SB-200 Damaged plate on "TUNE" capacitor

Discussion in 'Amateur Radio Amplifiers' started by KJ4AQU, Apr 1, 2012.

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  1. WA7PRC

    WA7PRC Ham Member QRZ Page

    Bad link. No image.

    Because others do something is not a reason in itself to copy them.

    I prefer to think that not adding unecessary hardware is a positive thing. We're not talking about Ameritron amplifiers. I've not tuned one so, I cannot comment on how it tunes.
     
  2. W1BR

    W1BR Ham Member QRZ Page

    Enjoy your stock SB-220. Specious arguments aside, while the SB-220 was a good design, there is a lot of room for improvement.
    For me personally, the improved plate tuning was one of the best improvements made on that amplifier.

    Pete
     
  3. KM1H

    KM1H Ham Member QRZ Page

    Thats an OEP clone of the Jackson 4511/DAF and also available direct from Ameritron and MFJ for decades. If you ask nice you can even get the pointer and mounting screws.

    Thats a very nice job Pete and the verniers certainly help.

    Carl
     
  4. KJ4AQU

    KJ4AQU Ham Member QRZ Page

    My previous reference about the HW-101 was that it used the Jackson drive on the main tuning knob. The Link about the vernier looks similar to it. I just thought adding one would make it a whole lot easier to tune 10 & 15.
     
  5. W1BR

    W1BR Ham Member QRZ Page

    We knew exactly what you meant. My friend, back in the sixites, had an HW-101 Heathkit. He did a mod where he adapted the venier
    dial drive and concentric tuning knobs from a popular Swan transceiver to the HW-101! Man, what a diference! I think it was written up in a ham magazine
    back then. Maybe 73??? It was a sweet modification, he loved it!

    Pete
     
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Swans had a silky-smooth 2-speed tuning mechanism with slow speed on the normal knob and fast speed on an outer one and it really worked well.

    I don't know how well they held up over 40 years since I don't have any Swans today and rarely even get my hands on one; but when they were new, they were terrific.
     
  7. WA7PRC

    WA7PRC Ham Member QRZ Page

    I remember those. It was handy to QSY fast, and then compensate for drift.
     
  8. AG6K

    AG6K Ham Member QRZ Page

     IMO one of the best single improvements for the SB-220 is a 15Ω - 20Ω, >110J glitch-R in the HV plus lead. The reason is that this resistor limits peak I and reduces the lateral EMF stress on the filament during the 220's intermittent VHF parasitic oscillation - avoiding a filament to grid short - usually on on V2.
     
  9. W1BR

    W1BR Ham Member QRZ Page

    Rich, did that.

    Pete
     
  10. KJ4AQU

    KJ4AQU Ham Member QRZ Page

    New tune cap installed and amp running better now! Yeah now I can sell it! Anyone interested?
     
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