September 1932 Radio News
Wax nostalgic about and learn from the history of early
electronics. See articles from
Radio & Television News, published 1919-1959. All copyrights hereby
This past Monday marks the first anniversary of the massive forest
fire in the White Mountains of Arizona that claimed the lives of
firefighters, so I thought maybe this story from a 1932 edition
of Radio News would be an appropriate recognition of their
sacrifice. Firefighters of all specialties have relied on radio
communications nearly since its inception, and particularly once
battery-powered versions became available for portability. It is
hard to imagine a time when such a convenience - even a necessity
- was not part of the standard firefighting outfit. Nowadays the
radios are compact and clip onto a shoulder lapel, but in 1932 the
vacuum tubes, large transformers and batteries meant even a primitive
radio was in the form of a harness-mounted manpack (a word not yet
coined at the time). The portable half-wave dipole antenna in the
picture looks almost exactly like ones I have see today advertised
in QST magazine.
Radio Fights Forest Fire
When the Erstwhile Friend of Man Turns Enemy
Fire in the forests is a cataclysm so awful and so hard
to escape that all of the living kingdoms are affected by
it. The plant kingdom, attached as it is to mother earth,
finds no escape except as is afforded by man's ingenuity
in stopping the progress of the flames. Bacteria and insects
are destroyed, it is true, but their mobile abilities soon
cause replacement. Animals and man, equipped as they are
with instinct and intelligence, fear woods fires as a common
enemy and often flee side by side. Radio is now giving man
new tools and new speed in fighting fire in its first stages,
while it is still small, to prevent widespread conflagrations.
The forest Ranger up to this time had to rely upon primitive communication
methods in fighting great fires in our National forests. He has
hit the trail to carry word of a conflagration either by horse or
afoot. But now radio comes to the rescue with two portable transmitter-receivers
that contact headquarters within a few seconds bringing necessary
help and equipment in short order
By George A. Duthie*
Portable radio receiver-transmitters for emergency communication
in the national forests is a recent achievement of the U. S. Forest
Service. It is an achievement hailed with enthusiasm by forest officers.
Since the day when the radio telephone was announced forest rangers
have dreamed daydreams of the time when a ranger on leaving
for a trip to the back country, would slip a radiophone into his
pack, along with his grub, and be able to report back to
headquarters from the deep woods or from beyond the high ranges.
"An impractical, futile dream," said experts who were appealed to
for help to solve the problem. But the ranger "amateurs" unfettered
by knowledge of radio engineering that recognized this futility,
substituted enthusiasm for learning, and trial-and-error experiments
for fundamental research, to achieve the impossible. The dream has
now come true. Its final achievement was marked by a recent order
for the construction of 105 portable and 27 semi-portable radio
sets of a special Forest Service design. It is the first step toward
equipping the field force with this long-sought solution for its
emergency communication problems. It is the culmination of 14 years
of research on radio transmitter-receiver sets that can be carried
about in the forests and set up at will for temporary emergency
Although both sets are portable radio transmitter-receivers,
the smaller instrument is referred to as the "portable" because
it is so light that it can be carried about in a ranger's
back-pack. It weighs only 10 3/4 pounds including batteries and
antenna and is literally a hand radio set which the forester can
carry right along with him as he works (See Figure 1). For the sake
of lightness the phone transmitter is dispensed with and the instrument
transmits code only - but it receives voice! The larger set is called
"semi-portable" to distinguish it from the portable. It is a radio-phone
(receiving and transmitting) handling voice as well as code. It
weighs about 60 pounds and may readily be transported any place
where a pack-horse can go.
In the forests the communication problem is present on almost
every job. Whether it is fire patrol or fire suppression, building
roads or trails cruising timber, rescuing lost persons or inspecting
range, there is always need for communication. The work is spread
over thousands of square miles of rough timbered territory and the
efficiency and speed with which it is done is directly affected
by the efficiency of the communication system in quite the same
way that field operation of an army depends upon its communication
service. Between points of permanent activity, such as ranger headquarters
and lookout stations, telephone lines have already been built. There
are 40,000 miles of government-owned lines in the forests, and approximately
100,000 miles of commercial and private lines, all of which are
available for official use and yet less than 20 percent. of the
territory lies within convenient reach of a telephone line. There
are 200,000 square miles of territory without communication service
except by messenger or, temporarily, by stringing insulated emergency
Forest Service Photos
The Ranger's Portable Radio Pack
Figure 1. Special forest service radio pack, weight ten
pounds, range ten miles
The use of the latter type of communication has been confined
principally to large fires where it has rendered valuable aid, but
it is not satisfactory because it is slow, expensive and generally
inadequate. A crew of men will toil for days to reach the fire camp
with an emergency line and the pressing need for it is sometimes
past before it is completed. It is costly because it is difficult
to lay down and maintain, and frequently the wire is not worth the
cost of salvage after the emergency is over. It is inadequate because
it furnishes connections only to the supply base. A wire line cannot
be maintained to the rapidly changing fire front where sweating
crews are waging a real battle. It is here that the communication
need is most acute, for the fire fighters may be frantically calling
for help but their message will speed no faster than a runner can
travel. The work of the various crews attacking the fire on several
sectors must be correlated, but the officer in charge can receive
his reports and send out instructions only by a messenger who may
take an hour (or many hours) to reach his objective.
Minutes Count at a Fire
The radio solves this problem, for it will move right along with
the crews. It takes but a few minutes to set up the instruments
and its message reports the situation to headquarters at the instant
- not the situation as it was an hour or five or ten hours ago.
I have timed a forest officer who, without hurry, unpacked a portable
set, hung up his antenna between two trees, and established communication
with a distant station in twelve minutes. In fire suppression work
minutes count and that is why the radiophone is regarded as an achievement
of great importance in forest protection. The patrolman or the "smoke
chaser" hunting incipient fires or the crew boss on the fire line
may now carry his communication with him and contact headquarters
at will (See Figure 2).
How often do small fires become raging conflagrations during
the interval while re-enforcements are being summoned? Perhaps a
margin of thirty minutes in arrival time would have been sufficient
to stop the fire in its first run. The portable set will give the
forest officers the benefit of that margin.
Radio will not, however, replace the telephone lines for regular
service between permanent stations. It will supplement the wire
system and provide temporary emergency communication for 80 percent.
of the forest territory that is out-of-reach of the wire lines.
The equipment designed by the Forest Service for its work consists
of two short-wave sets; a 3-tube portable for the patrolman's pack,
light, compact and sturdy, which transmits code and receives voice;
and a 6-tube semi-portable set which can be readily transported
by pack horse or automobile and which transmits and receives either
code or voice.
The outstanding features of the portable set are its light weight;
its compactness; its simple, rugged construction; and its low cost.
These four features, together with dependable service under the
peculiar atmospheric conditions encountered in forests, comprise
the essential requirements that the set had to meet before it could
be adopted. Its power plant consists of a single 140-volt B battery
and an A battery of two flashlight cells which have a life of seven
hours. The power of the transmitter is too small to be measured,
but its C.W. range is from 10 to 15 miles - which is enough for
its purpose. Exclusive of B battery and antenna, the entire equipment
is contained in an aluminum box 6 by 8 by 9 inches. It weighs but
a trifle more than 10 pounds and can be fabricated for $50.
Semi-portable Ranger Set
Set-up at Field Headquarters
Figure 3. This semi-portable radiophone can be carried
by motor or pack horse and set-up in a safe location near
the fire to contact rangers on the fire line
The semi-portable radiophone (See Figure 3) weighs 60 pounds
and has a range of 10 miles for voice and 20 miles for code. Its
power consists of two 200-volt B batteries and an A battery of three
No.6 dry-cells. It is constructed with the same rugged simplicity
as the portable set. While it is too heavy for a man to pack far
over mountain trails, it will stand packing on a horse or by automobile
over rough roads.
The scheme of use for the two sets is to place the semi-portable
at the lookout station, the fire camp or construction camp or any
other field job when the short period of occupancy of the camp and
the distance from a telephone line renders wire communication unavailable.
The portables will be carried by the field-going men who are traveling
on foot or by saddle horse. At the lookout station, the radiophone
will act as central station to which the "smoke chasers," who are
dispatched to investigate smokes, will report back with the portable
C.W. sets. On large fires, the crew bosses and patrolmen will carry
the portables on the fire line for reporting to the central camp
where a dispatcher will be constantly on the air with a semi-portable
radiophone. A contemplated development for camp set-up is an amplified
receiver which will pick up the signals from the field sets and
make them audible without keeping the dispatcher with his ears glued
to the headphones.
The history of the development of this equipment, like that of
most new equipment, has been one of long research, many discouragements,
threatened abandonment and a slow breaking down of the main obstacles
and final success in a climax of feverish enthusiasm. The first
attempt to use radio in forest work was made immediately following
the World War with long-wave equipment. It was a complete failure
but it served to discover some of the special problems of radio
transmission peculiar to the conditions in the forests. These problems,
for some years, appeared to be insurmountable obstacles the adaptation
of radio to forest communication.
The chief Obstacles Were:
1. The absorption of radio energy by the green timber, which
to overcome would, it seemed, require much more power than could
be provided in a portable set. 2. The shadow effects of rough topography.
Under high mountains there might be "dead spots" from which low-power
radio signals could not emerge. 3. The deadening effect of static
and fading in the mountainous country, an effect that varies for
different wavelengths and for different periods of the day. 4.
The difficulty of erecting long antennas in the forest where the
thicket of undergrowth and swaying branches of trees would interfere.
5. The mechanical difficulty of constructing a set with a combination
of extremely light weight and the sturdy construction which is necessary
to withstand the hazards of transportation in a wilderness country.
6. Simplicity of design which will obviate delicate adjustments
and tuning so that the apparatus can be operated by inexperienced
and unskilled men.
It would be a simple matter to build radio sets that would overcome
any one of these obstacles, but to successfully meet all of them
in combination presented a discouraging, yes even hopeless, problem
for many years.
Inside the Portable
Figure 6. This inner view shows the details of the c.w.
transmitter-receiver illustrating compact arrangement.
Following the failure of the first attempt to use radio, nothing
more was done for several years save that some of the more radio-minded
members of the service kept the idea simmering until in 1927, Dwight
L. Beatty, an inspector, made some interesting demonstrations with
a small short-wave "bread-board" set which resulted in his detachment
from other duties and his full-time assignment to the radio problem.
Beatty first canvassed the field of commercial sets, especially
airplane radio, but found nothing that would meet the forest requirements.
Radio engineers and experts were interviewed, but they offered no
suggestions more than to say that the problem opened up a field
of research in which they could see little opportunity for fruitful
work. It became obvious, therefore, that if radio-in-the-woods was
to become possible, it must come through amateur experimentation.
So Beatty set to work. At the outset, his purpose was to discover
the effect of absorption of radio energy by green timber and the
nature of the interference encountered in the shadow of rough topography.
He found that the loss in signal strength, in timber as compared
to an open setting, ranged as high as 35 percent. He also discovered
that the shadow effect and fading in the mountains varied in wide
limits for different wavelengths and that these variations changed
during different periods of the day. For example a 91-meter signal
at noon might be completely smothered but after 4 o'clock it picked
up in volume while from the same station a 55-meter signal which
was strong, throughout the day, faded away at night. He found also
that some types of equipment were more sensitive to these effects
than others, which led him into extensive tests of different combinations
of parts and hook-ups. He worked diligently for three years, endlessly
building sets, testing them under field conditions, tearing them
down, rearranging and reconstructing, always searching for improved
equipment that would improve efficiency and better provide the specified
qualities of lightness, compactness, strong construction, efficiency
of performance under forest conditions, simple design and low cost.
Only standard parts were used so that there is nothing new about
the equipment except its design and assembly. In each alteration
of design greater simplicity was sought. Every dispensable part
was eliminated to reduce weight.
By the summer of 1930, Beatty had developed two sets: a semi-portable
radio-phone weighing approximately 80 pounds (including batteries
and antenna) and a portable set weighing less than 20 pounds. The
antennas employed with both types were the same. It was a counterpoise
system consisting of an antenna wire stretched approximately 15
feet from the ground between two light masts and a counterpoise
wire at 3 1/2 feet, stretched parallel to the antenna wire. The
length of the system varied from 73 to 90 meters, according to the
frequency in use.
Bottom View of the Two Ranger Units
Figure 5a - The underneath view of the sub-panel of the
Figure 5b - The same view of the portable unit which
may be carried on the ranger's back
The Power-Feed Antenna
Figure 4. This antenna was developed for the special
use of the forest service radio-phone.
Both sets were given extensive field tests in 1930 in the Columbia
forest in southern Washington. Seven of the portables were placed
in service with road and trail crews and fire patrolmen, and were
used throughout the summer. Two of them were used at the Dog Mountain
fire, where a large number of messages were exchanged during the
course of the fire. Although these sets were used by men inexperienced
in radio and without training in the use of code, the records of
the use of the seven instruments showed better than 94 percent successful
performance. The 6 percent failures were due, almost entirely, to
In spite of this good record there were still many problems to
be worked out before the equipment could be voted a success under
all conditions. The bugbear of absorption and shadows had been largely
overcome, but the equipment was too heavy and the aerial too cumbersome.
Therefore, when Beatty dropped the work in early 1931 there was
grave danger that it would be discontinued. It was rescued from
the discard by F. V. Horton, assistant regional forester of Portland,
who put A. Gael Simson in charge of the work.
Simson was employed in forest research but he was an amateur
radio enthusiast, having served as a radio operator in the Navy
during the World War. He was given two assistants, Harold K. Lawson,
a young logging engineer who was employed on timber sales work and
road building, and W. F. Squibb, a student of electrical engineering
at Washington State College, who accepted short-term summer employment
as a ranger guard. All of these men are amateur radio fans. They
took up the job where Beatty left it and tackled the unsolved problems
with that intense enthusiasm that only an amateur knows. Three months
after they started work, I happened in at headquarters one Sunday
morning and finding the whole crew hard at work I remarked to Simson:
"Your assistants seem to be pretty much interested in their job."
"To a fault," he replied tersely, "Lawson, there, is a logging engineer.
He thinks the right time to begin the day is 7 a.m., but Squib is
a student; he likes to work at night and is ready to call it a day
about midnight, and between the two they work me a mighty long shift."
So the testing, experimenting, and rebuilding went on, almost feverishly,
throughout the summer. Both sets shriveled in size and weight and
increased in reliable performance. Perhaps the most outstanding
improvement, however, was in the antenna.
The counterpoise system was unsatisfactory because it is clumsy
and unhandy to erect. The two wires must be taut, parallel and reasonably
level. On rough ground or in dense undergrowth, finding a suitable
place to erect it frequently presented a serious problem. An opening
may be readily found where a single antenna wire can be stretched
where it is quite impossible to find one where two wires could be
stretched 12 feet apart in the clear. It was, therefore, decided
to make a special effort to develop a single-wire system and the
result is a power-feed antenna of very simple design (See Figure
4). The length of the antenna is made to correspond to the frequency
of the transmitter. A loading coil, fitted with a terminal attachment
for the feeder wire, is inserted at the correct point to give the
best results. This point has been found to be about 14 percent.
"off-center." The coil reduced the length of the antenna to about
70 feet, which greatly simplifies its erection. Since the point
of attachment of the feeder wire is definitely fixed by the terminal
post on the coil, no particular care in erecting the power-feed
antenna is necessary, excepting to be sure it is in-the-clear of
branches or other interference. It has the additional advantage
of being several pounds lighter than the counterpoise system, which
is an important contribution to the success of the project.
The innumerable field tests of the past year have brought a great
deal of new information about the selection of a site for the set-up.
It was found, for instance, that a shift of 200 yards from the base
of an overshadowing ridge may increase the strength of the signals
as much as two points in a scale of ten, of which seven points represent
the normal degree of loudness that the receiving operator desires
from a headphone clamped to his ears. Another subject of inquiry
was how readily inexperienced men could be expected to become proficient
in the use of the C.W. portable set. Many of the men who may have
occasion to use it will be temporary laborers, for whom no preliminary
training in sending code is possible. It is really remarkable how
quickly untrained men, who may never before have seen a telegraph
key used, can pick up the use of the code. A monitor is built into
the receiver which permits the operator to hear his own signals.
This steadies his sending and provides a constant check on its quality.
With a surprisingly small amount of practice he can send intelligible
code signals with the tiny telegraph key. As a final demonstration
test, a young laborer employed on trail construction was given about
30 minutes coaching and was instructed to send a dictated message.
In 46 minutes he set up the radio, coded the message, sent it to
a distant station, had it repeated back to him by voice, and packed
up the radio ready for transportation. This demonstration silenced
all doubts whether the rank and file of officers and temporary employees
would or would not be able to use the C.W. sets without long preliminary
Figure 2 - Smoke Chaser with Portable Set
is recording back to field headquarters an incipient fire
by means of the portable set for field use
If light weight is the first essential, sturdy construction is
a second requisite of almost equal importance. The vibrations, knocks,
and jolts of transportation by truck, pack-horse or man-pack would
quickly disable the delicate meters which are usually considered
indispensable in a radio transmitter. All delicate parts and fragile
wiring had to be eliminated to insure dependable performance of
the equipment when it reaches the field. It was found possible to
dispense with all meters (except a small voltmeter which can be
successfully cushioned in sponge rubber). The simple arrangement
of the parts, to reduce wiring and strength of all connections,
were worked out with great care (See Figure 5), and the tubes are
set in spring sockets and cushioned with sponge rubber (See Figure
6) so that they need not be removed during transportation. Both
sets have been subjected to every kind of stress they may meet with
in field use and have stood up under the roughest kind of treatment.
Finally the designers decided to give the semi-portable radiophone
an accident test, just to see how much it would stand and where
failure might first be expected. Four of the six tubes were tied
to their sockets with rubber, the remaining tubes were left free.
The set was then dropped 14 feet to the ground! The jolt caused
the two free tubes to jump from their sockets and to break. The
broken glass was shaken out of the set, the two broken tubes replaced
and it was put "on-the-air" without further adjustment and a conversation
carried on with a station 60 miles away. The sets have certainly
been built for rough going!
The experimental stage is now completed. Every conceivable test
for weaknesses that might develop has been made and as weak points
have developed changes were made to remedy them. Radio is now ready
for the field, the forests, and a thousand ranger officers are reaching
for it. Approximately 150 sets will be available this year, and
these will be issued to a few forests where the need for them seems
most urgent and where good opportunity exists for exacting field
tryouts. It is to be expected that some failures may develop, for
the sets will be used in every kind of climatic situation from the
humid forests of northern Washington to dry deserts of Arizona and
California, from sea level to the timberline country of the Continental
Divide, in heat and cold and from mountain top to the bottom of
deep canyons. Some situations may be found where special equipment
or change of design will be necessary, but the versatility they
have already displayed in experimental tests gives confidence in
their adaptability to almost any situation. Long before sufficient
equipment to supply all of the forests can be had, there will be
opportunity to discover any peculiar situations where special adaptations
will be necessary.
A problem which can be foreseen, but upon which no work has as
yet been done, is regulation of traffic in the channels assigned
to the Forest Service. When 147 forests are equipped with radiophones
and each forest has several central-camp stations receiving reports
from several individuals using portable sets, it can be foreseen
that, without regulation, there might be chaos. The very-low power
and range of the instruments will help to hold this situation in
check to some extent, but some additional regulation will doubtless
be necessary so that all the men will not try to talk at once.
* Forest Service, U.S. Department of Agriculture.
Posted July 4, 2014