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TS-530s can't peak load control

Discussion in '"Boat Anchor" & Classic Equipment' started by KD5NDQ, Apr 14, 2019.

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  1. W5RKL

    W5RKL Ham Member QRZ Page


    Unless the final tube plate voltage failed in transmit by either an open in the HV lead to the final
    tubes, a failure in the HV supply, or the plate caps on both final tubes were removed, which would result in the final
    tube screens becoming the PLATE, more than likely the final tube 100 ohm screen resistors will be okay.
    Those screen resistors don't normally fail since the current level is low.

    The typical final tube cathode resistance, measured from either final tube pin 1 to ground, will be approximately 5 ohms.
    An increase of 5% is normal and should not be an indicator to replace the cathode resistors.

    With 60ma indicated in CW mode, the final tube cathode voltage will be approximately 300mvdc

    0.060 x 5 = 0.300vdc

    If the PLATE current in CW mode is 90ma then the final tube cathode voltage will be approximately 450mvdc

    0.090 x 5 = 0.450vdc

    You also said

    Yes no dip in plate current, but only roughly 60mA of current in CW mode. In TUNE mode it shows roughly 90mA.

    Without major mods, it's not possible to have an increase in plate current (IP meter indication) in TUNE mode verses CW mode.
    In TUNE mode Rectifier Unit R15 reduces the final tube screen voltage by approximately 50% resulting in a "Decrease" in final tube
    plate current not an "Increase" in final tube plate current. Are you sure you are reading the PLATE current in TUNE and CW mode
    correctly? Is it possible you have them swapped, 90ma in CW and 60ma in TUNE? Also, in TUNE mode the no drive final tube
    idling current will be "less than" 60ma not an increase in plate current of 50% (90ma). In CW mode the normal no drive final amp
    idling current is slightly higher than 60ma.

    Mike W5RKL
  2. KD5NDQ

    KD5NDQ Ham Member QRZ Page

    Checking it just now, in TUNE mode plate current is 90mA and can be dipped to 45mA. In CW mode it stays at 75mA (I think my eyes were tired last night), no matter LOAD or where PLATE setting is.
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Maybe the key jack is open circuited due to oxidation on the internal jack contacts.

    Did you try plugging in a key into the key jack and closing the key contacts on CW?
  4. KD5NDQ

    KD5NDQ Ham Member QRZ Page

    I've actually never used a key on this rig as I am new to CW - I am enrolled in the CWOps class right now! That being said, when I plug a key in and flip the MODE switch to SEND, per the 530 manual, and close the contacts on the keyer, the reading on the meter goes from 75mA in the SEND position to around 100mA with the keyer key closed.

    I didn't realize you have to keep the send switch in SEND mode for CW transmission and then flip it back off??? That would take some getting used to!
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Yes, that's required. You'd normally only do that once per transmission, and when your transmission is finished, flip it back down.*

    That the plate current goes much higher when you close the key (with SEND switch up) indicates the rig is working, the 6146 cathode resistors are intact, etc.

    Now, with the key plugged in and CLOSED, with the SEND switch UP, turn up the CARrier control all the way up and see what the Ip does: peak the DRIVE control for maximum indicated Ip, and see if you can dip the plate current using the PLATE tuning control, and achieve RF output power, which can be maximized by using both PLATE tuning and the LOAD control. If there's sufficient drive and the tubes are good, you should ultimately see >200mA Ip and ~100W RF output power.

    The CARrier control only affects CW, it does nothing on SSB.

    The DRIVE control peaks the drive to the final amplifier and must be adjusted for each band or if you change frequency much within a band.

    *Note: I should mention the 530S also provides semi-break-in CW operation that does not require flipping this switch, if you simply turn VOX on while switched to CW mode. That should make the transmitter operate as soon as you close the key, and go back to receiving when you release the key, with some delay set after release (the delay is adjustable).
    Last edited: Apr 19, 2019
    KA0HCP likes this.
  6. KD5NDQ

    KD5NDQ Ham Member QRZ Page

    Yes in CW mode increasing the CAR control I can increase the IP when the key is down as well to dip the plate and can get >200mA Ip but only when the key is down. I don't have an external wattmeter.

    Cool, thanks
    Last edited: Apr 19, 2019
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Well of course "only when the key is down," it cannot generate any output at all if the key is not down.

    That's the way it's supposed to work.

    Sounds to me like the rig is working 100% normally.
  8. KD5NDQ

    KD5NDQ Ham Member QRZ Page

    Yep, OK got it. Did not know that before.

    Well, yes, except - it isn't. As I follow the tune up procedure from W2AEW as in this video
    at 2:03 in the video "to tune up at power" in CW mode, adjusting the LOAD control does not move the meter needle at all when the meter is in the RF mode, as I mentioned in Post #1 of this thread.
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    You really need a wattmeter to see what's going on.

    The RF "output" meter in the Kenwood is a relative indication and you can make it read anything by turning its sensitivity control up and down. So any particular meter indication is meaningless.

    However, the load control should have some effect. If it doesn't, maybe a coupler is loose or disconnected and the load capacitor isn't really rotating. You can check that visually.
  10. KD5NDQ

    KD5NDQ Ham Member QRZ Page

    OK I am going to order a wattmeter now, any recommendations used or new?
    There is no change in the meter when adjusting the RF sensitivity from full CCW to full CW.
    The coupler is not loose and the load capacitor is turning.

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