CALIFORNIA HIGHWAY PATROL

 MOTORCYCLE RADIO SYSTEMS

This page details the police motorcycle radios used by the California Highway Patrol from approximately 1938 to the present.

The first motorcycle radios used by the CHP were one-way, i.e. receive-only, on 1674 Kilocycles AM and were first installed in approximately 1937-38. The entire statewide system dispatched on this one frequency through at least 1950. The CHP's official history states that dispatching changed to VHF in 1950, however it is believed that some or most areas still simulcast on the low frequency AM channel at least through 1952, until all motorcycle and mobile units could be changed over.

THE FIRST ONE-WAY RADIOS, RCA, 1938-50:

These motorcycle receivers were made by RCA and are shown below. They used octal based tubes and were similar to the GE receivers made at the same time, which fit into the Harley Davidson side carrier boxes in the same way. The antenna was a small semi-circular screen suspended over the rear fender on porcelain stand-off insulators, which in appearance looks not unlike a a small tennis racquet without its handle. These were reasonably trouble-free but still required weekly maintenance.

In 1942/43, a number of one way receivers were supplied by the Air Associates Company of Los Angeles to equip motorcycles added since the original RCA purchase and as part of the war emergency.  Air Associates also supplied an experimental two way motorcycle radio for evaluation, some time in the 1940's, however for some reason it was not successful and no further sets were purchased.  Throughout the war and up to 1950, the motorcycles remained primarily one-way other than some evaluation installations and a few Vetric radios purchased in the 1949-52 period.

LINK-VETRIC 2-WAY RADIOS, 1949-52

During the period of approximately 1949-52, the CHP seems to have purchased a small quantity of Vetric motorcycle radios, made by the Vetric Company of Alhambra, California, for evaluation. Sometime in the mid 1940's, Vetric had been purchased and absorbed by Link Radio of New York City, although Link seems to have kept the Vetric plant intact and continued to use the Vetric name on motorcycle radios, as a subsidiary company. The Vetric radios would have been AM receive, on the CHP's 1674 KHz frequency, and FM transmit, on 39.78 MHz. It is believed that not many of the Vetric sets were purchased and that they were removed from service when dispatch switched to VHF FM, although it is possible Link supplied VHF FM receivers to replace the medium wave AM versions. By the early 1950's, Vetric was out of business and the original Link Radio had been sold to other parties. My reference to CHP use of Link-Vetric equipment is a 1949 dated Vetric manual which shows a photo of a CHP motorcycle equipped with a Vetric two way radio.  One of Vetric's largest sales had been to the Los Angeles Police Department, which used an equivalent radio, receiving on AM at 1730 KHz and transmitting FM in the 30 MHz region. These replaced the LAPD's one-way receive-only radios made by CEC Company of Pasadena, California.

THE AVIA TWO-WAY VHF RADIOS, 1951 - 56:

The first two way VHF FM motorcycle sets to be used by the CHP on a large, statewide scale were made by the Avia Corporation of Los Angeles and apparently initially delivered in 1951. Avia was a manufacturer of "photographic equipment" according to its manuals, and it is curious how they got into the police motorcycle radio business. All of the RCA one-way, Link-Vetric and Air Associates sets were taken out of service at that time. However, the Avia radios were regarded as flimsy and a disaster from an engineering and maintenance standpoint, breaking down almost constantly and requiring near daily attention. This is partially due to the construction of early police motorcycles, which had no rear suspension.  Standard periodic maintenance intervals dropped from weeks to days. The Avia design used tubes which suffered from poor socket retention. I have been informed that tubes would pop loose from their sockets and smash themselves under the vibration of motorcycle operation. This must have referred to the unshielded miniature tubes and possibly the 2E26 power amplifier tube. Technician morale suffered terribly from the maintenance headaches the Avia sets created. The Avia control box used a pushbutton switch hidden under the microphone hang-up clamp, which energized the transmitter's tube filaments in order to save battery power. The Avia control box is quite unique in appearance, as shown below (note-knobs are not original) and seems to have been the only postwar American motorcycle radio to feature a weatherproof horn speaker instead of a conventional paper cone type. Note that some Avia control heads were supplied with a black painted speaker while others had a dark silver-gray speaker.  The Avia control head shown below is from the Los Angeles CHP office; note that the metallic foil decal around the knobs is missing.  See the circa 1952 accident scene photo below, where it appears that the decal is also missing on that motorcycle's control head...

Photo below courtesy Gene Rastberger 

Photo above courtesy Rolland Mouser

THE MOTOROLA TWIN-V RADIOS, 1956-64:

Beginning in summer 1956, the Avias were rapidly replaced by the Motorola two-piece M31GGV "Twin-V" motorcycle radio, which was essentially the standard automobile radio chassis separated into two sections, to be mounted in the side saddlebag-box carriers used by motorcycles of the era. The Motorola radio, which used miniature tubes as did the Avia, was very successful and maintenance down-time intervals were reduced to approximately 10 months. The radio was a two channel transmit, single channel receive, carrier squelch 6 volt unit which was rated at 10 Watts transmitter output. Motorola made no attempt to "ruggedize" the receiver and transmitter chassis on these radios, leading one to wonder why the Avia was so despised when the design was all not that different.  Curiously, the "Twin-V" name, which referred to either 6 or 12 volt battery capability, was a misnomer for this radio, which was for 6 volt systems only. This was probably because there were no 12 volt motorcycles in existence and no manufacturer planned to produce any in the near future. These radios still required a relatively large current drain from the battery and could not be left turned on without the engine running for any period exceeding a few minutes, even with the transmitter turned "off."  Dead batteries on motorcycles in service were a  problem for traffic officers during this era.

It is presumed that all, or at least the majority of these radios, were gone by 1966, although there may have been an isolated  few still in service after that date.  

NOTE CONCERNING THE ABOVE PHOTO: The key switch turns power on/off to the radio. The toggle switch is the "standby" switch which turns off the transmitter tube filaments to save battery power during periods when no transmitting is anticipated. The toggle switch is actually located above the key switch, not next to it as in this photo. Evidently Motorola used the photo of an earlier model motorcycle radio housing without anyone catching the difference, which is common in their publications from this era.

Oddly, it appears that sometime after 1956 the CHP began mounting the Twin-V motorcycle radios on the opposite, "backwards" side from the above diagram. In other words, the "wrong" side.  It is not known why, and as the cables then exit on the outside walls of the box, must have been peculiar.  If you have any idea why, please let me know!  I have been told that apparently the Harley Davidson frame system and fork arrangement was changed in the late 1950's, and possibly the only way to make these boxes fit was by reversing the positions.   The small photo below shows such an example, and appears to date from approximately 1959-62. It is erroneously described as a 1964 photo in the AAA magazine in which it recently appeared, which can not be correct since the license plates on the cycles are 1956 series, which were discontinued in 1963. The box shown on top of the fender is a first aid kit and flare storage box.

Photo courtesy AAA of Southern California

Photo below is of an actual CHP control head as removed in 1966.  Note that the knobs, curiously, are black rather than the standard white, and that they have a sort of tension-lock nut on them which is not featured on the normal "Twin-V" era control heads.

THE MOTOROLA "TRANSISTORIZED DISPATCHER RADIOS,"  1958-77:

Some of the" Twin-V" motorcycle radios were experimentally replaced in approximately early 1958 by the new Motorola "Transistorized Dispatcher" hybrid motorcycle radios, a one-piece set which made extensive use of transistors and which was shock-mounted within a hard shell weather housing, usually over the rear fender, rather than in boxes at the saddlebag areas. Those sets were model T31-1-PH50 and were otherwise of the same power level and features as the older Twin-V radios, except for dramatically lower battery power consumption and extremely high reliability. These sets are generally referred to as "Motorcycle Dispatchers."  Officers and technicians were ecstatic with the performance of these radios and squabbles often broke out over seniority as to who was to have the transistorized radio equipped cycles! These first generation Transistorized Dispatchers were slightly different than the ones shown below, in that until approximately late 1959, there was no microphone hang-up assembly on the left side of the control head, and the microphones were the same rounded style as shown on the "Twin-V" vacuum tube radios above.

In approximately March 1960, more of the remaining Twin-V motorcycle radios were replaced by the newer Transistorized Dispatcher sets, model T31AAT-1114A, but all three types remained in service through at least 1963. Motorola began changing model numbers in 1958, hence the different nomenclature.  The fleet of remaining older equipment was converted to "narrow band" operation (5 KHz FM deviation) in 1962-63 and many if not most of the M31GGV "Twin-V" two piece radios were surplused out at that time. The fleet was updated on an almost continuous basis through 1967, starting in April 1962 by the T31BAT-3140A-SP1 version, essentially the same radio but with an all solid state receiver section and now with "Private Line" tone squelch, and in early 1965 CHP took delivery of a quantity of  the T31BAT-3100B-SP3 version as well. The -SP3 version featured two transmit and one receive channels, with "PL" operation.  Unlike the Twin-V radios, the "Dispatcher" series used "instant heating" tubes in the transmitter, which required waiting approximately one to two seconds after pressing the push-to-talk switch on the microphone before the transmitter would be putting out power.

Most of the T31BAT series and the previous Motorola Transistorized Dispatcher models were eventually supplemented by a later and final version, starting in perhaps 1966 or 1967, apparently the last major order for Motorola of this already obsolete equipment.. This last model (Z31BAT, or possibly X31BAT ?) was a special model made specifically for the CHP. The essential difference of this last set compared to the "T31" model was the addition of a 5 position single-tone "burst tone" selector switch and a 4 frequency S-C-S-C "car to station" and "car to car" switch so that the motorcycle radios offered the same features as the car installations. In other words, two receive channels and four transmit channels.  This last Z31BAT was a 12 Volt radio, because Harley Davidson made the changeover to 12 Volts in 1965. The remaining few T31 model radios were eventually converted to 12 volt operation, as the new motorcycles began to be placed in service, and it is believed that all of the 1955 vintage M31GGV "Twin-V" radios were scrapped by 1967.

Note- model number shown in photo below not yet confirmed! 

The photo below shows Telecommunications Technician David Wisniewski in spring of 1979 at the Central Los Angeles CHP office, where some of the TV series "CHiPs" episodes were filmed.  Notice that the motorcycle still has the last generation Transistorized Dispatcher radio mounted, as in the control head photo above. Central Los Angeles was still using the older radios until the motorcycles they were mounted on were retired.

Photo courtesy David Wisniewski, K6GBB

THE MOTOROLA MAXAR RADIOS, 1977- ~1990.

The Transistorized Dispatcher radios were so successful that same basic design remained in main service with the CHP from 1958 until 1977, surely a record for any two way radio. In 1977, they finally began to be replaced by a bizarre custom made Motorola CHP motorcycle radio, which was essentially two "Maxar" dash mount radio chassis stacked one on top of the other, in a sheet metal container which was mounted inside a white fiberglass housing, placed over the motorcycle rear fender. The antenna, as in past models, was mounted separately rather than on the housing itself.  As seems to be the case with any new radio the CHP adopts, many of the older radios continue in service for some years after the introduction of the new equipment.  In this case, some of the Z- series Transistorized Dispatchers mentioned above were still in service well into the early 1980's.  A "mutilated" TV prop example of the Z series Dispatcher control head can be seen in the opening credits of the TV series "CHiPs."

The dual-Maxar chassis radio was the model Q2239A (note non-standard Motorola type number) with the word "Maxar" placed on the serial number plate.

The photo below shows one variation of the control head. At some point after they were in the field,  the microphone hang-up bracket was modified by CHP on many cycles such that the microphone hung up facing the rider, rather than on the left side as in the factory-supplied configuration. At the same time, connections were added for a quick-disconnect jack to facilitate an in-the-helmet microphone and headset. For installations using the in-helmet microphone, a shop-made "transmit" switch was tied to the end of one of the handlebars. This switch was a two position momentary toggle switch, which duplicated the function of the rocker style PTT switch on the standard microphone, with a rubber boot placed over the wiring end of the switch. 

The control head was a modified Motorola MCR-100 design, however these radios otherwise share nothing with the MCR-100.  It is not known why Motorola chose to build the CHP motorcycle radio out of two Maxar under-dash mobile radios, instead of modifying the MCR-100 equipment, which was already a motorcycle radio.  The Maxar was a cheaper piece of equipment (in terms of price and quality) and possibly being able to be the low bidder was one reason. As in the CHP Micor mobiles of the same era, the motorcycle sets had dual receivers to allow monitoring the car-to-station channel, and separate PL tones for each receiver.  The Maxar radios required a larger than normal weather housing, which was a white version of the MCR-100 fiberglass housing with a spacer between the base and the top cover.  That spacer was lettered "California Highway Patrol" on each side.

The majority of these Maxar radios were taken out of service and scrapped by 1993, and were almost entirely replaced by the GE RANGR model described below.  However, some Kawasaki Police-1000's which left CHP Motor Transport in 1987 were still equipped with these Motorola radios, and continued in service until they were eventually surplused, which in some rural areas occurred many years later.  In fact, it was recently brought to my attention (Oct. 2007) that there is a KZ-1000 in the Santa Cruz area office still in service, with the Maxar radio, with over 200,000 miles on it!  This setup should not have the mobile "extender" repeater in it, since that was not configured by CHP until much later, and only on the RANGR radios.

Note alternate microphone hang-up position in above photo, modifications by CHP  

GE RANGR MOTORCYCLE RADIOS, 1989-PRESENT:

The GE RANGR automobile mobile radios which began to go into service in 1988 were also supplied in a motorcycle version which featured a simplified (S-815) control head without the warning light and siren controls of the mobile S-810 control head. It is believed that the majority of the GE motorcycle radios did not start being installed until 1989, the car changeover being accomplished first.  The Maxar radios began appearing in CHP scrap in early 199, although they were not removed from in-service motorcycles, and apparently, as of 2008, there are still a few Kawasaki KZ-1000 cycles in low-usage divisions which are still fitted with the Maxar equipment.   The RANGR motorcycle radio chassis itself is a 40 Watt version of the mobile as used in the cars. 

Beginning in 1996, a mobile repeater was added to the motorcycle RANGR package. That repeater consisted of a specially modified GE M-PA portable radio, and fit in a specially constructed spacer between the RANGR mobile and the top cover.    CLICK HERE for a pdf copy of the service manual for this repeater (approx. 1.1 Mb pdf file.)

Initially, during the use of the Kawasaki motorcycles, the GE radios were supplied in a white GE fiberglass radio housing, with a flat top.  When the "extenders" were added in 1996, GE supplied a spacer to raise the top of the housing.  Some of these spacers were lettered "California Highway Patrol" while others were not.  At the time that the BMW cycles began to be placed into service, the GE housings were surplused, as the factory BMW streamlined radio box is sufficient to fit all the equipment inside.  The BMW installations continue to use the GE  M-PA modified hand-held radio "extender" although at some point, the "extender" operations are switching to 700 MHz with the transition to the EF Johnson hand-held radio (see my "CHP 2009" radio page) and the GE "extender" units will have to be removed.

There is a pushbutton assembly added to the left lower end of the handlebar area for the radio PTT and PA feature.  This appears to be an optional BMW part available from dealerships.  The current CHP assembly has three pushbuttons.  I don't have a close-up photo of it but there is at least one shown over on the Flickr website should you search using "CHP BMW" as the search term.

The RANGR equipment is now twenty years old yet still in service.  Evaluation orders have been drawn up for a motorcycle version of what was originally called the Visteon Tac-Net multi-function controller, as proposed for cars in 2003.  With with the state of the economy in 2009 it is not known how soon this will occur.  The original Visteon project has become the Rockwell-Collins/Lectronix "CPVE" project in the meantime.  Presumably the next generation of motorcycle radios will be Kenwood units, as they are one of the only manufacturers still producing low band equipment.

CLICK HERE FOR A PDF FILE OF THE CHP MOTORCYCLE SPECIFICATIONS AS OF 2007

The following photos of Redwood City motor units  are courtesy of Tim Tyler

The hand-held radio for motorcycles was the same as used by the patrol car officers, but was not used until the "extenders" began being placed on motorcycles.  Initially, that radio was the GE MPS series hand-held, although those were fairly quickly replaced by the  Motorola HT-1000. See my main "CHP 2001" radio pages for photos and further details of the hand-held radios.

ANTENNAS

The antennas on the current BMW motorcycles are an Antenna Specialists Corp. product  which is made specifically for CHP, and CHP has added a small matching box in-line with the antenna as well. The cylindrical tube is apparently the loading coil housing, which seems slightly longer than the traditional coil assemblies used on 42 MHz shortened antennas.  What would normally be the steel spring between the whip and the loading coil is in this case a molded rubber flex assembly, as shown in the photos, and the radiator is a standard white fiberglass motorcycle whip.   I don't know the reason or function of the antenna matching box at this point.  Antenna Specialists has changed hands at least once in recent years and is currently a division of PCTEL Corporation, which also owns Maxrad Antennas.  The  PCTEL part number for the antenna is the same as the old Antenna Specialists part number:  ASP RD 720 CHP  .  The "CHP" at the end of the part number indicates it is a special item made for them.

The "extender" repeater antenna is as shown in the photos above, a rubber VHF portable style antenna mounted on an angle bracket near the windshield.

Photos and information on the present CHP mobile radios can be found at my CHP 2001 web page:  CLICK HERE

Photos and information on the previous generations of CHP mobile radios can be found at my CHP Radio web page: CLICK HERE

Also, check out my web page of Motorola pre-WWII police radio equipment  CLICK HERE

This page created by Geoff Fors, Monterey California, copyright June 22, 2002, all rights reserved. Not sponsored by or connected with the State of California or the California Highway Patrol. If you have any additional information, historical data or photos, or have any suggestions, please do contact me by e-mail. I hope to find others who are also interested in preserving this history.

E-mail me at geoff @wb6nvh.com. I am always looking for CHP radio equipment, parts, manuals, etc. for this "virtual museum" and my collection, particularly the pre-1960 equipment, as well as almost any ancient land mobile radio equipment and documentation. I am still trying to find the RCA radio drawers for the Super Carfone and Super Fleetfone 1960's radios, motorcycle equipment pre-1978, and control heads for the Philco prewar police receiver and the RCA CMV-3 "Fleetfone." Don't let history wind up at the landfill ! 

 Last updated: 12/21/2009                                                                                       Copyright 2001, All rights reserved

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