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  • #16
    reception may be an issue here, lots of deep valleys and high ground.
    I could end up talking to myself!(nothing new there then!)
    Last edited by grumpygremlin; 07-01-2018, 07:43 AM.

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    • #17
      Originally posted by grumpygremlin View Post
      reception may be an issue here, lots of deep valleys and high ground.
      I could end up talking to myself!(nothing new there then!)
      Then move to longer wave lengths like 10 meters which will bounce off the ionosphere. While deep valleys and mountains are always a problem for radio, the lower the frequency, the less of an issue obstacles become.. although other issues do arise.

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      • #18
        Originally posted by Murphy View Post

        Then move to longer wave lengths like 10 meters which will bounce off the ionosphere. While deep valleys and mountains are always a problem for radio, the lower the frequency, the less of an issue obstacles become.. although other issues do arise.
        Right now we are at the bottom of cycle 24 which means frequencies higher than 20 meters are almost useless. But there are short periods of time where you can transmit long distances but be ready to make your QSO's short.

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        • #19
          sorry, i'm not technically minded, all this is over my head.

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          • #20
            Originally posted by grumpygremlin View Post
            i'm only interested in post SHTF, prior to that I have no interest in radios or communications whatsoever, post SHTF I don't understand the need for communication-who are we supposed to be communicating with? might be better to hunker down and keep quiet. I have 2 radios , one mains and one wind up for monitoring any broadcasts, but actually broadcasting myself? no way.
            the Nazi's were good at triangulating radio comms in WW2 and I am sure things have improved on that in the last 70 years.
            I also would limit my comms to listening mostly. BUT don't wait until the SHTF to pull out the radio and wonder how to get it working. Get to know your stuff very intimately before you have a situation. If you want to wait until a event then pull out the batteries and put your stuff in a faraday cage.

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            • #21
              Originally posted by Defcon09 View Post

              I also would limit my comms to listening mostly. BUT don't wait until the SHTF to pull out the radio and wonder how to get it working. Get to know your stuff very intimately before you have a situation. If you want to wait until a event then pull out the batteries and put your stuff in a faraday cage.
              That's what I did.. Pulled the batteries and put everything in the Faraday cage.. including the batteries in case they have protection circuits inside them.
              I also purchased AAA and AA adapters for any devices which run on their own brand of NiMH or Lithium battery. For instance, my Yaesu FT60R comes with a molded NiMH battery that clips onto the back of the unit.. But they also sell an adapter that allows the use of 6 AA batteries.. so I have both. if the NiMH ever goes bad, I can switch over to rechargeable AA's... might not last as long but it would still work.

              The other thing is that a lot of battery units come with power adapter ports where you can plug in a DC adapter from a wall outlet. I pay attention to those too because I can adapt 18650 batteries to run one of those as well.

              Something else I have is called an SDR Dongle.. The cool thing about this device is that if anyone around me is communicating on any frequency, it will show it.. even if I'm not listening to that particular frequency at the time, I'll see the spike in power output on that band..

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              • #22
                Originally posted by Murphy View Post

                That's what I did.. Pulled the batteries and put everything in the Faraday cage.. including the batteries in case they have protection circuits inside them.
                I also purchased AAA and AA adapters for any devices which run on their own brand of NiMH or Lithium battery. For instance, my Yaesu FT60R comes with a molded NiMH battery that clips onto the back of the unit.. But they also sell an adapter that allows the use of 6 AA batteries.. so I have both. if the NiMH ever goes bad, I can switch over to rechargeable AA's... might not last as long but it would still work.

                The other thing is that a lot of battery units come with power adapter ports where you can plug in a DC adapter from a wall outlet. I pay attention to those too because I can adapt 18650 batteries to run one of those as well.

                Something else I have is called an SDR Dongle.. The cool thing about this device is that if anyone around me is communicating on any frequency, it will show it.. even if I'm not listening to that particular frequency at the time, I'll see the spike in power output on that band..
                Good move. I also have a AA case for my older Icom V8 and a solar charger that charges 4 batteries of any size. Does a good job and even puts out enough power to run my small AM/FM radio.

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                • #23

                  Here is some real world testing that we just did this past week..

                  Using just 2 hand held radios with only 5 watts of power, set to 145.xxx Mhz, we were able to communicate out to 7.5 miles through farm and forest... The radio I carried was using a 1/4 wave telescoping antenna with probably 2db of gain.. The radio at the home however, was connected to a SlimJim antenna ($22) that was strung 20 feet up into a tree. (A slim jim is an antenna that rolls up like a short extension cord and weighs about 6 ounces)
                  I live in a semi rural area with cows and corn and thick forest everywhere.

                  I was 7.5 miles out before my signal became too weak for the home base to hear me on their hand held. Interestingly, I could still hear home base transmitting pretty well.. Their slim jim stung up in a tree had a gain of about 6 db with an angle or radiation of only around 10 degrees whereas my little 18 inch 1/4 wave antenna only has about a 2 db gain and its radiation pattern is probably all screwy.

                  We do need to transmit further than 7.5 miles so our next test will be to raise the antenna's up further. When it comes to VHF transmission, the rule is elevation, elevation, elevation.. I built an antenna launcher from a sling shot and a fishing reel and can send a wire over a 100 foot tree fairly easily.

                  I've been concerned with an EMP hitting when my wife is at work 15 miles away.. and because of that, we are setting up a system to communicate if all else fails.
                  Our next test will be with 2 mobile radios pushing 50 watts (Yaesu FT2900's running on 18650 batteries) with the antenna's strung up 40 feet into the trees.

                  If that should fail, then the next step is to go to an 80 meter HF band and use an NVIS (Near Vertical Incidence Skywave) antenna to direct an HF signal straight up into the F layer of the ionosphere and have the cone come down and cover everything for 30 to 100 miles.
                  The problem with NVIS antenna's is that they take some time to set up and are not portable. The 2nd problems is that portable (back pack) HF radios capable of 80 meter transmissions are not cheap.

                  There is one other option I might explore, and that is morse code transmission. I have a system hooked up to my ICOM 746 that lets me use a computer, type in a text message, and the software converts the message to morse code and transmits it.. When the reply comes back, the software decodes the morse code and displays the message.. They even have apps that can do this on an iphone, android, or any tablet.

                  Even better, for about $150 or less, you can buy a single band hf radio designed to transmit ONLY morse code (called CW) on the HF bands.. They are very small at around 2 x 4 x 3 inches and draw very little power. There's an entire hobby built around this kind of stuff where these guys climb up mountains and try to talk to the other side of the world on 5 watts and a box the size of a pack of cigarettes.

                  But my advice for the OP is to stick to VHF and find a way to get your home base antenna as high as you can get it..

                  There's also a formula to figure out how a VHF signal will propagate over the curvature of the earth, and I'll warn you, its a bit disturbing how intrusive our big round ball is when it comes to line-of-sight signals.

                  The formula is as follows:
                  Measure the antenna height in METERS (above ground) and then take the square root of that and multiply it by 3.57 and that's how many KILOMETERS your signal will travel before the curvature of the earth blocks it.

                  If the receiver's antenna is also elevated, you can use the same formula for them and ADD their distance to your distance. This assumes a flat surface like the ocean..



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                  • #24
                    Originally posted by grumpygremlin View Post
                    reception may be an issue here, lots of deep valleys and high ground.
                    I could end up talking to myself!(nothing new there then!)
                    If you're in a valley and need to communicate to the other side of the mountain, your only option is to use MF or HF (around 80 meter band) and an NVIS antenna.. The signal will be directed straight up into the sky almost totally vertically.. when it hits the F layer in the ionosphere, it will bounce back just like a billiards ball on a pool table.. If you get it right, it will go up and right over the mountain and come down on the other side.
                    An NVIS antenna is just a horizontal copper wire about 5 to 8 feet of the ground and cut to the appropriate length for the frequency. Another wire (set of wires) are laid directly on the ground or buried just under the soil to act as reflectors.. they send the signal straight up but the reflectors are not connected to anything.

                    You can build an NVIS antenna for about $30 or less.. only problem is that for 80 meters, they get kind of long..

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