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Heathkit HW-101 Pilot lamps brown wire shorted to ground

Discussion in '"Boat Anchor" & Classic Equipment' started by KE8NAI, Jun 7, 2021.

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  1. KE8NAI

    KE8NAI Ham Member QRZ Page

    I recently purchased a heathkit hw-101 from an estate sale, with the previous owners callsign WD8BAZ still intact. I sat down today and went through the entire unit and only saw one capacitor that appeared to present an issue. The unit is being powered with and hp-23b power supply and is connected to an sb-600 speaker. Upon first powering the unit on the pilot lamps begin to glow and the tubes begin to glow as they are warming up. However none of the tubes get very bright and except for the voltage regulator tube that glows purple. There is no noise coming from the speaker and the s meter does not move. Going through the trouble shooting guide we have found that there is a dead short from the brown pilot lamp wire to chassis ground which it says is incorrect however tracing this wire we cannot seem to find where the short is. Does anyone have any ideas or have had a similar problem? Any help is much appreciated. I purchased this as my first station, knowing it would take some work to getting it running, but there is just something that draws me to tube radios and especially the heathkit transceivers.
    Thanks for any help and 73!
    KE8NAI
     
  2. VE3EKJ

    VE3EKJ Ham Member QRZ Page

    Incandescent lights like pilot lamps have very low resistance when cold. When power is applied and they heat up the resistance of the filament rises. Try removing the pilot lamp from its socket and then measure again.

    Bill VE3EKJ
     
  3. W9WQA

    W9WQA Ham Member QRZ Page

    pull tubes. measure fil volts. could be transformer short.
    volts will tell.
     
  4. SM0AOM

    SM0AOM Ham Member QRZ Page

    Since all tube filaments and pilot lamps are in series-parallel over a 12.6 V filament winding drawing about 5 A in warm conditions, they represent a load resistance of around 2 ohms to the transformer.

    About half this resistance can be measured from each branch to ground if a good way of measuring them separately while still hot could be envisioned.

    As you obviously have +300 V as the 0A2 lights up, the causes for your problems are most probably found elsewhere.

    Oxidised tube socket or switch contacts are "prime suspects".

    A short over a transformer winding would most probably "trip" the circuit breaker.

    73/
    Karl-Arne
    SM0AOM
     
  5. KE8NAI

    KE8NAI Ham Member QRZ Page

    Thanks everyone for the help so far, upon further inspection today (pulling every tube and checking to see if they were the cause of the issues) I found that one of the final tubes has a physical rattle when moved and has most likely gone bad, there was also a smaller 6ua6 tube that needed to be replaced. With the help of some spare club parts the radio was once again powered on, this time tings began to behave as expected, except there is no sound out through the speaker. I suspect that this is due to a shorted transformer winding or improper transformer connection. I will be checking tomorrow to see if this is the issue as well as if the unit operates properly with headphones. If that is the case i will finally test the transmit function tomorrow as well. Hopefully we will soon be on the air with my first personal HF station.

    73 de KE8NAI
     
  6. W9GB

    W9GB Ham Member QRZ Page

    Mike, W5RKL has a good web site for HW-101
    https://w5rkl.com/manuals/
    HW-101 Restoration #1 (Complete Tear-Down Restoration)
    https://w5rkl.com/heathkit-hw-101-complete-rebuild/
    HW-101 Restoration #2
    https://w5rkl.com/restored-heathkit-hw-101-2/

    Optimizing the Heathkit HW-101, SB100-102 Transceivers
    by Mark, WB8JKR (sk)
    http://www.w7ekb.com/glowbugs/ModsEtc/Optimizing the HW101.pdf

    Heathkit HW-101 HF Transceiver
    Assembly and Operation Manual (245 pages)
    http://www.wmsinc.org/N7EBG/heathkitpdf/HW-101 Manual KB2LJL.pdf

    Heathkit HW-101 tips and modifications from Bench Techs
    http://www.w7ekb.com/glowbugs/ModsEtc/HW-101tips.pdf

    Glowbugs notes on HE-101 and SB-series
    http://www.w7ekb.com/glowbugs/ModsEtc/modifications.htm

    Kees, K5BCQ : Notes
    https://www.qsl.net/k5bcq/102/102.html
     
    Last edited: Jun 8, 2021
    PY2RAF and N2EY like this.
  7. KE8NAI

    KE8NAI Ham Member QRZ Page

    Todays Update so far: The radio is confirmed to receive on the 20 am 40m bands using a pair of high impeadence headphones! This is great news! Trying to troubleshoot the speaker issue now. I have it narrowed to three areas, the transformer, the relay, or the headphone/speaker jack.
    73
    KE8NAI
     
    KA0HCP likes this.
  8. SM0AOM

    SM0AOM Ham Member QRZ Page

    As you have sound when plugging a pair of 'phones in the headphone jack, this rules out the transformer and the relay.

    Left are the switch contact in the headphone jack or the speaker jack itself.

    Never underestimate the amount of oxidised contacts around in a 50 year old radio...

    73/
    Karl-Arne
    SM0AOM
     
    N2EY likes this.
  9. KE8NAI

    KE8NAI Ham Member QRZ Page

    Karl,
    It looks like its a faulty phones jack, any suggestions on how to fix it? The contacts that should be normally closed are no loner normally closed.
    73
     
  10. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Repair or replace. A readily available, low cost item, that can also be salvaged or scrounged from a myriad of other devices.

    p.s.
    Tips:
    1. Common problems with Heath radios in order of occurrence:
    -Bad solder joints.
    -Bad ground points (be sure to re-install those lost star-washers correctly).
    -Dirty wafer switches
    -Dirty contacts
    -Resistors out of tolerance
    -Assembly errors

    2. Check EVERY single component for tolerances, Retouch EVERY solder joint (liquid solder flux is your friend); Trace EVERY wire for correct placement.
     
    Last edited: Jun 8, 2021
    WA1GXC likes this.

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