July 1933 Radio-Craft
[Table
of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Craft,
published 1929 - 1953. All copyrights are hereby acknowledged.
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This Radio Service Data Sheet for
the Motovox Models 10A All-Electric and 10E Battery-Operated "Moto-Tetradynes" is
an example of the dozens of similar schematic and alignment instruction sheets that
have been posted on RF Cafe over the years. Obtaining technical information on most
things, even readily available items, prior to the Internet era was often very difficult
- if not impossible. Service centers had what was need provided by manufacturers
and distributors, but if you wanted to find a part number or service data on a refrigerator,
radio, lawn mower, garage door opener, etc., and did not have the original paperwork,
you were usually out of luck. Nowadays a Web search will quite often get you what
you need thanks to people (like me) who go to the trouble of making the information
available. The stuff doesn't just magically appear or get posted by benevolent governmental
entities. You're welcome.
Motovox Models 10A All-Electric and 10E Battery-Operated "Moto-Tetradynes" Radio
Service Data Sheet
The model 10A car-radio set is a superheterodyne; the model 10E receiver is a
T.R.F. set incorporating a manual sensitivity control; both instruments include
A.V.C.)

Latest in the car-radio line of receivers developed by Motormeter Gauge &
Equipment Corp. are the Motovox All-Electric model 10A, and the Battery-Operated
model 10E.
The model 10A 5·tube set installation includes the following items: chassis,
remote tuning control, reproducer and harness, antenna lead-in, filter bypass condensers,
suppressors "B" unit and harness; a superheterodyne circuit is utilized.
The model 10E 5-tube receiver includes the following equipment: chassis, remote
tuning control, reproducer and harness, antenna lead-in, filter bypass condensers,
suppressors; a T.R.F. circuit is used.
Model 10A
*Measured to ground·; **to cathode. Readings taken with a 1,000-ohms-per-volt
meter; "no signal" setting of set. Total drain, 31 ma.
Model 10E
*Measured to ground; **measured to cathode. Use a high-resistance meter. Drain,
19 ma.
Sensitivity of models 10A and 10E, 3/4-microvolt-per-meter; power output, 2.25
w.
Since the intensity of signal strength delivered by the antenna to the receiver
is directly proportional to the height and effective length and inversely proportional
to the resistance of the antenna, it is necessary to use every precaution to obtain
an effective auto-radio antenna installation. Thus, only a low-capacity shielded
lead-in should be used; also, the antenna should not come closer than 3 ins. to
any metal-work. A counterpoise antenna is used in an automobile since no actual
ground is available. The height of the antenna is, therefore, equal to the distance
between the flat plane of the antenna and the body of the car. Consequently, the
most efficient aerial is one in which the capacity of lead-in and aerial matches
the antenna stage of the receiver, covers the largest possible area and is as far
removed as possible from the body of the car.
The following instructions pertain to the installation of the model 10A set.
After mounting the power supply, run the separately shielded red lead, in the reproducer,
to terminal No.3. Next, connect the red lead in the radio cable to the "B+" terminal
in the supply and the yellow lead to the "B-" terminal, making certain that the
shield of the cable is anchored by the mounting clamp provided in the power supply.
Now connect the black, yellow-tracer lead of the tuning control along with the yellow
lead from the power supply terminal No. 2 to the ungrounded or "hot" post of the
battery. Connect the black lead from terminal No. 1 of the power supply to the grounded
battery post. Make certain that the connecting to the battery are correct. Do not
pull forward the switch underneath the tuning control until the receiver has been
plugged into the harness, otherwise, the power unit win be operating without a load.
Installation instructions which apply to the model 10E receiver are as follows.
Connect the yellow lead in the "B" harness to the negative tap of the 180 V. battery
(four Burgess type 2308 batteries). Next, connect the maroon lead to the"+45" tap,
and the red lead to the "+180" tap. In this line is a 1/4-A. fuse.
The sensitivity control on the model 10E set is located in the bottom of the
receiver. After tuning the set to a no-signal position near 1,400 kc., turn the
sensitivity control right, or clockwise, to "stop," then back it, counterclockwise,
until the static level becomes very high. This is the point of maximum sensitivity.
to exceed this will result in lack of sensitivity and A.V.C. It is recommended that
this control be set just below maximum sensitivity to reduce engine interference.
Due to the current interest in automotive radio installations the following information
concerning car antennas is furnished through courtesy of Motometer Gauge & Equipment
Co. Although most of the late car models are equipped at the factory with an aerial
of some type, earlier cars will usually require the services of a technician acquainted
both with the technique of handling car upholstery and the demands of good antenna
design.
It is recommended that No. 14 or No. 16 mesh copper or galvanized screen be used.
Do not forget to clear the dome-light by 3 ins. In fastening the lead-in to the
screen, a No. 18 insulated wire should be used and if the aerial is copper screen
it should be soldered around two adjacent sides so that a good electrical connection
is assured. The screen should then be securely tacked at all points possible, making
certain that it is not grounded to any metal part of the top. Conceal the lead-in
and replace the top, soldering the end of the No. 18 wire to the short shielded
lead-in which is provided with most sets, making sure to insulate the soldered joint
well; ground the shield to some part of the metal body. Keep the unshielded portion
of the lead-in, that is, the No. 18 rubber covered wire, as short as possible so
that the shielded lead-in actually enters, if possible, the metal corner post. eliminating
the possibility of spark pick-up by the unshielded lead.
Top construction may be divided into the following general classifications:
Open and Convertible. Loosen the top slightly preliminary to putting it back
and weave a No. 18 insulated wire around the border between the top and the flap,
giving in all a total length of about 60 ft. of wire. Then bring down the lead-in
in the manner described above, and re-tighten the top.
Screen Wire Tops. Clip a 3 in. border around the top. Lace the center screen
to the edges, using raw-hide,
Standard Fabric Tops. This type of top will be found most frequently. Use a wire
screen, as described, removing it 3 ins. from all metals.
[references/general/radio-service-data-sheets.htm]
Posted August 7, 2015
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