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
Having never owned a diesel-powered car or truck, I can't say whether
not having a high tension (voltage) ignition system eliminates any
possible interference with AM radio reception. Although not many
people listen to AM radio these days, there was a time when it was
still a popular option along with FM, and a time before that when
it was the only option. Diesels have long been much more prevalent
in Europe, so those of you who were around in the era might recall
whether you were contently listening to the BBC in static-free bliss
while your petrol-powered friends were fighting the ignition noise
battle with chokes, capacitors, and resistor wires. Ignition noise
did not come only from the car you were driving; often in high density
city environments the interference from nearby cars, trucks, and
buses could render acceptable radio reception impossible no matter
how great the noise mitigation in your own vehicle was.
Hints on Design and Installation of Automobile Radio
The rather complex electrical system of the modern automobile
offers many problems for the auto radio installation man. The following
pointers on noise elimination, based on the author's extensive experience
in this field, should prove unusually helpful.
By M. J. Sheedy
In making a radio installation in an automobile it is always
well to look over the car wiring and make certain it is in good
order, also that the breaker points are clean and have a flat surface,
and that the generator brushes and commutator are in good condition.
Courtesy P. R. Mallory
Auto B Eliminator Installation
The relatively small size of the new automobile B eliminators
facilitates installation. This view shows seven available
locations on a typical car.
Shielding the spark plug wires is not recommended. It is expensive
and the results obtained do not warrant it. Tight shielding adds
considerable capacity to the system. This capacity must be charged
and consequently absorbs energy from the coil. This will be noticeable
by hard starting. In cars equipped with a magneto this rule does
Shielding H. T. Wiring
Rubber covered high tension wires should never be shielded as
corona trouble and leakage will soon be experienced if tight shielding
is used. Where it is necessary to shield a high tension wire, varnished
cambric covered wire should be used. This wire can also be had with
metal shielding already on it.
If the ignition coil or coils are mounted on the car side of
the dash, they should be removed and remounted under the hood. Always
keep the hood down when listening for spark noise in a receiver.
The hood acts as a shield to confine the radiation. If a top antenna
is used, it is a good idea to bypass the wire to the dome and tonneau
lights. This will be necessary if the switch is on the ground side.
Another wrinkle is to lengthen the distributor rotor, so as to shorten
Quite often a noisy condition can be traced to poor suppressors.
While a collection of suppressors of various makes, when tested,
may show a nearly uniformed d.c. resistance, yet their a.c. resistance
may vary greatly. This is caused by either the quality or nature
of the material, or the kind of binder used in it's composition.
The simplest and best way to test them is to notice the color of
the spark. The whiter the spark the more efficient the suppressor.
The more blue in the spark, the more a.c. there is present.
If a motor does not idle properly with suppressors, it may often
be remedied by shortening the gap in the spark plugs. The effect
of the suppressor on the plugs is like increased compression.
The installation and service of auto radio equipment can be most
efficiently handled by automotive electric shops, with the services
of a good radio man. Large service stations of this type, having
drive-in facilities, can supply service for a number of dealers,
and are also in a position to make direct sales to their car service
customers. Customers sent in for radio work are also good prospects
for car service work.
Very few dealers have the facilities to properly do the work
and frequently work an injustice on the customer when they try it.
Curb-stone installations are rarely satisfactory. A few manufacturers
discourage their dealers from attempting it by only guaranteeing
the equipment when it is installed by an authorized service station.
This policy reacts to the dealer's advantage. It relieves him
of the installation problem, and assures the customer of specialized
and intelligent service and gives the dealer greater confidence
to make sales. Poor installations have spoiled more sales than poor
Every radio dealer, car dealer, and automotive service station
can sell auto radios. It is an excellent sales item for the radio
dealer in the spring and summer months, when the sale of household
receivers is slow.
Auto radio is gradually taking a prominent place in the radio
industry. Practically all the leading manufacturers are now marketing
receivers for this purpose. Although auto radio was originally introduced
for pleasure cars, it's field is rapidly expanding, and there are
unlimited opportunities for this business.
The thousands of buses in use throughout the country in themselves
constitute a sizable market. Anyone who has ridden any distance
by bus, can appreciate this. A little entertainment or current news
flashes go a long way to break the monotony of an otherwise tedious
ride. Very little effort has been made, however, to sell this market.
We will admit that the general run of equipment has not been up
to standard for this type of service. With the introduction of superhetrodyne
receivers, special tubes, greater output with less current drain,
and dynomotors for plate current supply, this business can now be
gone after with greater confidence. Buses equipped with radio are
given preference by the public and are also in demand (or private
Taxicabs constitute another prospective market. Such installations
can be arranged so that the set can only be used when a fare is
in the car. Much more headway has been made in Europe along this
line than in this country.
If a radio is appropriate in an automobile, it certainly is at
home in a motor boat. Household receivers are not adaptable to this
use and do not give consistent service when used aboard ship. Automobile
receivers are better able to stand the rigors of this type of service.
The one drawback is that while present-day radios are fine for speed
boats, and runabouts, they are not quite adaptable for the small
cruisers, due to the mounting arrangements and types of control
used. The small cruiser constitutes the greatest market.
There is an opportunity for some enterprising manufacturer to
market a set to fill this need. Such receivers should be similar
in type to the present-day midgets, but built to withstand the corrosive
effects of salt air and dampness. Provision should also be made
for additional speakers. Motorboat builders and dealers are waiting
for such a receiver. The radio mariner in coastal waters can set
up a loop antenna with such a receiver and have an excellent direction
Auto radio has made more progress from an engineering standpoint
in the last eighteen months, than in the previous three years of
its history. This is largely due to the cooperation of the accessory
manufacturers in designing special tubes, batteries, generators,
In selling or installing radio sets in cars or boats one should
not overlook the advantages offered by the auto B eliminators, a
number of which have been placed on the market within the past few
months. Equipped with one of these units, the auto radio is as trouble
free as the home receiver. The A battery, of course, requires no
special attention so far as radio is concerned, as that is of necessity
kept in proper operating condition at all times anyway. The extra
drain imposed on it by the radio is slight, but even this can be
compensated for by increasing the charging rate at the car generator.
The use of a B eliminator, depending on the car storage battery
for its supply source, not only eliminates the B battery replacement
nuisance, but most of these eliminators require less than half the
space required for B batteries of the same total voltage. One can
be mounted in any spare space in or beneath the car.
In this connection it is well to make sure before buying any
particular make of eliminator, that it will work with the receiver
which is to be used. Tests have shown that some of the eliminators
on the market are noisy with certain receivers but quite satisfactory
with others. Other eliminators, on the other hand, work satisfactorily,
with any receiver. Some auto receiver manufacturers have tested
various eliminators and are therefore in a position to recommend
the most satisfactory eliminators for use with their equipment.
On the whole, there is now some excellent auto radio equipment on
the market and it is worth looking into. What was yesterday's luxury
is fast becoming tomorrow's necessity.
Posted July 9, 2014