Yea- Here in the flat lands we get excited about bieng on a tower or structure
300-500ft! Obviously the big buildings in the city are the tallest places
around- but they are RF nightmares and usually have high $$$ price tags for
rent. Most of the systems with tx on those buildings have multiple reciever
sites because the noise floor in the city makes rx not as good as it should be
(fun just to drive around downtown with an icom mobile- the s-meter is always
pinned from the junk floating around and the crappy rx design of the non-moto
or ge radio) So the rest of us poor hams settle for water towers, apartment
buildings, things like that.
Then again, if your lucky enough to land a 300-500 ft tower site you have the
joy of the hardline expense!
I have two UHF systems. Both are balanced in my opinion, maybe a little on
the elefant side if anything. One is at 130' agl on a water tower, DB-420 on
top fed with 7/8" hardline and the TX set at 18 watts into the duplexer- 10
miles for portables and 25-30 for mobiles is what we get typically. The other
is at 320' AGL on an old microwave tower. It's also a db-420 on top, 7/8"
hardline (for now- it's what ma bell used on the orignal install) and a 75W
micor pa. it gets 15-20 miles for protables and 30-50 miles for mobiles. As I
said before- it's out in the cornfields and plays better away from the city
than to the city. The other box is in the suburbs.
Only mountains around here are the landfills;). However- I can be to one of
my sites any time of year from work in 5 mins and the other from home in 10. No
4WD required!
In summary- I would estimate systems here, and others can chime in with there
observations- the better ones get 30-50 mile radius for a good mobile, and the
average ones get 10-20 mile radius for the same. Onlytime we get 100 miles is
during a band opening.
Which opens up another can of worms. On VHF, coordination gets you 120 mile
protection. Most systems cannot do half of that, and here in the northern part
of the state 2m pairs are full. The IRA has done a great job in the past few
years of getting everyone taken care of and utilizing the spectrum more
efficently by working out short space agreements and utilizing full time PL.
Debate it as you may, the PL requirement DOES help the situation and gives
everyone a chance to play.
Tom
W9SRV
Keith McQueen <[EMAIL PROTECTED]> wrote:
I guess it's a different world out here in the wild wild west. Very few
machines run more than 30 watts. Of course with our 10,000+ foot granite
towers we don't need any more. Some machines have 100+ mile (radius) coverage.
Keith McQueen
801-224-9460
[EMAIL PROTECTED]
-----Original Message-----
From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of
TGundo 2003
Sent: Friday, October 19, 2007 8:08 PM
To: [email protected]
Subject: Re: [Repeater-Builder] Re: TPL amplifier - aka repeater operation at
the 250 watt power lev
Imagine the fun we have at the Illinois Repeater Association meetings
between the "Chicago" and "Downstate" guys? It's the same with politics too ;)
Well, the last few meetings have been good, thanks greatly in part to the
supurb job the IRA has done.
Anyways, I a "downstate Chicago" guy, I live in the farmfields 45 miles south
of the city. While I will not argue that there are some alligator systems in
the city...and suburbs....
Be careful of acousing any of those machines of being "gluttons". I'm not
sure which machines you had in mind, but probably the widest coverage 2m
machine in the city is CFMC on 146.76. They have several reciever sites, and
run modest power off one of the tallest buildings in the city- 45 miles away
here at my qth running around mobile they are usually between 1/2 and full
scale on an icom with a 5/8 nmo on the roof of the surburban. Of course I can
access the system full quieting, so it's bretty balanced for the users in the
greater metro area.
Now- during a band opening I'm sure it can put out a good footprint. FYI-
during an average opening in the morning or evining during the summer we can
hear the downstate repeaters just fine as well. The corn fields don't stop
much, the city is a different story. One of my uhf systems is in the cornfields
south of the city, and it plays much farther to the south than it does to the
north into the city. (omni antenna on top of a 300' tower)
In comparason- one of the largest UHF systems in chicago, 16 recieve sites
last I heard, is on one of the tallest buildings as well, and for the last few
years has been running on exciter power (4-5 watts) that is being divided to
three panel antennas (to put the footprint away from the lake), and on 1/3 or
exciter power at that height from the panel antenna in any given direction it's
very common to hear the output 70-80 miles away on a mobile with average
conditions. Im sure on a good base 100+ miles is pretty easy, and during an
opening, well, who knows. Does that make them a glutton? If you could put your
antenna at 1300' AGL with a relativly short feed line, wouldn't you?
There are issues in the metro areas & city with building penetration,
intermod & general high levels of rf garbage, & topography around the city with
a few "holes" and river valleys where it can be hard to recieve the talkout
from the city. Skipp covered the rest well in his response. If there are
specific machines you notice, please contact me directly, I would like to know
which ones. I have a pretty good knowledge, and know people who have more
knowledge of many of the boxes here, maybe I could help research this for you.
I would just be careful of the glutton accousations, that's all.
73
Tom
W9SRV
Al Wolfe <[EMAIL PROTECTED]> wrote:
> Having a very high-level flamethrower repeater around is not only
> a great communications resource... if the hardware operates well
> it's also impressive on your technical resume and a lot of fun to
> operate.
So in other words, it's just an ego trip. These repeaters are commonly
known as Alligators.
We in downstate Illinois suffer from the two meter glut of RF out of
Chicago. There they have repeaters there with dozens of receiver sites and
multi-kilowatt ERP transmitters, usually running about half scale 150 miles
away. But we cannot get into their systems running legal power. But they say
they have "balanced systems"? What a crock!
If a repeater is full scale and I can't get into it with 150 watts then
something is very wrong!
Al, K9SI
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