RE: [BCD396XT] Air Band Radio Power
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My piper Warrier II had a 25 watt radio; Garmin commercial radios range
from10W to 25W --- one model was selectable at 10W or 16W.. but be careful
about the specs... some are spec'd at 16W but are 5W carrier and 16W PEP
(Peak Envelope Power - the power in the AM Sidebands that carry the audio
information). Bendix KLX 135A is 5W (7W nominal); Bendix KY 196A, pretty
common, is rated at 16W (probably PEP).
ATC radios are about the same power levels. You can imagine the problems at
a large airport if high powered radios were used all operating at close
range for multiple Tower and Approach frequencies, ATIS, Ground control,
clearance, terminal ops, maintenance, ground vehicles, etc..
I wasn't able to find anything about VOR power levels (108 TO 118MHz) but
there is quite a bit of data on their characteristics and ranges:
Terminal VOR - 1,000 to 12,000 feet 25nm (nautical miles - statute miles
divided by 1.1)
Low Altitude VOR -- 1,000 TO 18,000 feet to 40nm
High Altitude VOR - 1,000 to 14,500 to 40nm; 14,500 to 60,000 to 100nm;
18,000 to 45,000 to 130nm.
As you can see, you need some altitude to hear VORs at any distance. You can
hear them pretty well on the ground if you're within a few miles of one. By
the way, these are located all over the map and not necessarily at
I haven't seen data on ATIS transmit power, but I can tell you on the ground
you need to be within a few miles generally, but I can hear ATIS from about
30 miles from relatively small hills.
Mike Hopkins K1VLB
- And when we are coming into an airport at 40,000ft we park the Center Comm radio on the ATIS and it usually breaks squelch in the neighbourhood of 200+ nm.
Antenna height is everything!!:)
--- In BCD396XT@yahoogroups.com, "Michael Hopkins" <mhopkins735@...> wrote:
> I haven't seen data on ATIS transmit power, but I can tell you on the ground
> you need to be within a few miles generally, but I can hear ATIS from about
> 30 miles from relatively small hills.
> Mike Hopkins K1VLB