Kenwood tkm-707 cw transmitter question

Discussion in 'Radio Circuits, Repair & Performance' started by W4CBJ, Oct 18, 2013.

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  1. W4CBJ

    W4CBJ Ham Member QRZ Page

    I have a mint Kenwood TKM-707 radiotelephone that I recently acquired. The operating manual (page 9 ... item 6) ... mentions a CW jack that accepts a 1/4 " phone plug for the key or keyer ... on the rear of the set ... but there is no jack there. The set has been modified for Amateur Band use (D111-D114) and want to key the output for CW (on the ham band.)
    Does anyone have info on this subject?
    Joe W4CBJ St. Petersburg, FL <>
  2. W9GB

    W9GB Ham Member QRZ Page

    Last edited: Oct 19, 2013
  3. W4CBJ

    W4CBJ Ham Member QRZ Page

    Thank you for your reply. I am familiar with the cross out. I wonder if the earlier production models had the key jack and the circuitry. They are shown on the illustrations. I imaging that maybe they were deleted because CW is not permitted on the marine channels (OK in an emergency but who might be on the air capable of reading the code?) The service manual shows how to modify the set for the Amateur Bands (lifting D111-D114) so it would be peachy to use this rig
    on the CW portions of the ham bands.
    The mode switch works OK on the receiver side.
    I wonder if it is possible to contact Kenwood engineering and if they would tell you the story ?
    Please advise any further thoughts you may have on this subject.
    Joe W4CBJ
  4. W9GB

    W9GB Ham Member QRZ Page

    Joe -

    That radio case was used for ANOTHER radio -- BUT I can not remember the model (marine, commercial, etc.). It may have been a special order Kenwood model (commercial marine/coast guards, government, military, embassy).

    American mfg. produced a number of Special orders for that radio user segment until 1980s --
    when Eastern Asia assumed that mfg. role from USA.
    If it was my project -- I would pull up Service Manual, place on Electronics bench, and look at PC Board directly (etched patterns for parts -- not installed).
  5. W4CBJ

    W4CBJ Ham Member QRZ Page

    Kenwood tkm-707 ce transmitter question

    Damn good idea ! It was so simple ... I didn't even think of it. I will look and keep you informed.
    Thank you again for your help.

    Joe W4CBJ
  6. IZ3NYT

    IZ3NYT Ham Member QRZ Page

    you have to use the microphone jack, modify it and connect it to the PC, there are programs that decode and transmit CW, when transmitting the radio goes into conduction, and the note sound that comes from the sound card acts as a keyer.
  7. W9GB

    W9GB Ham Member QRZ Page

    That method is referred to as Modulated Continuous Wave (A2A).
    A2A MCW morse can clearly be heard on a normal AM radio receiver.
    It was commonly used by many RDF beacons to send a morse station identifier on a regular basis.

    I think Joe, W4CBJ, desired A1A.
    A1A is signalling by keying the carrier directly (aka CW, OOK).

    On-off keying (OOK) the simplest form of amplitude-shift keying (ASK) modulation
    that represents digital data as the presence or absence of a carrier wave.
    Last edited: Oct 27, 2013
  8. W4CBJ

    W4CBJ Ham Member QRZ Page

    Kenwod tkm-707 CW transmitter question

    W9GB is exactly correct. 73 Joe W4CBJ
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