Real World Ranges for CB, FRS,
GMRS and MURS Radios
Testing Results Part Two :
Professional Grade Radios
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A 'professional' grade
radio often looks similar or identical to the consumer grade
ones, but can cost up to ten times as much money.
Are they worth the
considerable extra cost?
Part 4 of a 5 part series - click for Parts
One
Two
Three
Four
Five |
Consumer grade radios have very
limited range, no matter what their manufacturers might claim to
the contrary, and there is unlikely to be much difference
between radios optimistically claiming '5 mile range' and those
claiming '7 mile range' - neither are likely to even reach a
mile in normal urban conditions.
Professional grade radios
generally offer more power, the option of adding an external
antenna, and better transmitter and receiver circuitry.
In this part of the series, we
compare professional grade radios with consumer units to see
what type of extra range you can expect.
Testing Protocol
A friend kindly came around,
and brought with him two Vertex VX-400 two-way radios, plus
various different antennas.
The Vertex unit has 5W of
transmitting power, a high quality receiver circuit, and can be
used with external antennas.
He sat on my deck, with one
of the two Vertex radios, plus one of my Midland G225 radios.
He had three different antennas - the short stubby antenna that
came with the radio as standard, an alternate short 1/4 wave
antenna, a longer 1/2 wave antenna, and a 'Tiger Tail' clip on
modifier.
I drove around the same
route as before, with a second Midland G225 (low quality
consumer grade radio), a Midland G11 (mid-grade radio), and the
other Vertex. I had the standard antennas for the G11 and
Vertex, plus two external roof mount antennas - one being an
inexpensive generic roof mount antenna from Midland, and the
other being a high quality, ~ $100 5/8 wave B4503 antenna from
Antenex. Both external antennas claimed +3db of gain.
Results & Analysis
The importance of a good
receiver
At 0.3 miles, when talking
from a G225 to the other G225, the signal quality was assessed
at 2 (on a 5 point scale), but when talking to a Vertex, the
signal quality improved to 4.
The largest factor in the
improvement of signal was due to the better receiver circuitry
in the Vertex, which has a good sensitivity rating of 0.25 uV.
At 0.5 miles, the quality
between the two G225s was almost zero, and it wasn't practical
to talk on them. Using a Vertex to receive improved the
quality up to 2, and using a Vertex unit both to transmit and
receive increased the quality up to 4.
The importance of transmitting
power
At 0.5 miles, calling from a
2W G225 to a Vertex resulted in a signal quality of 2.
Changing from the 2W G225 to the 5W Vertex saw the signal
quality increase up to 4.
In general, using the Vertex
as a transmitted seemed to increase the clarity of the signal
that was received (on either radio) at the other end, but did
not appreciably increase its transmission range.
The importance of a good
antenna
At 1 mile, where the two
G225s could not talk to each other, neither also could the two
Vertex units talk to each other using their standard antennas.
But both the Midland G11 and
the Vertex could communicate back to the other Vertex when using
an external antenna.
There seemed little
difference in performance between the Antenex antenna and my
cheaper Midland generic antenna.
The external antenna made a
major impact both on the strength of transmitted signals and
received signals.
Maximum overland Range
We managed to get 1.3 miles
between the Vertex with Antenex external antenna and a Midland
G225, in a suburban environment.
Over Water Range
We next changed location.
I drove to a waterside location on Mercer Island, and Dan then
drove across State Highway 520, from Redmond to Seattle.
When he was directly
opposite me, across the water (range of between 3.2 - 3.6 miles)
we could communicate clearly while Dan was using a Vertex and
external antenna, and I was using my 2W G11 and internal
antenna.
With Dan using his Vertex
and external antenna, and me using my G11 and external antenna,
we managed to communicate an incredible 6.15 miles, with 4.7 of
those miles being over land and only 1.45 miles being over
water.
This was a stunningly good
result. However, it was a 'one off' rather than a regular
reliable event. Depending on the relative elevation of
where Dan was and where I was, as he drove from the point 6.15
miles away and then generally towards me, the quality of signal
would vary and sometimes we would lose contact.
The Most Important Factor
Essentially, we were
experimenting with three main variables :
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Transmission power
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Receiver sensitivity
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Antenna
Extra transmission power did
not have as much impact on performance and range capability as
did the other two factors. For example, at a 1 mile range,
the 5W Vertex could not communicate with the other Vertex while
using its standard antenna, but the 2W Midland G11 could
communicate via an external antenna.
We would consider that a
good antenna is the most important factor - and also the
cheapest factor to improve.
A good receiver design is
the second most important factor, and transmission power is the
least important of the three.
A good antenna increases
both the range which you can transmit to and receive from,
whereas a good receiver only increases the range you can receive
from, and a powerful transmitter only increases the range you
can transmit to.
A 'good' antenna need not be
large or complicated or expensive. Because the type of
antenna that can be found built in to a radio set is very
inefficient, just switching to a better quality external antenna
on the radio itself gives you an immediate boost in range, and
going to a remotely located antenna (on the roof of your vehicle
or house, for example) you can get still more benefits.
Professional quality radios
allow for external antennas and have high quality receivers.
Consumer quality radios might have a similar power rating, but
their very very inefficient fixed antenna and poor quality
receiving circuit handicap them severely and make them much
poorer in real world usage.
Summary - Should You Get an
Expensive 'Professional' Radio
The answer to this question
depends on how you're going to be using your radios, and what
sort of reliable working range you need.
With consumer quality FRS
and GMRS radios so incredibly inexpensive these days, perhaps
your best strategy is to spend $50 to get a pair of consumer
grade radios and see if you're happy with the quality and range
you get from these units.
See also Parts 1, 2, 3 & 5
In
Part 1 we explain the different types of personal radio
services available to you, and what they variously mean.
In
Part 2 we discuss how it is that manufacturers can claim
ranges of 'up to seven miles' when the effective range - as
tested by us - is sometimes as little as one twentieth the
claimed range. Many factors influence maximum range - some we
can influence, most we can not. In particular, read the
startling truth about the importance of transmitter power to
give you more range.
In
Part 3 we give you real world test results of 'consumer
grade' radios and help you
choose which is the best system for your needs.
In
Part 5 we explain the confusing
mismatch of channel number allocations to different FRS/GMRS
radios.
Related Articles, etc
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Originally published
18 July 2003, last update
21 Jul 2020
You may freely reproduce or distribute this article for noncommercial purposes as long as you give credit to me
(David Rowell - KF7VVM) as original writer.
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