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Alaskan

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Here's a VHF radio repeater I built into a Pelican case at work, still finishing it though, needs ID and operating instruction plates installed, but they aren't finished yet.

 
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Alaskan

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No clock in it, just on-off and a battery test switch :p This thing will be used by the Alaska Mountain Rescue group when they are out on missions to save peoples lives. What it does is receive radio transmissions and re-transmit them from a high spot, normally this would be put near the top of a mountain in an area they are searching in, or working to help someone.
 

RedCowboy

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Those alkaline batteries have a lot more Mah that most people would think.
I am surprised they don't use satellite phones. Is that because of bad weather?
 
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No clock in it, just on-off and a battery test switch :p This thing will be used by the Alaska Mountain Rescue group when they are out on missions to save peoples lives. What it does is receive radio transmissions and re-transmit them from a high spot, normally this would be put near the top of a mountain in an area they are searching in, or working to help someone.
Good work Alaskan, your work will help save people's lives. Sorry but I can't +rep you again yet. I was once rescued by Snohomish county search and rescue. 18 vehicles and a Snohomish county sheriff's car drove deep into the wilderness on an unpaved road to the trail head, one hiked in and found me while another was on the way, and a little later they radioed for help when I couldn't walk out with them on my own, about 20 more people hiked in when it was getting dark and got me out, including an LPN sent to determine my condition, by that time it was snowing very heavy. This took a few hours. The person that had dropped me off there was waiting to drive me home or to the hospital, but they wanted to call in a medic aid unit to take me to the hospital but I refused. I had no insurance and two previous trips to the emergency room some years before had ruined my life. So I went home, the next day they called the person who drove me home and told them to check on me to be sure I was still alive. I was still alive but had nearly died, never went to the hospital though. What happened was this was in September and I thought I coud get in one more hiking trip, I was going to set a new record for myself and make it 9 days, the trail was about as difficult as they get, there was a place on the way in where I slipped and fell and was injured but I still made it to my destination and camped there for 5 days, then the weather changed, but two days before I met a woman hiker who without me requesting it had gone to Snohomish county search and rescue to report that I was there, she was thinking I may not make it out on my own. When the weather turned bad the person who drove me up there decided to make a 911 call, not knowing anything about what had happened. Anyway I am still here, hopefully for awhile longer.

Alan
 

GSS

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No clock in it, just on-off and a battery test switch :p This thing will be used by the Alaska Mountain Rescue group when they are out on missions to save peoples lives. What it does is receive radio transmissions and re-transmit them from a high spot, normally this would be put near the top of a mountain in an area they are searching in, or working to help someone.
Awesome my friend:beer::)
 

Alaskan

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Glad you all like it, the transmitter only draws an amp, and on receive the current is about 60 mA all together, so the batteries do last quite a while at the duty rate they use the unit. The alkaline batteries were chosen to force them to swap them out when they are low and use a fresh set, instead of having batteries which may be half charged and all the problems that can cause. That choice was made by someone else, myself I would have used lead acid Enersys Cyclon batteries which can be used longer at low temperatures, but the Alkaline lantern batteries were chosen instead, I suppose, partly due to the weight. If need be, they can use a cord I built with large alligator clips with an external car battery, but that isn't something you keep in your back pack.

They do have a few L-band sat phones, but most of the government agencies up here who would be involved in a rescue use hand held portable radios and they have the frequency of this repeater already programmed into them. Also, hand held radios are just easier to use, its just push the button and talk, satphones require you to call the number and just aren't as easy to use as a push to talk radio, so the rescue group has far more of those than satellite phones.

Often this is placed on a high mountain by a helicopter, they could just fly back and swap batteries or put an external one on it if they needed it, but most missions don't last four days to need to swap them. This is the second repeater in a Pelican case I've built for them, 15 years ago I built their last one, but the case was nearly twice as heavy and larger, they wanted something they could carry easier.

Scary story Pi, I've lost a couple of good friends up here in Alaska who were just out in the wild for fun like you were, one tried to cross a river with a rope attached to his waste and didn't realize there was a tree stump in the middle the rope got tangled with, he didn't have a knife on him to cut loose and the cold water caused him to collapse and drown, with his two young sons on the bank watching him. Another had his climbing rope cut on a sharp rock when he lost his grip and fell, then falling another 100 feet to some rocks below. It's safer just to stay home. Great story about how people were willing to help, that's humanity, when things are at their worst is when we are at our best.
 

diachi

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Here's a VHF radio repeater I built into a Pelican case at work, still finishing it though, needs ID and operating instruction plates installed, but they aren't finished yet.
Awesome! Just saw this! :D

I picked up a pelican case recently, didn't ever think if sticking a repeater in one. I was going to use it eventually for a portable HF/VHF rig.
 
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Let's say so. Physics has special terms to name a lot of things.

Energy density in the context I used it means watts per square centimeter.
You are mixing a dimension (W/cm^2) with a property (energy density but I assume you mean "intensity"). When "energy" is used then units have "joule" (J)


For instance fixed infinity focus for infinity focus would be a different number than focused at a fixed distance,
:thinking:
 

RedCowboy

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Pretty little lasers are right now packed into small cages, unused and unlit, wanting to be loved.

These lasers long to know the warm embrace of a copper and aluminum home of their own and you, yes you can help a laser find a home today.

Give generously to the RedCowboy laser foundation so these lasers can escape their tiny prison like cages and know the warm glow of emitting glorious streams of photons as their creator intended, yes you can help today.

Donations are being accepted right now and you will be blessed with a photo of the laser you helped into a home burning away and releasing beautiful streams of coherent light.

Won't you give today, let your love light up sky, save a laser today, the RedCowboy way. :gh:



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GREAT COLLECTION ALASKAN :gj:

What is that truck mounted octo laser for? Vaporizing tailgaters?
Just kidding, communications right? Is it a visible wavelength?
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