Kenwood ts830s no drive on 20 meter band

Discussion in '"Boat Anchor" & Classic Equipment' started by M3UZB, Jul 10, 2018.

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  1. M3UZB

    M3UZB Ham Member QRZ Page

    Hello

    I'm unsure if I have posted this into the right category, but I,m sure I will be corrected.

    I was wondering if anyone had any idea what could cause the inability to peak the drive when tuning up on the 20 meter band?

    All the other bands work fine and full output into a dummy load and able to tune up just fine.
    20m is the only issue.

    Any help with this problem would be very much appreciated.

    Best regards

    Simon.

    M3UZB
     
  2. G3YRO

    G3YRO Ham Member QRZ Page

    Question 1 - is the calibrator signal the same strength on Receive when you peak the Preselector knob on 20m? (what Kenwood have labelled DRIVE)

    Question 2 - do you have no drive at all? (and therefore no output) . . . or is it just rather low?

    Roger G3YRO
     
  3. M3UZB

    M3UZB Ham Member QRZ Page

    Hi roger
    I have not had the callibrator on.just gone through the normal tuning procedure.
    I have no drive at all on 20m and no output registered on the power meter but works fine on all the other bands
     
  4. N8YX

    N8YX Ham Member QRZ Page

    First thing to do is inspect the bandswitch wafers on the RF Unit. I'd give them a proper cleaning. Roger prefers Servisol, I use D5-100 in the dropper bottle (applied sparingly to the ring and to the wiper tab of the ring). YMMV. Let sit for a few minutes then gently wipe the ring contacts of each deck with a Q-tip while rotating the switch knob.

    Check to see that you have a calibrator signal on the band, and that it can be peaked (as stated above). If you have a scope, probe the DRV land on the RF Unit PCB (right side of the board, under VC3 - w/ blue wire connected to it) and see if you have adequate drive power on 20M.

    If you do and the rig still doesn't produce output on 20M, it's time to look at the PA bandswitch and all components connected to the 20M contact.

    Did this issue develop suddenly? Or is the rig new to you with unknown history?
     
  5. G3YRO

    G3YRO Ham Member QRZ Page

    Well before you do anything else, check it on Receive first ! (in a Transceiver, much of the circuitry is common to Transmit and Receive . . . and in my experience, most Tx faults are in the low level circuits, not the PA)

    Let me know what you find . . .

    Roger G3YRO
     
    KE4OH likes this.
  6. M3UZB

    M3UZB Ham Member QRZ Page

    Hi thank you for you're suggestions I will try the cleaning method you described and see if that yeilds any results.

    I don't possess any scopes or anything like that just basic DVM and an old feedback fm610 frequency meter that's about it really.

    The radio was bought by myself From a radio rally. it's has unknown provience.
    The PA sheild is missing and the frequency counter fails to display on the odd occasion I have to rotate the mode selector then it comes to life?as it's the only radio I have at the moment I'm very keen to get it going properly.

    I bought the partial final cage repair kit from America and a brass coupler for the band switch.the 6.8uh RF inductor was burnt when I inspected the radio when I got home from the rally as .i did not want to plug the radio straight in at that time just in case.

    Thank you so much for you're reply.

    Best wishes

    Simon

    M3uzb
     
  7. M3UZB

    M3UZB Ham Member QRZ Page

    Hi Roger

    When you say check it in receive first. do You mean peak the drive for maximum noise?
     
  8. W5INC

    W5INC XML Subscriber QRZ Page

    Possibly?

     
  9. M3UZB

    M3UZB Ham Member QRZ Page

    Peaking the drive for maximum noise on receive with calibrator on works it peaks to 9 s points
     
  10. N8YX

    N8YX Ham Member QRZ Page

    Simon,

    Look at the two rear-most bandswitch wafers on the RF Unit. Those interact with the Driver portion of the assembly.

    I'm betting either a dirty contact or a failed switch, assuming someone didn't apply the Golden Screwdriver to the 20M Drive coil.
     

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