this is the text from a web page i found recently...
http://www.mbay.net/~wb6nvh/Motadata.htm

if you follow the above link, it even shows radio pictures.....

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 versio 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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