Jim,
So, are you saying that range is unlimited at UHF as
long as it's 'line of sight'?
Assuming that the transmitter's output for both radios
are the same, and both receiver's sensitivity is the same,
and both have a usable range of 3 miles. That means for
the two stations to hear each other they have to be within
three miles of each other. At 6 miles neither will be able
to hear the other because they would both be out of each
other's usable range. Wouldn't matter what the 'line of
sight' distance was. Propagation will make a difference,
but we're talking about the 'normal', every day state of
propagation.
'Doc

Doc,

Normally, HTs will be limited to line of sight. The problem is that normal
line of sight is only about 3 miles to radio horizon for a person standing
on level ground. Get up on a ladder, and the horizon stretches out farther.
We're not talking propagation enhancements, just a simple formula which
takes the station's height above average terrain (in feet), double that and
take the square root. The answer is the range to radio horizon. 5 feet (to
a handheld antenna) times two is 10. SQR(10) is a bit over 3 miles. 6 or 7
miles max. Get in the second story of a house. Figure 11 feet (up a few
feet to the first floor, another 8 or so to the second floor) and add that 5
feet from that floor to the HT. Now 16 doubled is 32. The square root of
that is somewhat over 5. I would suspect a range of 10 to 12 miles between
two handhelds equally elevated over average terrain in that case. I was on
the 21st or 22nd floor of a high rise. Figure over 200 feet up, plus 600
feet above average terrain (yes, it was on a hill). 800 feet and I won't
add the extra 5 feet. SQR(1600) yields 40 miles to radio horizon. Now
figure in the repeater height. Should that repeater be up a total of 2000
feet (including hill, tower, antenna, whatever), it will have a range over
60 miles to its' horizon. As long as my horizon intersects its' horizon
with no obstruction, I can use that repeater. The 3.5 watts on my HT is not
a problem; my antenna gain is around 6 dBi and I'm sure the repeater antenna
gain is way over 10 dBi. Plenty of power. I'm talking 24/7 communications.
I've had a few chats over (and can raise at any time of day) the Toronto
repeater. Definitely more than a couple of miles. Way more than a couple
of dozen miles too


73 from Rochester, NY
Jim


"'Doc" wrote in message ...


Jim,
So, are you saying that range is unlimited at UHF as
long as it's 'line of sight'?
Assuming that the transmitter's output for both radios
are the same, and both receiver's sensitivity is the same,
and both have a usable range of 3 miles. That means for
the two stations to hear each other they have to be within
three miles of each other. At 6 miles neither will be able
to hear the other because they would both be out of each
other's usable range. Wouldn't matter what the 'line of
sight' distance was. Propagation will make a difference,
but we're talking about the 'normal', every day state of
propagation.
'Doc


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.502 / Virus Database: 300 - Release Date: 7/18/03