Gates of Hell - Posting for K3FEF.

Discussion in 'Amplitude Modulation' started by KA4KOE, Jun 7, 2017.

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  1. KA4KOE

    KA4KOE Ham Member QRZ Page

    OK what's left to check?
     
  2. K4KYV

    K4KYV Premium Subscriber Volunteer Moderator QRZ Page

    That should explain the high grid current meter reading. You can adjust the sensitivity of the O/L relay. With full 1 kw (broadcast) out, the normal plate current is about 600 mA. The tripping threshold would be higher than that. Whatever you normally run in amateur service, the tripping threshold should be set to 25% or so higher. Since there is no protective bias in the stock Gates circuit, it depends entirely on the O/L relay for protection of the final tubes.

    I added protective bias to mine so I could use it on CW, but that's a whole other story.

    Maybe the finals are pulling 600+ mA (PA plate out of tune) but the meter reading way off.
     
  3. K4KYV

    K4KYV Premium Subscriber Volunteer Moderator QRZ Page

    Grille.JPG
     
    K3FEF likes this.
  4. K3FEF

    K3FEF Premium Subscriber QRZ Page

    A series of wondrous blunders have all been resolved. The grid current meter had me on a wild goose chase. Once I had that fixed, the balance of the troubleshooting all made more sense. She's tuning up nicely and now I'm doing some more testing. But high voltage is holding nicely!
    THANK YOU EVEYBODY! :)
    (You guys don't want to know what was wrong, do you?? LOL)
     
  5. KA4KOE

    KA4KOE Ham Member QRZ Page

    Why was the HV tripping out? Explain please becuz darn tootin' we wanna know.
     
  6. K3FEF

    K3FEF Premium Subscriber QRZ Page

    2 primary causes:
    #1: 240V was on the wrong terminals on the HV transformer giving me 3100V instead of 2300. That threw EVERYTHING off!
    #2: The tank circuit had one capacitor incorrectly wired.
    I knew it was going to end up being something goofy. On the bright side, it revealed a lot of the other issues that are now fixed. AND I got the fans going, pilot lights, and the roller inductors up top are nice and smooth now.
    She's running like a champ now (the transmitter - not the XYL, W3TKP). I'm about to give it audio. Nice and quiet on 1450AM - no hum - just a strong quiet carrier.

    [​IMG]
     
    AA6LK likes this.
  7. K4KYV

    K4KYV Premium Subscriber Volunteer Moderator QRZ Page

    That transmitter must have been originally designed for 1000w/500w operation, or at least that's where the plate transformer came from. The 1000w-only and the 1000w/250w versions' stock plate transformer is 3100v only, with 250w achieved by switching the transformer primary voltage source to 120 volts instead of 240.

    Glad to hear Phase I of the mission is accomplished.
     
  8. KA4KOE

    KA4KOE Ham Member QRZ Page

    Did you pull one of the terminals off the HV rectumfryers to get it at low power per the manual?
     
  9. KA4KOE

    KA4KOE Ham Member QRZ Page

    19025043_10212177740457317_277311674755252167_o.jpg
     
    KE4OH and KD2ACO like this.
  10. KA4KOE

    KA4KOE Ham Member QRZ Page

    It was wired for those two power levels.
     

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