you are routing wires through areas that (most of the time) were not designed to carry wire. This means that there MIGHT be sharp edges, un-radiused bends, and excessive tension that the wire has to deal with. If your car remains parked, this really isn't a problem. CARS VIBRATE when you drive them. Even a little vibration, after 50,000 miles, can wear through the insulation of a wire. When that worn spot comes in contact with the car frame or body, IT WILL conduct electricity! If you have fused the wire at the source, it will simply blow the fuse... if you haven't, Congradulations! You have just created your very own welder! If you used small gage wire, it will most likely vaporize the entire apparatus instantly, leaving you with the smell of ozone and melted plastic. If you used large gague wire, you will most likely burn your car to the ground, as the wire will be bouncing around, sparking on every metal surface it touches, until the battery dies, the wire burns up, or both.
Those things being said.... use COMMON SENSE when wiring your radio. Look at the size and length of wire that comes with your radio.... my Yaesu 2600 came with about 10 feet of 12 gauge(I hate that word) wire, with fuses positive and negative at the source. The wire feeding my power point in my Nissan Altima was 18 ga., visibly MUCH smaller than what Yaesu provided. COMMON SENSE would say, I shouldn't connect this to the power point if I plan on using my radio at full power.
I think Steve was right on with his post... people should take CAUTION when installing aftermarket electronics in their vehicle.... it makes the job easier, safer, and more reliable, and it gives good piece of mind while you are using your vehicle and your rig. "Good Amateur Practice," means being safe, and having fun... I think we can all agree to that.
So, to the fellow who wants to install his radio.... BE SAFE, use COMMON SENSE, and HAVE FUN while installing it.
73, KB9YNB
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RE: Connecting radios in car so they are "Por
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by KC8NIC on August 27, 2002
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So all "Steve" needed to say was "Run a nice big juicy fat wire from your car battery to your radio, fuse on both sides, and you'll be all set to go! That's what I find works best and I'm sure others will agree." Instead, he had to try to impress everyone with his vast knowledge of electronics. I bet he's one of those who won't talk to a No-Code tech!
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