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 nor 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, RCA, Link and Philco. At the time, police dispatching was almost exclusively in the 1550-1750 Kilocycle and 2300-2490 Kilocycle ranges, and was of course AM. Motorola eventually settled on the name "Police Cruiser" for their first police receivers, all but the first of which were model prefixed "P69", the initial offering being called only "Police." 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 into the mid-1950's, even though the FCC began granting VHF 30-39 MHz licenses for 2-way systems in 1936 and granted permanent VHF 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 1951. The FCC issued an order after WWII directing that all new license applications for land mobile radio services were to be issued 150 MHz allocations, absent a compelling reason requiring low band or medium wave frequencies.
In late 1940, Motorola began selling the "Deluxe" line of equipment, a large rounded-top two piece radio set often referred to as "coffin units," "doghouse sets," or "double humpers." 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 nor 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 for the new "Research Line" one-piece radio equipment. It was available as either a stand-alone receiver (mounted in a "41V" style case or in 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 the "Deluxe" Line AM transmitter suggested above.
During wartime, military orders caused cessation of production of civilian radios and reduction 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 except for 118 Megacycle versions of the "Deluxe" line equipment (used by the City of Miami, Florida in mobile and base configurations, and by the California Highway Patrol as mountaintop mobile relays.) 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 Hallicrafters 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 1730 Kilocycle AM dispatching system until 1965!
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 B-19-19, 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 and "UHF" transmitters, the medium wave being referred to as "Intermediate Frequency":
BASE STATION TRANSMITTERS
Presumably there was a T19-23H "UHF" transmitter, but I have no sales literature on that model.
BASE STATION RECEIVERS
MOBILE 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 painted background. The word Motorola does not otherwise 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 P-69-18SP-2, all Police Cruiser receivers were originally intended to mount on the automobile firewall, behind and below the dashboard. Again, with the exception of the "SP-1 and SP-2 versions of the P-69-18 (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 P-69-17A could also be mounted in the car trunk, but with a 20 foot 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 !) and all are AM receivers. The basic frequency range of all Police Cruisers (except the P-69-17 and 17A) is 1500-3000 Kilocycles. The P-69-17 series covered 30-40 Megacycles. The earlier Police Cruisers generally have a black wrinkle finish, while the late war and postwar 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 ("tarred fabric roof" sedans), except for the P-69-17 "UHF" receiver, which shared the transmitting "whip" antenna on the vehicle's rear quarter panel and thus required a separate T/R relay.
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 other band of 2300-2490 Kilocycles. In many areas, all local agencies other than state police shared the same frequency, which was often the one also used by the Highway Patrol, and thus there were small towns with systems on frequencies technically reserved for state police use. Frequencies were "coordinated" into geographic zones to minimize interference, but night-time skip conditions had become a severe problem by 1940. 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. There were some special production sets made for 24 and 12 Volt systems, primarily for large fire engines and trucks. Polarity was not important, although the majority of patrol cars were positive ground. All were powered by standard 4-pin auto radio vibrators. All models of Police Cruiser receivers except the P-69-14 and the very first Police Cruiser contain two vibrators; but only one is in use at any given time. A switch which protrudes through the front panel selects the 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. It is a common mistake to assume the 1-2 switch on the face of the housing refers to channels, but it refers to the vibrator in use! 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 P-69 Police Cruisers except the P-69-14 are crystal control, single channel. Particularly aggravating for the collector and historian is that no P-69 model numbers appear clearly or regularly on the equipment other than an apparent two digit number stamped on the lower housing shell, which was easily separated from the receiver, and on the paper tag which is glued inside the lid to show parts layout. Postwar receivers generally have ink stamped dates underneath the chassis and some of the P-69-18's contain an inked-stamped model number. The following list consists of models known to the author. There are almost certainly more.
* "POLICE" and "POLICE CRUISER": The first police receivers made by Galvin in 1937-38, before the P-69 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." 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 1938. No squelch control on the "Police" set. Rare.
Thanks to Ray Grimes of Motorola, Inc. for the above photo
* P-69-12: 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 quite similar to P-69-18. Production dates approximately 1939-42. Uncommon.
* P-69-13: 8 tube "deluxe model". Crystal control. Dual selectable vibrators. 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. Common.
* P-69-14: 6 tube tunable non-crystal model. Used with the 6-pushbutton control box shown in photo below. Case same as other Police Cruiser models. Single vibrator. Examples seen have had gray wrinkle painted cases. Used extensively by California Highway Patrol, 1938-50. The pushbutton shown on the lower left of the radio housing is referred to as the "tone control pushbutton." There was no squelch circuit on the P69-14. Rare.
Photo courtesy Daniel Noble, Motorola Inc.
* P-69-14A through P-69-14B: No information is available on how these vary from the original P69-14, or whether there actually were P69-14A or B models, but as there was a "C" model, presumably there were.
* P69-14C: The P-69-14C featured seven single-ended octal tubes (only six tubes in the original P69-14,) included squelch, and did not feature the "tone control" of the P69-14. Otherwise essentially the same as the P-69-14. Rare.
* P-69-14D: 8 tube "pushbutton" 4 channel model. Tunable, no crystal. Improved version of P-69-14C, using single ended octal based tubes. Elongated case, shape is different from the other P-69-14's. Channels still changed by electromechanical solenoid stepper system. Single vibrator. Color finish is believed to have been gray wrinkle. Control head involved separate pushbutton channel selection box. This model believed very rare. . Production dates approximately 1938-42. The solenoid channel selector system was reported to have been unreliable. This model appears to have competed with a similar set manufactured by RCA, which was used by the FBI and federal agents. Rare.
* P-69-17 (P-69-17A): 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 T-69-20A 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. The P-69-17A is essentially the same as the P-69-17 other than a redesigned squelch circuit. The P-69-17 was often trunk-mounted, in contrast to medium wave receivers, and shared the transmitting antenna via a T/R relay. Production dates approximately 1941-49. Somewhat rare. These were used primarily by small cities which did not need long range or inter-operability with state and county systems. The P-69-17 is not particularly sensitive and with the low power of the companion T69-20A transmitter, range would have been somewhat less than that of a modern CB radio. Common.
* P-69-18: 8 Tube Medium wave receiver, the final and last generation Police Cruiser. Late 1940 is believed to be introduction date. Crystal control, dual vibrators. Most are in a black wrinkle painted tub although color was changed to blue-gray late in war years or immediately thereafter. Control head same as P-69-13 series. Circuitry similar if not almost identical to P-69-13 series. Produced at least through 1948. Somewhat common.
* P-69-18 SP-1 and SP-2 : Probably 1942 or later-dated modified P-69-18. Crystal control, single channel. Selectable dual vibrators. Exterior blue-gray wrinkle enamel. Both of these modifications remote-wired the volume and squelch controls so that they would be controlled at the separate control head, electrically. The volume control was then a DC remotely controlled design rather than the speedometer style cable of earlier models. Control head is the P-8022 as used on wartime and postwar FM sets. The -SP2 modification includes the -SP1 modification and also allows trunk mounting of P-69-18 by adding a cable connector box (see photo below) which matches a standard FMTR series cable set and FMTR-30D transmitter. The -SP1 modification used a small round connector on a short pigtail lead to electrically remote the volume and squelch controls. The -SP2 used pin-tip plugs which attach to the cable connector box (or directly to the control head if it is mounted within a short distance of the receiver.) Production dates approximately 1943-51. It is believed that most were produced in the 1945-49 era. Common.
* No P-69-15 or P-69-16 sets are believed to have been manufactured. It is also believed that assorted special versions were made to customer order, such as non-standard power supply inputs, mounting schemes and so forth.
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, such as the P-69-13, 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 first Motorola AM mobile transmitter was the T-69-20A. If there was a non-"A" model, it must have been a prototype. 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 rather thick 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.
This transmitter operates in the 30-40 Megacycle range, using an 807 power amplifier tube modulated by a 6N7. It is crystal controlled on a single frequency and outputs approximately 10 Watts. The power supply is a 6 volt type.
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 T-69-20A was first 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, simply missing the handset cradle. The control head only controlled the transmitter; the receiver retained its own control head . There were at least two variations of T-69-20A control head style. 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 T-69-20A transmitter cases and a P-69-18 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 P-69-17A/T-69-20A combinations.) Advertisements in CQ Magazine in the late 1940's by surplus dealers offered these as having come from "military police service." There were several varieties of steel platforms used to mount these "one piece" sets. One platform only mounted a T-69-20A transmitter and power supply in the trunk, without a receiver (which was still dash mounted.) The original platforms contained legs to allow them to be suspended in the auto trunk, next to or above the spare tire. Few platforms have survived.
The one piece set shown here was used by the Tracy, California Fire Department in a fire engine and was licensed as a police transmitter.
The P-8022 control head above was often used with the "one piece" installation shown above it, but not with the original T-69-20A installations, which used separate control heads for transmitter and receiver. This control head was primarily used with the "Deluxe" line of FM equipment, introduced in 1940. 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 "hang-up button" was a wartime development. Prewar mikes would have had a hang-up ring on the top instead. As an aside, the above control head, last produced in 1950, was still in use by the Los Angeles Police Department in 1959, operating a custom made mobile radio with a low frequency AM receiver and a VHF transmitter.
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. This was particularly true during the war years when it was difficult to source equipment and limited money to do so. For example, some agencies might have started out with Philco mobile police receivers, and then added Motorola T-69-20A 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, in the case of the RCA by modifying the RCA control head to operate the P-69-18 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 (called "turret top" cars.) . 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 a strange three-legged tripod affair as shown in the above photograph of a T-69-20A in a police car, and 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, as in modern installations. This had the disadvantage that in cases where the receiver was a low frequency type, full duplex operation was no longer possible.
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. under supervision of Professor Daniel Noble, consultant. Noble would shortly thereafter join Galvin (Motorola) 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 ! By the summer of 1940, both GE and Motorola had announced their own lines of FM VHF equipment and several other manufacturers quickly followed.
Galvin had its own line of FM police equipment in production by late 1940, just months after Link and GE had begun making deliveries. FM was not an immediate success, and initially few units were sold. The war emergency on December 7, 1941 curtailed most civilian production. Nonetheless, during the war the development of FM police equipment continued, with some systems such as the Miami, Florida Police and the California Highway Patrol operating 118 Megacycle FM systems (Miami for mobile radios, CHP for mountaintop relays.) The California Highway Patrol began using Motorola FM transmitters in its patrol cars in 1941 on an experimental basis and during the war would buy hundreds of them. 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 150-174 Megacycle range frequencies to police and emergency radio systems and reassigned the 118 Megacycle band to aircraft use.
Motorola's FM equipment was called the
"Deluxe" line, although they appear to have thought up
that name sometime after the equipment was first 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 altogether although it was still being 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.
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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. let me know! 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 always looking for others to share resources, equipment and knowledge. I am looking for other examples of old police radio equipment from the 1930's and 1940's - - don't let this equipment wind up at the landfill!
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
Main California Highway Patrol Radio History Page:
http://www.mbay.net/~wb6nvh/chpradio.htm
Current California Highway Patrol Radio Systems Page:
http://www.mbay.net/~wb6nvh/CHP2001.htm
Regency M100 Scanner Conversion Page:
http://www.mbay.net/~wb6nvh/M100conv.htm
Russian Lavina M HF Portable Transceiver Page:
http://www.mbay.net/~wb6nvh/Lavina.htm
Regency RH256 Mobile Radio Programming Instructions:
http://www.mbay.net/~wb6nvh/RH256.htm
GE / Ericsson S825 Control Head Programming Tutorial:
http://www.mbay.net/~wb6nvh/GES825.htm
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