CALSTAR Air Ambulance Low Power Repeaters

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I recently came across CALSTAR frequencies page on Radio Reference

https://www.radioreference.com/apps/db/?aid=4011

According to those FCC licenses associated with those frequencies, it says that their repeaters and mobile radios are only transmitting at 10 watts, with some even as low as 3 watts. I was wondering if this was an error by whoever applied for the licenses or if they actually do transmit with such low power and if so, why?
 

ko6jw_2

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They are talking from mountain top sites to helicopters. It is mostly all line of sight. High power is not required. Most aircraft (AM) communications are low power as well. I once worked a station that was aeronautical mobile with an HT at about 200+ miles. He was at 20,000 feet. Also, I've worked ham satellites with 5 watts. Remember the old directive - use the minimum amount of power necessary to establish the contact.

By the way a CalStar repeater is in the building at the base of the towers in my picture.
 

mmckenna

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There are rules in Part 90 that specifically address radio use from aircraft.
Some frequencies are limited to 10 watts or less. 700MHz is limited to 2 watts or less.

This is done specifically to prevent interference to co-channel users. Since the aircraft can be up pretty high, there's no need to use a lot of power and risk interference with other users on the same frequencies. And there's no need to run a bunch of power on the repeater side if the aircraft can only run lower powers.
 

scannermike11

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be carefull with these a lot of are not right

first the 157 range freq are inputs only you will not much on them
i have been tell the web site people to drop these but nobody whats to listen
 
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Oh ok, that makes sense. I just would've thought the repeaters would have a little more oomph just in case there was an obstruction or terrain blocking the signal. I'm so accustomed to public safety repeaters being 100+ watts in VHF.
 

mmckenna

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More power might help the repeater slightly, but usually it doesn't fix topological shielding issues. Since the aircraft is limited, it wouldn't be able to talk back.
 
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