Subject: [NEXTEL-1] MOTOROLA EARLY LAND MOBILE EQUIPMENT INDEX

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Date: Fri, 30 Apr 2004 04:12:14 -0400

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MOTOROLA EARLY LAND MOBILE EQUIPMENT INDEX, 1938-1946

This page is an index to the earliest Motorola police radio
equipment. It is not intended as an all-inclusive history of
early land mobile radio or of the Motorola Corporation itself.

The Galvin Manufacturing Corporation began producing
"Motorola" mobile police receivers in 1937,
considerably later than some other manufacturers such as American
Bosch, Link and Philco. Motorola eventually called their receiver
the "Police Cruiser" model, all but the first of which
were model prefixed "P69". Some prototypes are believed
to exist from late 1936 which are not identified on this list.
Also, special production equipment, which carried an
"SP-" suffix, is not listed here. AM medium wave
receivers were still being produced in the mid-1950's, even
though the FCC began granting VHF 30-39 MHz licenses for 2-way AM
systems in 1936 and granted permanent VHF FM licenses on both low
and high VHF bands in late 1945. After World War Two, most
manufacturers abandoned AM equipment other than as replacement
parts for existing systems. No new Police Cruiser models were
introduced after the War, although at least the P69-18 was
available from existing stock through about 1949.

In 1942, Motorola began selling the "Deluxe" line of
equipment, a large rounded-top two piece radio set often referred
to as the "coffin units" or "doghouse sets."
Although primarily an FM product, the Deluxe line apparently was
offered in a VHF AM version with a type number AMR-13(V) for the
receiver and presumably AMT-30(D) for the transmitter, but this
author has never run across any or found production documentation
supporting a "Deluxe" AM transmitter. Information is
solicited ! In approximately 1948, the Galvin Company officially
adopted the name "Motorola, Inc.."

In January 1951, as a replacement for the discontinued Police
Cruiser series, a Unichannel AM medium wave receiver strip was
made available in the new "Research Line" one-piece
radio equipment. It was available as either a stand-alone
receiver (mounted in a "41V" style case or a motorcycle
side-carrier) or combined with an FM Unichannel transmitter strip
in a 10 or 15" mobile case, for those systems still using
medium wave AM for dispatching. No new model AM VHF transmitters
were introduced after the pre-war T69-20A mentioned below, other
than possibly a "Deluxe" Line AM transmitter.

During wartime, military orders caused cessation of production
of civilian radios and several reductions in the production of
police sets. Police orders were still taken, as municipalities
had a wartime priority, however no new models were designed
during this time. Many departments upgraded to "2 way"
capability after December 1941, particularly the smaller cities,
in order to better prepare for civil defense and "wartime
emergency" operations. In 1946, the the War Assets
Administration was in charge of disposal of surplus military
equipment, and provided many large AM medium wave transmitters
(such as the BC-610) to police agencies free of charge. These
were used on medium wave frequencies to communicate with Police
Cruiser type receivers, and their abundance probably slowed the
trend to convert to new VHF and FM equipment by a number of
years. The majority of police agencies in the United States had
vacated the medium wave frequencies by the end of the 1940's,
scrapping their medium wave equipment such as the Police Cruiser
receivers. However, a few large regional and urban systems
continued well into the 1950's with the same frequencies they had
used prior to World War II. For example, the Los Angeles Police
Department continued to use its 1700 and 2300 Kilocycle
dispatching system into the early 1960's !

Galvin also produced a number of base station receivers and
transmitters during the prewar period. That equipment consisted
of 19 inch rack panel receivers, operating on the 30-40 Megacycle
spectrum, AM, Type B19-19, or a (1942 and newer)
"Deluxe" line AMR-13(B) AC powered VHF AM receiver, in
its own case. There was a complete line of rack mounted medium
wave transmitters:

BASE STATION TRANSMITTERS

T19-23A: 25 Watt "Intermediate Frequency"

T19-30L : 50 Watt "Intermediate Frequency"

T19-30H: 50 Watt UHF 30 MHz

T19-31L: 100 Watt "Intermediate Frequency"

T19-31H: 100 Watt "UHF" 30 MHz

T19-32L: 250 Watt "Intermediate Frequency"

T19-32H: 250 Watt "UHF"

T19-33L: 500 Watt "Intermediate Frequency"

T19-33H: 500 Watt "UHF"

Presumably there was a T19-23H "UHF" transmitter,
but I have no sales literature on that model.

RECEIVERS:

Nearly all Galvin receivers prior to WWII were called
"Police Cruisers". They should have a chrome nameplate
on the front of the housing which says "Police Cruiser"
in script, with a red paint background. The word Motorola does
not appear on the exterior of the receiver itself, but is on the
face of the control head in the form of a red painted tin
nameplate. With the exception of the P69-18SP-2 and later SP
models of the P69-18, all Police Cruiser receivers were
originally intended to mount on the automobile firewall, behind
and below the dashboard. Again with the exception of the P69-18
(which uses a "DC" electrical volume control,) the
volume control is located on the receiver itself and is turned
via a two foot "speedometer" style jacketed mechanical
cable which connects to a knob on the control head.
"UHF" model P69-17A could be mounted in the car trunk,
with a long speedometer type control cable running to the volume
control knob under the car's dash.

All Police Cruisers were essentially modified versions of
Motorola's late 1930's AM broadcast car radios (even the
"UHF" models !) The basic frequency range of all Police
Cruisers except the P69-17A is 1500-3000 Kilocycles. The P69-17A
covered 30-40 Megacycles. The earlier Police Cruisers have a
black wrinkle finish, while the last Police Cruisers have a
blue/gray wrinkle finish. The antenna input was designed for
either a conventional broadcast whip or a copper
"screen" antenna inside the car's headliner
("tar" roof sedans), except for the P69-17A
"UHF" receiver, which shared the transmitting
"whip" antenna on the vehicle's rear quarter panel.

Police systems of the time broadcast on two ranges: state
police, counties and highway patrol (and a few large metro areas)
generally broadcast on the 1550-1750 Kilocycle band, while cities
and small towns used the upper band of 2300-2490 Kilocycles. In
most areas, all local agencies other than state police shared the
same frequency. Frequencies were "coordinated" into
geographical zones to minimize interference, but night-time skip
conditions had become a severe problem by 1942. The Fire Radio
Service was not created at the same time as the Police Radio
Service and appeared some years later. At first, it was not
thought necessary to have radios in fire engines ! Those fire
departments which did install radios, did so by licensing them as
mobile police radio stations, and shared the police dispatch
system.

The Models:

All equipment was designed for 6 volt DC
operation only. Polarity was not important. All were powered by
standard 4-pin auto radio vibrators. All models of Police Cruiser
receivers except the P69-14 and the very first Police Cruiser
contain two vibrators; only one is in use at any given time. A
switch which protrudes through the front panel selects either
vibrator. Should one vibrator fail, the officer could reach down
and select the other vibrator, allowing the vehicle to continue
on patrol without the need to return to the station for radio
repairs. The transmitters did not offer this feature, but the
transmitter vibrators were not in use except during a
transmission and were evidently considered more reliable. All P69
Police Cruisers except the P69-14 are single channel.

* "POLICE" and "POLICE CRUISER":
The first police receivers made by Galvin, before the P69 model
series. Essentially a broadcast auto radio with the oscillator
and RF section cut down to receive 1.5-1.7 or 2.1-2.8 Mc/s police
frequencies. Tunable, the control head was identical to a
broadcast auto radio control head except for the frequency range
markings. The case was a rectangular black wrinkle tub, the same
as used by the auto broadcast radios. The first police receiver
appears to have been just called "Police," and was
merely a modified broadcast set. It was almost immediately
updated to the "Police Cruiser," which now featured the
die cast chrome "Police Cruiser" nameplate on front.
All of the tubes were double-ended ST style two-digit glass
types. Discontinued by 1937. No squelch control on the
"Police" set..

Thanks to Ray Grimes of Motorola, Inc. for the above photo

* P69-12: 6 tube "economy model".
Crystal control, single channel. Dual selectable vibrators. Uses
button cell bias batteries in the audio section. Exterior black
wrinkle enamel. 1550-3000 kilocycle range. Appearance nearly
identical to P-69-18. Production dates approximately 1939-42.
(PHOTO TO FOLLOW SOON)

* P69-13: 8 tube "deluxe model".
Crystal control. Exterior black wrinkle enamel. The most common
Cruiser prewar model other than the P-69-12. Dual selectable
vibrators. 1550-3000 kilocycle range. Appearance nearly identical
to P-69-18. Production dates approximately 1939-42. (PHOTO TO
FOLLOW SOON)

* P69-14: 8 tube "pushbutton" 4
channel model. Tunable, no crystal. Channels changed by
electromechanical solenoid stepper system. Single vibrator. Case
elongated and different than other Police Cruiser sets. Control
head involved separate pushbutton channel selection box. This
model believed very rare. Exterior is black wrinkle enamel. There
were at least two different models of P69-14. The model below is
the original version , P69-14. There was also at least a P69-14D,
which featured a rectangular case. Production dates approximately
1939-42.

* P69-17 (P69-17A): 8 tube VHF AM model.
Operated in the 30-40 Megacycle range, crystal control. Single
channel. Exterior black wrinkle enamel. Case style in front is
slightly different from others; holes for alignment points are
present a large handle is mounted on the front panel (evidently
it was thought this new "UHF" set would need more
frequent service !) Used then-new 1853 (6AB7) VHF tube as RF
amplifier. Intended as the companion to the T69-20A VHF AM
transmitter in all "UHF" 2-way systems. The Motorola
P-374-A control head physical appearance is unknown; it is
similar to other Cruiser heads but has a squelch on/off switch
and mechanical volume control knob. Many units were apparently
supplied with the same control head as the medium wave
"intermediate frequency" Police Cruisers, which did not
feature a squelch switch. The P69-17 was typically trunk-mounted,
in contrast to medium wave receivers, and shared the transmitting
antenna via a T/R relay. Production dates approximately 1940-49.

* P69-18: 8 tube final version of Police
Cruiser, probably 1942 or later introduction. Crystal control,
single channel. Selectable dual vibrators. Exterior blue-gray
wrinkle enamel. Volume control is a DC remotely controlled
design. Control head is the P-8022 as used on wartime and postwar
FM sets. The squelch control is located on chassis of receiver,
but several -SP modifications allow the P-8022 control head to
also control squelch. -SP1 Modification allowed remote squelch
control. -SP2 modification allows trunk mounting of P-69-18 and
cabling interface to standard FMTR series cable set and FMTR-30D
transmitter plus adding the -SP1 modification. Production dates
approximately 1943-50. It is believed that most were produced in
the 1945-49 era.

* No P-69-15 or P-69-16 sets are believed to have been
manufactured.

RECEIVER CONTROL HEADS:

Shown below are the speedometer cable style "remote"
control head for the Police Cruiser receivers which did not
feature electrical volume control, and the "small"
mobile speaker. There was also a "large" mobile
speaker, featured in the photo of the transmitter installation
shown later on this page.

MOBILE TRANSMITTERS:

The AM mobile transmitter was the T69-20A. This appears to
have been Motorola's only AM mobile transmitter, and is a two
piece set in which the power supply and modulator are in one case
and the RF section in a second. As originally configured, the
power supply was usually installed on the firewall of the
automobile, next to the receiver and under the glove box, while
the RF section was located in the trunk and attached to its
antenna via a short braided copper rope. A fat cable delivered
the high voltage and other lines back to the trunk, under the
floor mat. However, placing both sections in the vehicle trunk
was a popular option.

Exterior color of the units is blue-gray wrinkle enamel, with
color shades varying substantially over the years of production,
as the photos below show. It is believed the T69-20A first began
to be sold in late 1939; production continued through at least
1949. The control head was available as a "handset"
type, in which a push to talk Western Electric "E"
series telephone handset hung alongside or on a cradle on top of
the control box, which was a gray square box with Amphenol
connectors on the bottom for the control cable connections. Later
versions featured a Western Electric "F" series
handset, as shown below. A microphone type control box was
alternately available; this is believed to have been the same
control box, but without the handset cradle. The control head
only controlled the transmitter; the receiver retained its own
control head . See typical T69-20A installation photo below:

"SPECIALS":

Various special production radios were
produced. One such example is the curious pack-set
transmitter-receiver appearing below, which is shown in a circa
1941 Motorola catalog. It is believed this unit was essentially a
prototype which led to the postwar FPTR - and FHTR- series pack
sets. Probably few (if any ?) were actually sold.

"ONE PIECE SETS":

During wartime and to the end of Police Cruiser production, a
kind of "one-piece" two-way radio set was manufactured,
which consisted of both T69-20A transmitter cases and a P69-18 or
-17 Police Cruiser receiver, all mounted on a large copper plated
chassis, which was mounted in the trunk compartment of a police
car or in a utility compartment on a fire engine. The later
versions of these sets used the P-8022 control head for both
receiver and transmitter functions. They were purchased by the US
Government in some quantity. For example, they were used in the
trunks of Signal Corps staff cars for the 1940 annual War Games
at Camp McCoy, Sparta, Wisconsin (believed to be P69-17A/T69-20A
combinations.) Advertisements in CQ Magazine in the late 1940's
by surplus dealers offered them as having come from
"military police service."

The P-8022 control head above was often used with the
"one piece" installation shown above it, but not with
the original T69-20A installations, which used separate control
heads for transmitter and receiver. Also note that coiled
microphone cords are a postwar development. The original
microphone used with the above control head would have had a
straight cord, and would have had a more flush-appearing,
"push up to talk" button which identified the earliest
Shure Mfg. Corp. mobile microphones used by Motorola. In
addition, the rear "hangup button" was a wartime
development; prewar mikes would have had a hang-up ring on the
top. As an aside, the above control head, last produced in 1950,
was used by the Los Angeles Police Department from 1949-58 !

NOTE REGARDING CAR-TO-CAR OPERATION: Readers
may wonder how radio equipped cars communicated with each other
directly using medium frequency receivers and VHF AM
transmitters. Normally, they couldn't ! However, there was an
interconnect function available at the base station, which
allowed the audio from the base station receiver to be fed into
the microphone line of the base station transmitter, and the base
station would be left on the air continuously as long as this
switch was closed. This function, often called the "hot
button," allowed cars to communicate with each other in
emergencies, such as coordinating chases and so forth. Of course,
mobile units with microphones instead of handsets would need to
reduce the receiver volume to prevent feedback, as such a system
was "full duplex."

MIX AND MATCH: It was not
uncommon to find Motorola receivers or transmitters matched up
with competitive makes of equipment. For example, some agencies
might have started out with Philco mobile police receivers, and
then added Motorola T69-20A transmitters. Or, a Galvin Police
Cruiser receiver installation might have had a Stancor or GE
transmitter added later. Some of the earliest postwar 2-way
California Highway Patrol installations started out with a Police
Cruiser receiver, and added both Motorola and RCA 39 Megacycle
VHF FM transmitters later on, in the case of the RCA by modifying
the RCA control head to operate the P69-18 Motorola receiver !

THE ANTENNAS:

In Police Cruiser receive only installations (1
way radio), the antenna used was a regular broadcast whip. Other
options included the "screen" antenna and an extra
length "super" broadcast whip. The "screen"
antenna was only used in cars of the 1920's and early 1930's,
which still had a roof made of a tarred fabric material rather
than a full steel roof. A copper or bronze screen was inserted
between the "tar" top and the wooden slats of the roof,
and the lead-in brought down to the receiver through the hollow
post on one side of the windshield. The "screen"
antenna was far superior to all other types, but disappeared into
history when cars began being manufactured with all metal roofs.
There were other antenna designs, which were unsuccessful, such
as a trombone shaped affair which mounted under the auto running
board on the driver's side, on insulated spacers, or the front
bumper being used as an antenna by completely rubber-insulating
it from the rest of the auto chassis. Although outside the scope
of this web page, motorcycles did make use of the screen antenna
to some extent. Old photos show the screen, about the size of a
ping-pong paddle, mounted horizontally on insulators above the
rear fender.

In two-way installations, a separate antenna
was used for the transmitter. Motorola's antenna was the strange
three-legged affair as shown in the above photograph of a T69-20A
in a police car, which featured an adjustable length whip. The
one-piece set shown above included a transmit-receive antenna
relay, in a small box, such that the only antenna necessary would
be the transmitting antenna on the rear of the patrol car.

THE FM EQUIPMENT:

FM was first used in 1940 by the Connecticut
State Police radio system, with equipment built and designed by
Fred M. Link Radio Co. in connection with Professor Daniel Noble,
consultant. Noble would shortly thereafter joing Galvin in direct
competition with Link. It can be seen that it was no accident
that the Motorola FM equipment bore a close resemblance to the
Link designs !

Galvin brought out its own line of FM police
equipment in approximately 1941. FM was not an immediate success,
and initially few units were sold. The widespread success of VHF
FM in armored units during the war proved its superiority in
mobile operation, and the men who would return from war to work
in and design mobile radio systems had learned its advantages.
There was widespread conversion to FM and "UHF" at the
end of the War, when the FCC made permanent allocations of 30-40
and 118 Megacycle range frequencies to police and emergency radio
systems.

Motorola's FM equipment was called the
"Deluxe" line, although they appear to have thought up
that name sometime after the equipment was being marketed. The
Deluxe line was a superb piece of equipment for its day, reliable
and offering high performance. It outperformed the AM equipment
to a significant degree in both range and clarity, and
represented Motorola's primary product line after the War. Once
production of the FM equipment was in progress, Motorola ceased
promotion of AM equipment although it was still produced and
available for purchase for another ten years. Shown below is the
first Deluxe line equipment to be offered; the FMR-13(V) 30-40
Megacycle FM receiver is on the right, the FMT-30(D) 25 Watt
30-40 Megacycle FM transmitter on the left, and the P-8022
standard control head in front. The Deluxe line went through a
number of improvements, which will be detailed in a separate web
page covering Motorola postwar and 1950's equipment.

----------------------------------------------------------------------------------------------------

This page is maintained and updated by Geoff Fors, WB6NVH, in
Monterey California USA. It is intended to convey historical
information rather than be a masterpiece of web design ! It is a
private effort not sponsored by Motorola.

If you have or are looking for old police radio information,
printed materials, equipment, parts, photos, etc. I would like to
talk to you ! Any submissions can be added to this and other web
pages I am creating. You can contact me via e-mail by manually
entering my address as wb6nvh @mbay.net . I had to remove the
auto-link to my e-mail address, due to excessive SPAM. By regular
mail: Geoff Fors, PO Box 342, Monterey California 93942. If you
are interested in old land mobile technology, contact me - - I am
starting an internet special interest group to share resources,
equipment and knowledge.

Thanks to Ray Grimes of Motorola, Inc. for some of the
black & white brochure photos

Be sure to check my other web-pages, such as the California
Highway Patrol Radio pages at http://www.mbay.net/~wb6nvh/chpradio.htm

http://www.mbay.net/~wb6nvh/CHP2001.htm

Ver. 2/06/2002 Copyright 2000 All Rights Reserved

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