I posted this question a scanner listserver and got this answer back from a former LAPD Dispatcher.

-----Original Message-----

From: mws72@----

To: SCAN-L@U...

Date: Monday, June 07, 1999 13:02

Subject: ADAM-12's control head

I have been watching Adam-12 on tvland since january. I noticed the control head (a motrac mounted with a Federal Signal siren control) never changed during the seven season run. The markings on it as F1, simu, F2, F3, F4. I suppose Simu is for repeating the cars for crime broadcasts. Did LAPD keep the same control heads in the squads during the 1968-75 period?

On a related note. It looks like the AMC Matador that was used on the show became a LASO squad on Emergency.

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These were the so-called "DFE" (dual front-end) radios, used from about 1967 until at least 1973, probably much later. They may still be in use for the MDT's, which use those old frequencies. The radios back then had very narrow bandwidth [bandspread] (like <2 Mhz), and LAPD's dispatch output channels were in the 158.865 - 159.18 range. Mobiles and Tac frequencies were in the 154.65 - 155.79 range; so they essentially had two "front ends," one for each band segment, in the radio.

The frequency layout in most radios was as follows: (all dispatch freqs were semi-duplex, no repeaters).

F1 - Frequency assigned to the Division the radio belonged to. Received the Dispatch output (Freq A, B, D or E, depending on the part of the city), and transmitted on the division's INPUT freq (Freq 1,2, 3...).

Note that one output freq was shared by several divisions and their dispatchers (actually "RTO's" - Radiotelephone Operators); with some exceptions each division had its own talk-in freq and RTO.

Simul - I'll get to that in a minute

F2 - This was a so-called "Citywide" dispatch frequency, Freq C/8, which was also used by Harbor Division for dispatch. During the 1965 Watts riots, cars coming in from distant divisions couldn't reach Communications Division due to the limited number of receiver sites for each frequency. So they added receivers and transmitters all around the city for this frequency pair. It was hardly ever used, though.

F3 - Tac 1 (F9) Simplex 154.83 - Used mainly by Detectives, except during unusual occurances. Car-to-car.

F4 - Tac 2 (F6) Simplex 154.77 - Used by patrol units for car-to-car.

"Simul" No, not a repeater. We never had ANY repeaters until the T-band "R.O.V.E.R" radios showed up about 1980. The closest thing to "repeating" was during pursuits, when the "link' would crank up his speaker, aim his boom mic at it, and essentially let the unit broadcast his own pursuit.

The "Simul" selection wasn't even really installed in most radios. All the metropolitan area divisions used either Frequency A or Frequency B. "A" in the north end -- Central, Rampart, Hollenbeck, Hollywood, Wilshire and Northeast (was "Highland Park" until about 1969). "B" in the south end -- Southwest (was "University Div" until about 1969), Newton Street, 77th Street, plus all Accident Investigation Div ("T" cars), and Traffic Enforcement Div (Motors...they had two freqs).

Since north end Traffic and Motor units worked in Freq A (159.15 out) areas but used Freq B (158.91), hot-shot calls and crime broadcasts were always "simulcast' on both "A" and "B" so everyone would hear them.

With me so far?

The idea for "simul" in the radios was for specialized units, like citywide detectives & Metro, or others not subject to getting radio calls: they could have reasonably quiet radios, not listening to five or six RTOs continuously babbling all the routine calls and chatter; but any hot stuff Communications would "simulcast" would be received on radios tuned to "simul." I don't think 1% of the officers knew about it or ever used it.

Clear as mud for you?

Oh, the cars. Patrol cars were Plymouth Belvederes from at least 1966 to 1969. In 1970 they got a bunch of sporty-looking Mercury Montegos...with whitewall tires no less. They really looked cool, but mechanically they were real dogs, lasted about a year. Then they went to the Matadors for a year or two, then back to Plymouths - Fury's this time. After Chrysler got out of the "police package" business, they've mostly been using Chevy Caprice's and Ford Crown Vics.

More if you need...better save a few electrons here.

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