CHP 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 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 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 speaker while others had a dark silver-gray speaker. See the 1952 accident scene photo below.
THE MOTOROLA TWIN-V RADIOS, 1956-64:
Beginning in late 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 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."
It is presumed that 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.
THE MOTOROLA INDUSTRIAL DISPATCHER RADIOS, 1958-77:
Some of the" Twin-V" motorcycle radios were experimentally replaced in approximately 1958 by the new Motorola "Industrial Dispatcher" hybrid motorcycle radios, a one-piece set which made extensive use of transistors and which was shock-mounted within a hard fiber 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. 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!
In approximately March 1960, more of the remaining Twin-V motorcycle radios were replaced by the newer Industrial Dispatcher sets, model T31AAT-1114A, but all three types remained in service through at least 1963. The fleet of remaining older equipment was converted to "narrow band" operation (5 KHz FM deviation) in 1962-63 and almost all 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 through 1967 by 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 Industrial Dispatcher models were eventually supplemented by the Z31BAT Industrial Dispatcher, starting in 1967, apparently the last major order for Motorola of this already obsolete equipment, which was promptly discontinued by Motorola immediately afterwards in favor of all-transistor designs. The Z31BAT was a special model made specifically for the CHP. The essential difference of the Z31 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. The 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.
THE MOTOROLA MAXAR RADIOS, 1977- ~1990.
The Industrial Dispatcher radios were so successful that same basic design remained in 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" radios 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 into the early 1980's.
This Maxar 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.
THE GE RANGR MOTORCYCLE RADIOS, 1989-PRESENT:
The GE RANGR mobile radios which began to go into service in late 1987 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 the late 1980's, the car changeover being accomplished first. The Maxar radios began appearing in CHP scrap in early 1992. The 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 consists of a specially modified GE MPA portable radio, and fit in a specially constructed spacer between the RANGR mobile and the top cover. It is believed that the MPA repeaters have since been replaced with a Pyramid SVR-200 series unit.
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, GE supplied the spacer mentioned above 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. It is believed that the BMW installations now use the Pyramid "extender" rather than the first generation GE MPA equipment.
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.
Photos and information on the present CHP mobile radios can be found at my CHP 2001 web page: http://www.mbay.net/~wb6nvh/CHP2001.htm
Photos and information on the previous generations of CHP mobile radios can be found at my CHP Radio web page: http://www.mbay.net/~wb6nvh/chpradio.htm
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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.
Because of SPAM problems relating to an automatic link to my e-mail address, you can no longer directly e-mail me by clicking on a link. Instead, just manually enter my e-mail address which is wb6nvh@ mbay.net . 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 ! .
Also, check out my web page listing Motorola pre-WWII police radio equipment, at http://www.mbay.net/~wb6nvh/Motadata.htm
Last updated: 10/18/2007