TS 830S Driver Tube

Discussion in '"Boat Anchor" & Classic Equipment' started by SA4MDN, May 15, 2018 at 1:54 PM.

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  1. SA4MDN

    SA4MDN Ham Member QRZ Page

    Just a curiosity question really, I had the driver tube fail yesterday during tune up, tuned up the driver stage first alc meter readings were fine no slow dropping of the meter worked as it always has, carrier control in its normal place for the band I was on, couple of seconds into the final stage tune up meter dropped to zero, went back and started all over again but had no drive no matter where the carrier or drive knob was, so question is do driver tubes fail just like a light bulb popping without signs of going soft beforehand, or is this out the norm for the tube, popped a new tube in and all working ok now, tested it on all bands except 160 works a treat.


    Michael SA4MDN
     
  2. G3YRO

    G3YRO Ham Member QRZ Page

    No . . practically never !

    Unlike Transitors, Valves normally just gradually loose emission.

    So that is very unusual in my experience.

    Perhaps the filament went open circuit - was it still glowing? (although I've never had that happen either)

    Roger G3YRO
     
  3. KA9JLM

    KA9JLM Ham Member QRZ Page

    I agree, normally no.

    But the tube socket can have bad connections and cause problems.

    The band switch being dirty can too.
     
  4. SA4MDN

    SA4MDN Ham Member QRZ Page

    the heater element was still glowing
     
  5. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Have you verified the failure mode by re-inserting the 'bad' tube? What you describe sounds like an intermittent connection, perhaps at the band switch as others have noted or perhaps somewhere around the tube itself or maybe at interconnections to the RF driver board. It's very easy in those situations to incidentally bump the loose connection while replacing a part, if that happens then things start working again and it's easy to conclude that the suspect part was indeed bad but the part is actually fine.

    Maybe your tube really did fail in some unusual way but when troubleshooting with socketed parts that can't be easily tested out of circuit it's good practice to validate the root cause by temporarily re-inserting the part to see if the failure mode returns. Of course that only applies to things like you've seen like low gain and not to dramatic short circuit or other conditions that might lead to additional damage. When I worked as a technician and later as an engineer that oversaw groups of technicians we worked hard to validate root cause and avoid 'shotgun troubleshooting' as simple part swaps that appeared to fix a problem often led to multiple returns from the customer.

    If re-inserting the driver tube re-creates the drive level problem or if you can validate that the tube has lost gain via other methods like a tube tester or another test rig then it's likely you've found the root cause and your tube experienced some atypical failure mode. But when in doubt and when re-inserting the tube is low risk to other circuitry it can be a good practice to validate failure modes and root cause and only takes a few seconds to do once the rig is opened up.
     
  6. SA4MDN

    SA4MDN Ham Member QRZ Page

    update, after reading your reply's got me thinking, so I ran the band switch through a few cycles and popped the tube in and out of its socket a few times put the old tube back in and low and behold it works, so dirty socket and or band switch,
    thanks guys,
     
  7. SA4MDN

    SA4MDN Ham Member QRZ Page

    K7TRF, our posts crossed yours popped up just at the moment I sent my update
     
  8. N8YX

    N8YX Ham Member QRZ Page

    Kenwood x20 and x30 series band switches need a bit of TLC from time to time. A modest application of DeOxIt D5 100% (applied to the wiper contact and the ring, followed by a brief set-up time and gentle wiping with a Q-tip) usually keeps them humming right along.

    I do this to my hybrids every time they're on the bench for servicing.
     
  9. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Yeah, I saw them come in at almost the same time. Glad you didn't just throw out your driver tube.
     
  10. SA4MDN

    SA4MDN Ham Member QRZ Page

    Thanks for all the advise and reply's, no kept the tube just in case and it worked out well, will set about cleaning things up in the near future.

    thanks again
     

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