Bauer Power On

Discussion in 'Amplitude Modulation' started by KA4KOE, Apr 21, 2017.

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  1. KA4KOE

    KA4KOE Ham Member QRZ Page

    Making Bauer power: Hit plate HV ON in low position after doing some prep recommended by W7TFO. I just noticed that there are 3 Amperex tubes and some other type that is a bit shorter than the others (in the final). Putting out 120W on low power setting. Meters need zeroing up. The adjusters do not work (jarred during moving?) so I am guessing a little low. Plate current in the neighborhood of 80 mA. HV around 1500 per spec. The mod tubes are showing a ring of blue (not too much) around the glass near the bottom of the grey cathode (with current). Ran a little mod current (that's when the blue shows up) and one tube started getting red and the other did not. Was really careful. Meter readings not meaning a whole lot but at least things are looking up. Thinking I will need to get a new set of tubes regardless.
     
    AF6LJ likes this.
  2. KL7AJ

    KL7AJ XML Subscriber QRZ Page

    Verry cool....or very hot. :) You might want to just run the filaments for half a day, just in case there are some gas issues.....if you can afford the electricity. :)

    Meters are easy to check, but you need to have everything shut down. (and I hope you have a chicken stick and know how to use it). A battery and a variable high value resistor can be used to check each ammeter.

    Be sure the faces of the meters just don't have some static on them.....a little spit does a good job of discharging meter faces. :)

    Slow and deliberate wins the race on these puppies.
    Eric
     
    WZ5Q and AF6LJ like this.
  3. KA4KOE

    KA4KOE Ham Member QRZ Page

    Meters work, it's just the needles are on the left of zero and cant be adjusted with the screwdriver. Yes, I have a chicken stick.
     
    AF6LJ likes this.
  4. KA4KOE

    KA4KOE Ham Member QRZ Page

    Meters removed, carefully cleaned up, and needles zeroed. These are Hoyt 2450 panel meters. The cross bar and adjusters are aluminum and have that "furry" look when they've been sitting in high humidity for a couple of decades. Meters centered up with small precision screwdriver. The adjusters are very stiff and for the life of me couldn't get the little adjusters centered up with the pins. Hoyt is still making these meters today. hoyt.JPG

    Lesson: Remove the 6AC7 RF driver tube when working on the meters. If you are not careful during the meter removal, your elbow can strike this tube and break it loose from the bakelite base. Ask me how I know this.
     
    AF6LJ and KI6IPO like this.
  5. K4KYV

    K4KYV Subscriber QRZ Page

    So the problem was, the adjuster was corroded enough that it was frozen in position, and you managed to break them loose without having to take the meter apart?
     
    AF6LJ likes this.
  6. KA4KOE

    KA4KOE Ham Member QRZ Page

    They were not frozen in place, but almost. I priced new meters: they are 100 apiece. But they are now zeroed and they work. All I removed were the front bezels.
     
    AF6LJ likes this.
  7. KA4KOE

    KA4KOE Ham Member QRZ Page

    New 4-400s and a 6CA7 RF driver on the way (reference my next to last post preceding this one) as well as a new main power on contactor.
     
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  8. K4KYV

    K4KYV Subscriber QRZ Page

    It wouldn't hurt to wiggle the zero-adjust screw back and forth a couple of times every 6 months or so to keep them from seizing up again.
     
    AF6LJ likes this.
  9. KA4KOE

    KA4KOE Ham Member QRZ Page

    Bauer 707 update: New 4-400s due in tomorrow....no RF out, however, until a new 6AC7 driver arrives as well. The driver died in an unfortunate accident while the top row of meters were under repair/cleaning.
     
    AF6LJ likes this.
  10. KA4KOE

    KA4KOE Ham Member QRZ Page

    All new tubes light up. Waiting on new driver....then we apply the HV.

     
    AC9QC and AF6LJ like this.

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