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Hi every one,
Steve's experiance has obviously been a good one, however, although the
bucks are nice there can be several drawbacks. After reading some of the
other comments I thought there needed to be some information shared.
As always, "Your milage may vary" applies in a case like this.
Dan
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Message-ID: <33293F57.238E@erols.com>
From: Dan Weisenburger <kw4t@erols.com>
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To: Larry Reader <readerl@goliath.sunyocc.edu>
Subject: Re: [CQ-Contest] Anyone ever set up near a Cell Phone Tower?
References: <9703131406.AA15274@goliath.sunyocc.edu>
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Hi Larry,
I'm certainly GLAD you asked about Cellular and Contesting. I'm a Cellular
Engineer,
presently doing Data Performance Engineering (Glorified Paket Radio) for Bell
Atlantic
NYNEX Mobile. My resume' includes time spent doing cellular engineering work
in Latin
America. There are several issues to be examined.
1. Not all cellular base stations are created equal. Some manufacturers
use
extremely noisy, and raspy microprocessors in the base station
controllers.
What a given Cellular Service Provider uses today could be replaced by
a
completely different brand tommorrow (i.e. Motorola equipment is
replaced by
Harris). This is a very common occurance in the Cellular Industry.
These are
indusrial computing devices and RF Generators. All Cells that I've
seen use a
3 to 70 Mhz Master Oscillator and multiple IF's the mixing and
multipliers used
vary widely.
2. Most cells have multiple HF Power supplies. These supplies are
industrial
strength and can produce incredible amounts of noise.
3. Good help is hard to find. Cellular companies are often slow to
identify
degraded "Type N Connectors" at the antenna jumper or bad antennas
which are
causing arching even though this can sometimes be heard on an analog
phone.
Many companies add more radios to a site than good engineering practice
says is
prudent. Although each radio is rated for 100 to 500 watts ERP
(depending upon
the type of license and location), the composite power often exceeds
that for
which the antenna is rated at a busy cell site. Quality antennas are
seldom used
in Latin America, and just as in Ham Radio, the capabilities of the
antennas are
often fall short of the claims made in the catalog. Many Latin
American
Cellular Companies uses Duplexors to gain channel capacity on a tower,
Most of
which cannot handle Composite power levels in excess of 500 watts.
Many
companies, even here in the States, overdrive the linear amplifier
circuits into
non-linearity. This wipes out the UHF bands for EME or TE.
4. The typical shelter is made of fiberglass/frame construction or
concrete. Some
are bullet resistant. Special effort must be made such as adding a
screen room
when the site is placed in a high ambient RF Field such as a strong
local
broadcast station. This is mostly done to assure proper operation of
calibrated
test equipment which is brought into the site. It is not done to
protect a Ham
Radio Station.
5. Many Cellular Towers are not properly grounded, present numerous ground
loops,
and often have additional, unterminated wires placed for future use
which may be
noise radiators on some frequencies. In addition, properly grounded
towers do
take lightning strikes rather well and disipate the lightning into the
ground.
Will it get into the ham ground? Some Cellular companies place corona
discharge devices on their towers which can possibly wipe out the 160
and 80
meter bands (especially the weaker signals).
.
I could go on and on but bandwidth and time (mostly time) precludes it. The
short
answer is: DON'T DO IT!
See you in two weeks in the WPX, I'll be pluggin away on 40 with my 100 watts
ERP
If I ever don't work you guys in a contest I'll know that the tower went up.
73 from Lake Moneysgone, Dan, KW4T
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