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TS 440 with no RF output

Discussion in 'Radio Circuits, Repair & Performance' started by N9CQB, Jun 29, 2021.

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  1. N9CQB

    N9CQB Ham Member QRZ Page

    Someone gave me a TS 440S that does not have any RF output
    It receives just fine
    When connected to an external wattmeter and dummy load, both the radio output meter and wattmeter show zero.
    the transmit light comes on when keyed, however.
    I’ve taken the radio apart and don’t see any obvious damage.
    There is white sticky stuff on one of the final transistors that holds down what looks like a thermal device.
    I’m not very adept to troubleshooting circuits, so I was hoping someone could tell me what to look for
    Tnx for any advice
    73 de N9CQB
     
  2. G3YRO

    G3YRO Ham Member QRZ Page

    So is there any output on FM, AM or CW?

    Roger G3YRO
     
    KK9W likes this.
  3. N9CQB

    N9CQB Ham Member QRZ Page

    Roger,
    No output on any mode including AM, FM, SSB and CW
    The radio’s meter does deflect when ALC and SWR is selected, but no deflection when in PWR setting. Likewise, no RF output shown on external wattmeter
    Any ideas on where to start?
    I’ve looked at the service manual tx tests. It says to connect the signal from the RF board to an oscilloscope, but I’m not sure how to do that
    My Kenwood station monitor SM220 has a scope but not sure if I connect to the vertical or horizontal input on the scope to test whether the RF board is even producing a signal to the final board
     
  4. G3YRO

    G3YRO Ham Member QRZ Page

    What do you mean by that?

    When you drive the rig (like speaking into the Mic on SSB) does the ALC read as you modulate, as it would normally?

    And what does the SWR Meter read?

    Roger G3YRO
     
  5. N9CQB

    N9CQB Ham Member QRZ Page

    When speaking into mic on SSB or key down on CW, the ALC and SWR meter on the rig deflect fully
    The automatic tuner doesn’t seem to work. You can hear it try to tune, but it just spins and spins
    I have another rig with a built in tuner, so I know my antenna is resonant on 20, 15 and 10 meters
     
  6. G3YRO

    G3YRO Ham Member QRZ Page

    Then it sounds like you have no connection between the output of the internal Tuner and the Antenna socket.

    That could just be a dirty connector . . . faulty cable . . . or faulty/dirty Antenna Relay.

    I think that rig uses tiny coax plugs internally - try unplugging and cleaning.

    Roger G3YRO
     
  7. N9CQB

    N9CQB Ham Member QRZ Page

    Tnx Roger for replying
    I found the service manual online.
    I connected an oscilloscope to the drive output on the RF board and get a normal looking envelope on CW/SSB
    I get the same envelope after the finals
    So, I assume one or more final transistors, the IF amplifier or transformer on the final board is bad
    I checked all the mini coax cables and verified a good connection.
    I’m going to send it to an OM in Texas who will figure out the problem as I don’t have the right equipment to perform the tx chain level tests the service manual requires
    Tnx and 73 from across the pond
     
  8. W9GB

    W9GB Ham Member QRZ Page

    Did you Contact your LOCAL Area Resource? You could Drive it there (and Drop Off).
    Matt Adrian, KD8ZB is the Owner of SAR Technical Services
    in St. Joseph, Michigan.


    SAR Technical Services (St. Joseph) is an Icom service center,
    BUT have repaired other radio brands — before they became an Icom Center.

    SAR Technical Services
    1792 Nash Dr.
    St. Joseph, MI 49085
    http://www.sarts1.com/
    Telephone: 269-429-2334 (8:00 AM – 5:30 PM EST)
    Email: sarts@qtm.net

    ==
    Jahnke Electronics is closer to you than Texas, based in Green Bay, Wisconsin.
    They specialize in Kenwood Radio Repairs, like your TS-440S HF transceiver.
    https://jahnkeelectronics.com/repairs/
    Telephone: 920-819-6756
    Email: info@jahnkeelectronics.com
    ==
    eHam.net Reviews
    Amateur Radio Equipment Repairs

    Jahnke Electronics, Green Bay, WI
    https://www.eham.net/reviews/view-product?id=11837

    SAR Technical Services, St. Joseph. MI
    https://www.eham.net/reviews/view-product?id=5629
     
    Last edited: Jul 4, 2021
    K7SWT likes this.
  9. N9CQB

    N9CQB Ham Member QRZ Page

    Excellent!!
    Thanks I’ll give them a ring
     
  10. G3YRO

    G3YRO Ham Member QRZ Page

    Then there's nothing wrong with any part of the PA ! Just the connection through to the Antenna socket.

    As I suggested it to you, it's probably just a bad cable connection (which may be due to a dry joint on the board) . . . or a bad Antenna Relay.

    All of this can be simply tested by measuring Resistance with a Multimeter . . . you don't need any special test gear.

    Roger G3YRO
     

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