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tm-731a pilot lamps

Discussion in 'Radio Circuits, Repair & Performance' started by KC7CNC, Apr 8, 2012.

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  1. KC7CNC

    KC7CNC Ham Member

    I would like to either replace the pilot lamps in my Kenwood Tm-731a with new lamps or LEDs. I cannot find much information on the voltage or mA rating or LED conversion. I have a schematic that shows the incoming voltage as 10.5v (or when dimmer is on 7.8v) feeding two parallel circuits, each containing two lamps in series, each series preceded by a resistor of unknown value. Can anyone help me figure this out?
     
  2. W9GB

    W9GB Ham Member

    Kent -

    Kenwood TM-731a
    http://www.universal-radio.com/catalog/fm_txvrs/tm731a.html

    No big secrets. A quick search at Kenwood Parts East
    http://www.kenwoodparts.com/parts/search.php
    provided part number, and current price (it is in stock). Part (bulb) is used in several radios.

    B30-0865-25 LAMP TM-721A TM-731A TM-741A TM-641A $3.58

    Kenwood Parts West
    http://www.partstore.com/Part/Kenwood/Kenwood/TM731/Kenwood/Kenwood/B30086525/New.aspx

    Service manual will have disassembly pictorials and parts list with Kenwood part number and specs.

    K4EAA sells bulbs used in Kenwood hybrids.
    Rated 12V, 50 ma, 4mm dia., 6" wire leads.#
    Long life, and brightness & color matches originals perfectly.
    http://www.k4eaa.com/parts.htm

    W5CIA also sells bulb on eBay.
    ====
    As far as the dimmer mode --- that can be problematic with LEDs
     
    Last edited: Apr 8, 2012
  3. KA5IPF

    KA5IPF Subscriber

    6.3v 75ma T1
     
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