March 1955 Popular Electronics
of Contents]People old and young enjoy waxing nostalgic about and learning some of the history of early electronics.
Popular Electronics was published from October 1954 through April 1985. All copyrights (if any) are hereby acknowledged.
as early cellphones (Motorola's
, e.g.) required large carrying cases to contain both the
large electronics and the large battery required to operate the phone,
some of the first commercially available portable personal radio sets
came with shoulder straps. Those that didn't have straps had wheels
and a handle. The "walkie-talkie" (originally called "handi-talkies
designs were first seen during
World War II
and then in
In fact, this 1955 article from Popular Electronics was printed shortly
after the end of the conflict in 1953. Don't confuse the radio-based
with the ones that had a pair of wires (sometimes
thousands of feet of it) that did not need complicated circuitry for
over-the-air transmitting and receiving.
See all articles from
By Leo G. Sands
Bendix's MRT-9 portable two-way radio unit for the 152-174 mc.
The Bendix MRT-9 packset in its shoulder-strap
Motorola packset with a monitoring
speaker on top of case.
The Motorola "Handie-Talkie"
for 152-174 mc. band. Case is available to protect set from
Vibrator power supply section of Motorola "Handie-Talkie."
Note the non-spillable storage batteries in unit.
Two-way radio has captured the imagination of the public - here is the
story on available units and operating rules.
The portable two-way
radio has been brought vividly to the attention of the public by "Dick
Tracy." His is the two-way radio which would sell like the proverbial
hot cakes if it really existed. Many are trying to develop a "Dick Tracy"
radio and no doubt someone will succeed.
Today, crime fighters
must content themselves with somewhat heavier and bulkier portable two-way
radio sets. Several excellent portable units are on the market and they
do a commendable job, even if they fall short of the performance of
"Dick Tracy's" wrist radio.
Depending, upon their size and form
factor, they have been called, among other things, a walkie-talkie,
"Handie-Talkie" (a trade name), pack set, "Port-A-Fone" (also a trade
name), and a breakie-backie.
If you buy a pair of walkie-talkies,
there is no assurance you can use them. All radio transmitters, even
flea-powered, hand-carried portables, must be licensed by the Federal
Communications Commission (FCC). Different kinds of walkie-talkies are
designed for licensed operation in different categories of radio services
as defined by the FCC. Equipment for use in the industrial, land transportation,
and public safety radio services must generally meet more rigid technical
standards than equipment to be used in the Citizens or amateur radio
Unless you operate a business which is eligible for
licensing in the land transportation or industrial radio services or
unless you are an amateur radio operator, you as an individual can only
operate walkie-talkies in the Citizens radio band. The Citizens band
is open to all citizens whether for private personal use or in connection
with a legal commercial enterprise.
For use only in the Citizens
radio service on 465 megacycles are such low-priced, hand-carried two-way
radio units as the Stewart-Warner "Port-A-Fone." Here, the range is
limited from a few hundred feet to a mile or more, depending upon local
conditions. This type of unit uses a super-regenerative receiver which
is converted into a self-excited AM transmitter.
The more widely
used and more expensive portable two-way radio units are designed for
operation in either the 25 to 50 megacycle or 152 to 174 megacycle v.h.f.
(very-high-frequency) bands which are reserved exclusively for eligible
commercial enterprises and government agencies.
To meet FCC
requirements, these commercial pack sets employ crystal-controlled transmitters
operable on one or two specifically assigned fixed frequencies within
the band for which the equipment was designed. Fixed tuned superheterodyne
receivers, which are also crystal controlled, are used. Transmitter
and receiver are packaged in the same enclosure along with either wet
or dry batteries.
(Left) RCA's lightweight walkie-talkie for the 25-50 mc. band.
It uses a Western Electric type 500 handset. (Right) Interior
view of typical unit using miniature and subminiature tubes.
When wet batteries are used, they rare of the non-spillable type and
are used to supply filament power and to drive a vibrator power supply
for plate power for the tubes in the transmitter and receiver. Generally,
when dry batteries are used, plate power is derived directly from "B"
batteries instead of a vibrator power supply.
and miniature type tubes are used in commercially available walkie-talkies.
The transistorized walkie-talkie has not yet made its debut and is not
expected to do so, at competitive prices at least, for quite some time.
The antenna used with nearly all of the commercially available
walkie-talkies is either a vertical flexible quarter-wave whip or a
telescoping antenna similar to those used in automobiles. An external
antenna may be used in fixed or mobile applications by removing the
antenna and plugging in a coaxial cable leading to the antenna.
The range obtainable with walkie-talkies is sometimes amazing, especially
when operating in the 25 to 50 megacycle band. A range of 8 or 10 miles
between a walkie-talkie and a higher powered base station is often reported.
However, much depends upon terrain conditions.
Pack sets are used by many railroads to extend communications
to the man on foot. The unit shown here is manufactured by Hallicrafters.
Operating in the 152 to 174 megacycle band, the range is generally considerably
less. However, communication between a walkie-talkie on this band and
a higher powered base station up to 8 or 10 miles has been achieved
but not as regularly as when operating in the 25 to 50 megacycle band.
The range between a pair of walkie-talkies is generally quite
limited because of the power output of the transmitters and because
of the low effective antenna elevation. Of course, the range can be
several miles if one walkie-talkie is operated on a hill top and the
other one is within line-of-sight or at a point where signals are easily
In railroad yards, for example, many have been disappointed
to find the range attainable between a pair of pack sets is so short
as to be unsatisfactory. This is particularly true when one or both
walkie-talkies are carried by personnel standing or walking between
freight cars. This would also apply in congested areas as in city streets
lined by tall buildings or many trees.
The cure in such cases
is to employ a relay station if permitted by FCC regulations in the
service in which the equipment is to be operated. When using a relay
station, two different radio frequencies are required, one for transmitting
and one for receiving.
Motorola and General Railway Signal Company
have developed novel portable transmitters for one-way radio communication.
They are not much larger than a flashlight and are primarily used in
railroad yards where personnel on foot talk out over a portable transmitter
and receive calls and replies over a public address system. A typical
walkie-talkie like the MRT-8 manufactured by Bendix weighs only eight
pounds and is available for hand carrying or for mounting on personnel
with suitable straps. Hallicrafters manufactures portable two-way radio
units which can be adapted for installation in motor vehicles. Power
is derived from the vehicle's electrical system.
Three versions of the Hallicrafters "Littlefone." (Left) The
standard model with handset. (Center) Unit adapted for under-the-dash
mounting in a car. It is powered by car battery. (Right) "Littlefone"
with a 4" speaker mounted on case.
Surplus walkie-talkies offered at bargain prices are seldom licensable
without extensive modification. Very few, if any, military surplus portable
radio telephones can be readily modified for use in the 25 to 50 mc.,
152 to 174 mc., or the 450 to 470 mc. bands. Some, however, can be modified
for operation in one or more of the amateur bands. However, to be eligible
to operate walkie-talkies in the amateur bands, it is necessary to possess
an amateur operator's license which requires taking a code test and
passing a written examination on radio theory and FCC regulations.
In the land transportation, industrial, and public safety radio
services, persons using mobile and portable stations do not need operator's
licenses although the operator of an associated base station must possess
a restricted radio telephone operator's permit. Although a station license
is required for Citizens band walkie-talkies, an operator's license
is not needed.
It is possible to build your own walkie-talkies
for use in the Citizens band or in one of the commercial radio services.
However, to build such equipment so that it will comply with FCC regulations
requires considerable skill, a vast amount of precision test equipment,
a good deal of time, and ample funds. It is generally cheaper to buy
factory-made equipment. Commercially available walkie-talkies cost from
$200 to $500 each. Posted
February 17, 2014