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  Breaking Down the 3-letter, 4-digit Motorola Product Assembly Numbers
By Mike Morris WA6ILQ
with contributions and editing
by Robert W. Meister WA1MIK
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This information was compiled from a reference page in four different vintages of Motorola Buyer's Guides dating from the mid 1960s to the late 70s.
If anyone has newer information please let us know.

Overall Format
Prefix Suffix Version Special Products (rarely found)
Letter Letter Letter Number Number Number Number Letter Zero, one or two letters or numbers -SPnn

Obviously, the -SPnn (where nn is a sequential design number) is only found on special purpose / special product units.
To understand any SP unit you need the base manual, and preferrably the documentation that was written for the modified unit.

Examples that follow this scheme:

  • DPL (Digital Private Line) test set, model number SLN6415A
  • MSF5000 digital metering panel, model number TLN2419A
  • MSF5000 UHF power amplifier, model number TTE1450A

    Other letters have been added or assigned to the first and second letter tables since this list was formulated in the 1960s. Some of the meanings have been ignored, redefined or modified as well. For example, the desk charger for a Genesis portable radio (HT600 / MT1000) has a model number of NTN4633A; this is clearly not a transmitter. A MaxTrac UHF RF board is model number HLE9310A, clearly not a housing or cabinet. A MaxTrac 900 MHz conventional firmware EPROM is model number FVN4019A; I won't even try to explain that one. If I had to form an opinion, I'd say that the people that assigned the part numbers seem to have lost the "formula".

    1st Letter - Major Category
    N Portable product (i.e. Florida manufacturing plants)
    S Test Equipment, CCTV, traffic light equipment and other special products
    T Two-way radio product (i.e. Illinois manufacturing plants)

    2nd Letter - Product Type
    A Antenna related but not duplexers, filters or feed line
    B Boxes or packaging kits (mostly used internally by Motorola)
    C Control equipment (control heads, control panels, etc)
    D Drop-ship items (i.e. product manufactured outside Motorola, and shipped directly from the original equipment manufacturing plant to the end customer). This category included antenna system parts like duplexers, Heliax™ feedline, etc.
    EService kits and conversion kits
    F Filters and duplexers, can be Motorola sourced or drop shipped.
    GPanels (mostly metering panels)
    HHousings and cabinets
    JCoil kits
    KCable kits
    LMiscellaneous non-categorized items
    MMicrophones
    PPower supplies and power supply related equipment
    RReceivers and receiver related
    SSpeakers, earphones, and related
    TTransmitters and transmitter related
    UUnified chassis

    3rd Letter - Frequency Range
    AUnder 25 MHz
    B 25-54 MHz (yes, the table in the buyer's guide included 10 meters and 6 meters)
    C72-76 MHz   (see note 1)
    D144-174 MHz   (see note 2)
    E406-470 MHz   (see note 3)
    F890-960 MHz
    N Not frequency dependent (like an audio-squelch board, or a power supply)   (see note 4)

    NOTES:
    [1]: C was limited to the 72-76 MHz USA assignment (one split) until Motorola started making land mobile equipment for the European 66-88 MHz band (which usually required two splits). Some books say that the so-called "mid band" is 60-99 MHz. There is no 30-50 MHz low band in Europe; when they refer to low band they are referring to 66-88 MHz.

    In the USA, 60-66 MHz is television channel 3, 66-72 MHz is TV channel 4, the 72-76 MHz frequencies are used as "Operational Fixed / Repeater" frequencies (essentially commercial point-to-point links), 76-82 MHz is TV channel 5, 82-88 MHz is TV channel 6, and 88-108 MHz is commercial FM broadcast. One rumor is that as part of the HDTV conversion in the USA the FCC and the military want to eliminate TV channels 4, 5 and 6 then reassign the 66-88 MHz range as a military band that aligns with the rest of the world (i.e. for joint operations and exercises).

    [2]: D was redefined downwards to 136 MHz at some point.   There are high band equipment models specified as 136-150 MHz, and others that are 150-170 MHz.

    [3]: E was redefined downwards to 390 MHz in the early 70s and then to 360 MHz in the early 80s for certain military, government and spook equipment. It was expanded upwards to 490 MHz and later to 512 MHz as the 470-494 MHz then 494-512 MHz frequencies were allocated. A 1990s salesmans order book has the UHF band listed as going from 400 MHz to 520 MHz. There has also been some "interesting" equipment found on frequencies as high as 550 MHz.

    [4]: N is still used as a "Not frequency dependent" identifier even when there is some difference between wideband and narrowband equipment (like in the audio recovery circuitry in an IF / discriminator board). Most of the time a variation like that is handled in the final letter suffix (i.e. a TLN9999A1 might be wideband and a TLN9999A2 might be narrowband), but there are exceptions.

    The four numbers after the three letters are simply a design sequence number. One or two letters after the numbers are a version, variation or revision identifier (the term used depends on which book you read). Almost all assemblies have one letter after the sequence number (i.e. the first shippable design is dubbed version A), some have two characters, a few have three (i.e. TLN9999A1A).

    Acknowledgements and Credits:

    As said above, this information came from four different 1960s and early 1970s vintage Motorola Buyer's Guides. I'd like to thank Neil McKie WA6KLA and Don Root WB6UCK (now K6CDO) and as they gave me my first two, and I found the third and fourth at a local ham radio swap meets.

    Contact Information:

    The author can be contacted at: his-callsign // at // repeater-builder // dot // com.



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    This page originally posted on Wednesday 29-Aug-2007


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