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Old 12-08-2013, 02:04 PM
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DaveInDenver DaveInDenver is offline
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Join Date: Jun 2006
Location: Larimer County
Posts: 6,550
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Do you need a maintainer/supply? I have a IOTA DLS-45 that a Group 27 AGM just sits on 24/7. I'd like to put the battery in the truck somehow but in the interim I'm probably reconfiguring to sit the battery on stand-by float with an external controller using my regular power supply. So the switch over is automatic and I can eliminate the IOTA.

FWIW, I run my APRS beacons at low power all the time, which is 5W. You're either going to get packets in or you're not. Using Friis Equation the difference in going up an order on the power is 3 times the range, all things being equal (unity gain antennas, -65dBm received signal strength at 145MHz). But in real life you can figure 5W to 50W will get you roughly twice as much effective range safely in most any condition since simplfied Friis doesn't account for true path loss. It can, but the formula is more complex and I'd have to stick it into a spreadsheet.

A lot of hams do the numbers game with mobiles and buy 75W radios. The difference in range between a 50W and 75W radio is a bit more than 20%. IOW, the 50W would be reliable to say 65 miles the 75W would get you the same signal strength at 79 miles on VHF. As you go down in frequency the power differences become quite a bit more significant. At 7MHz the difference in 50W and 75W is 350 miles, 5W gets you 435 miles and 50W would go 1,400 miles (for the same received strength).
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