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April 1974 Popular Electronics
 Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
from
Popular Electronics,
published October 1954 - April 1985. All copyrights are hereby acknowledged.
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What stood out to me when
reading this article on walkie-talkies is a statement made near the end where the
author claims regarding loaded whip antennas, "Transmit losses are many times greater
than receiver losses." The last time I checked, passive antennas are reciprocal
devices, so gains or losses should be the same for transmit and receive. Methinks
he either didn't know that, or he meant something else. My main reason for posting
the article is because it pretty much completes the evolution cycle of walkie-talkies,
which started life being called handie-talkies when being developed during World
War II as lightweight, portable 2-way radios that could be deployed in regions
of difficult travel and even carried by paratroopers. Nowadays, most 'serious' handheld
transceivers operate in the 462-467 MHz
Family
Radio Service (FRS) band, rather than in the 27 MHz Citizens Band as did
early models. The neighborhood where I grew up in the 1960s and 70s had a lot of
kids in it, and we boys did a lot of playing war, cops and robbers, detectives,
etc., and often used cheap walkie-talkies as part of the activities. They were usually
so bad that yelling back and forth had more effective range than the radios.
See also
The Walkie-Talkie - March 1955 Popular Electronics,
A
Self-Contained Handie-Talkie - June 1944 QST, and
The New Handy-Talkie - December 1942 Radio-Craft,
Walkie-Talkies: Something for Everyone - April 1974 Popular
Electronics,
A Self-Contained
Handie-Talkie - June 1944 QST,
Inside the Handie-Talkie
- July 1946 Radio-Craft.
Walkie-Talkies:
Something for Everyone
By Herb Friedman
 Children eagerly look forward to getting
a toy walkie-talkie (w-t) for Christmas or birthday presents. To their big brothers,
those walkie-talkies aren't toys but indispensible units for things like relaying
football plays from the stands to the high-school teams. On the top of the heap
with much better w-t's are the CB'ers involved in REACT and Rescue Team programs
where the compact communicators can prove invaluable over relatively short distances.
And outside workers have adopted the w-t as their principal "no-wire" communication
system.
The CB walkie-talkie which began life as a plaything for children has grown into
the most popular communication device of the day. The reason for the popularity
of the relatively low cost w-t that operates on the CB frequencies is due to there
being a model almost tailor-made for any applications. Whether you are looking for
a cheap present for a child, a tone-controlled radio tripper device for woodland
photography, or a pocketful of power for search-and-rescue operations, there is
a CB w-t to fill your need.
Low-Cost W-T's. The basic CB walkie-talkie, priced at less than
$20, is usually a three- or four-transistor device with a super-regenerative receiver
and a simplified single-frequency, crystal-controlled transmitter. Its power input
is generally stated at a nominal 100 mW, making it license-free (anyone can use
it), although the actual input might be as low as 20 mW, providing a dependable
range of only two or three city blocks.
The superregenerative receiver, noted for a sensitivity almost the equal of a
good superheterodyne receiver, is also noted for its poor selectivity. The less-than-$20
w-t might well receive every signal frequency on the Citizens Band, regardless of
the frequency to which it is tuned. Still, the least expensive w-t does make a desirable
gift for children. But for more serious work, one inevitably must look to more expensive
models.
Moving up the ladder to the $25-$50 range, you will find 100-mW models that are
really useful. Featuring superhet receivers and fully modulated 100-m W transmitters,
these w-t's serve a very useful purpose for short-range work. The transmitter and
receiver sections are crystal controlled, and some means is provided for easily
changing crystals.
The receiver generally contains an r-f preamplifier and a 455-kHz i-f amplifier.
The i-f section can provide as much selectivity as can be expected of an inexpensive
5-watt base or mobile CB rig. Models near the top of the price range often feature
an extra stage of i-f amplification, or a ceramic or mechanical filter for more
selectivity to yield performance that approaches that of the better single-conversion
5-watt transceivers.
Unlike the superregen w-t's that usually use small 9-volt batteries with average
lives of 2-4 hours, the low-cost superhet w-t uses some type of "penlight" battery,
whether it is throw-away or rechargeable being left up to the user. Depending on
the type of battery used, you can expect anywhere from 20 to 50 hours of dependable
service before it must be replaced or recharged.
A full 100-mW input power w-t will have a reliable range of about one mile in
open country, less in areas where the terrain is interrupted by hills, buildings,
etc. One important advantage of these units is that they can be used at relatively
short range without overloading the receiver; higher powered models generally overload
at close range.
While there is usually no need for multi-frequency capability, it is conceivable
that you might have to communicate with two or more systems operating on different
frequencies. The higher-priced 100-mW models ($35 and up) can give you two or three
switch-selectable channels, and they often include some form of tone signaling system
to get the monitor's attention. Another feature you get is a "talk-power" modulator,
with speech clipping or compression similar to that found in 5-watt rigs.
The 5-Watt W-T. When you need long-range communication from
a hand-held device, you need lots of power to get through. Consequently, you will
find w-t's with transmitter power inputs ranging from 1 to 5 watts. Power input
definitely determines the price you will have to pay for a unit; so, the cost differences
between models usually represent transmitter input power rather than differences
in operating features. (Any w-t with a power input in excess of 100 mW must be operated
under a CB license.)
Except for the "stripped" models in the $50 price area, most high-power CB w-t's
have features you would expect to find in quality mobile equipment, starting with
a power input jack that permits operation from an ac-operated power supply. All
models have squelch controls, antenna jacks, earphone jacks, and S/r-f meters that
double as battery-condition indicators. Some models have only a battery-condition
indicator.
The circuits in the high-power units are often identical to those used in higher
quality base and mobile CB rigs. Receiver sensitivity is generally 1 μV or better,
while selectivity can be 50 dB or greater between channels.
Depending on total cost (high-power w-t's ranging from $50 to almost $200), you
might have a choice of three to 23 channels coverage. In most cases, 23-channel
models are supplied with all crystals. (You pay for all whether you need them or
not.) One 23-channel model is presently available on a build-up basis; you purchase
only the crys-tals you want as you go along.
For w-t's with less than 23-channel coverage, you add a channel at a time. The
usual two crystals, one for transmit and the other for receive, are required.
As a general rule, the higher power models have some type of "talk power" booster.
Though the high-power w-t's provide extended range, they also prove a decided convenience
for short-range work when portability is a prime requirement. The length of antennas
used with CB w-t's can run up to and beyond 4 ft. Hence, one of the most convenient
accessories to have is a loaded whip antenna whose total length is 12 in. to 18
in. Their short length easily adapts the w-t to belt or shoulder-strap carrying
use.
Unfortunately, loaded whips have very low efficiency. When used on a 100-mW unit,
the signal might not make it the length of a city block. (Transmit losses are many
times greater than receiver losses.) But with a loaded whip on a 3- or 5-watt w-t,
there is still plenty of power available - more than enough to cover a large office
building, school, stadium, or playground.
A secondary advantage of the loaded whip is that the reduction of output signal
power makes the w-t less prone to frontend "jamming" caused by signal overloads.
Of course, the loaded whip cuts down maximum range. So, when you need maximum range,
you can always switch back to the regular whip.
Posted March 29, 2017
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