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HA-10 Warrior Panel Meter

Discussion in '"Boat Anchor" & Classic Equipment' started by N2TC, May 11, 2021.

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  1. AF7XT

    AF7XT Ham Member QRZ Page

    Hey @N2EY :)
    now on to irregular content ...
    This is for the Sb-220 but the principal is the same
    All this was derived from

    https://www.w8ji.com/metering_amplifier.htm

    Now of course the part numbers don't match and the metering circuit is a bit different but sometimes the analogy holds.

    YMMV
     
    N2EY likes this.
  2. KI4ZNV

    KI4ZNV Ham Member QRZ Page

    Don't forget to clean the contacts on that rotary switch! A little cramolin may do wonders!
    --scott
     
  3. N2TC

    N2TC Ham Member QRZ Page

    Had done that. Resistance across those 3 parallel 4.7 ohm is 2.4 - a bit high (should be 1.57). Color me stupid: completely forgot about checking the bias jumper. Not home now but will check later.
     
    N2EY likes this.
  4. N2EY

    N2EY Ham Member QRZ Page

    If the three parallel resistors are carbon composition, it wouldn't be a surprise if they'd drifted high in 60 years. Since they only see DC, any suitable wirewound or metal film would be fine.

    If it were me replacing them, I'd use multiple resistors in parallel, because they're in the bleeder resistor current path.

    73 es GL de Jim, N2EY
     
  5. N2TC

    N2TC Ham Member QRZ Page

    That's what the original did. Have had the replacements on order for a couple of days. Should be here next week.
     
    N2EY likes this.
  6. N2TC

    N2TC Ham Member QRZ Page

    OK, so I jumpered the the bias terminals and things came to life. In fact, a little TOO lively. It had a parasitic and it started to fry one of the suppressors. Was able to make it go away by adjusting the plate tuning capacitor. Interestingly, I got the parasitic when the tuning capacitor was in the 80 meter area and it would stop with the control in the 10-15 meter area. The smoking suppressor phenomenon only occurred with one of the tubes and it occurred to me that there might something odd with respect to the interelectrode capacitances for that one tube. These are Russian tubes - USSR actually so they're old - that I only use in amps with upright tube mounting, Have some spares so I swapped out the one tube and the problem went away COMPLETELY, without respect to the tuning cap setting.

    In the process, I started getting an appropriate HV reading. Not sure why, but I'll take it. WIll still replace the HV metering resistors as well as all 4 parasitic chokes and then, hopefully, I'm good to go. Thanks everyone for your ideas and suggestions.
     
    N2EY likes this.
  7. N2EY

    N2EY Ham Member QRZ Page

    Excellent news!

    Note that the HA-10 doesn't have a tuned input circuit, and that the total filament-to-plate capacitance of four 811As is so high that neutralization is usually needed at the high end of the HF range.
     
  8. N2TC

    N2TC Ham Member QRZ Page

    Yes, it actually has a neutralizing capacitor. You set the distance between the plates during assembly and the manual states that no further adjustment is needed. If I continue to have issues, I can check the distance with my calipers or... ...maybe I should just do that anyway while I have it open.
     
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  9. N2TC

    N2TC Ham Member QRZ Page

    Replaced chokes and HV metering resistors and now even worse. Again meter doesn't move and now 2 of the chokes start smoking when HV applied. I have checked meter switch connections and cleaned the contacts, Focussing on HV, I read the correct t0-ground resistance for the metering resistor stack- from the + side of the meter and through the switch so I know that's working. The big bleeder resistor is fine too. One weird thing, I should be getting close to FS in HV meter poistion and HV on, which means about 0.05v from the juction of the bleeder/meter resitor stack to ground (50 ohms/1 ma). My multimeter, which does resolve that low shows no voltage reading at all there. Am I doing something wrong here? Independent check of HV with a high voltage probe and my DMM reads in the neighboirhood of 2 KV. One other thing I will do with respect to the parasitic is pull all of the Russian tubes and replace with made in USA
     
  10. N2EY

    N2EY Ham Member QRZ Page

    "chokes"?

    Do you mean parasitic suppressors? I'll assume you do.

    Something is shorted somewhere.

    The poor thing is probably oscillating at VHF because the Russian bottles have slightly different characteristics.

    What do you have connected to the amplifier output and input? The reason I ask is that, with the output and input just floating, and four tubes in parallel, there may be enough feedback through the tubes to cause the poor thing to take off, which wouldn't happen if the input and output were connected to 50 ohm loads or sources.

    Note that the HA-10 doesn't have a tuned input circuit. This is because the input Z of four 811As is fairly close to 50 ohms - well, close enough that almost all transmitters of those days could match it. But if nothing is connected to the input and the 811As are drawing plate current, all sorts of odd things can happen.

    73 es GL de Jim, N2EY
     

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