How I Tune Up My Amplifier

Discussion in 'Amateur Radio News' started by KM9G, Jul 7, 2021.

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  1. KM9G

    KM9G Ham Member QRZ Page

    Oh this should be fun, I've got my popcorn ready. New Guy, Old Amp, lets see if I can light it up real good!
    Come on boys, ROAST ME
    KA4DPO, KE5VDK, KC4XX and 14 others like this.
  2. NK7Z

    NK7Z Premium Subscriber QRZ Page

  3. AB0R

    AB0R XML Subscriber QRZ Page

    KE5VDK, KM9G and M1WML like this.
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    A few points:

    Since 811As cannot withstand anything more than about 260W continuous output (for four of them in the 811H), keep key-down times very short if running anything more than that; however, the most important things to watch are actually output power and grid current.

    Since "tuning" at 10W or even 25W drive will result in very different tuning points than when driving at full power, I've found the fastest and most efficient way to tune one is at "full power," by peaking GRID CURRENT (not plate current) with the PLATE control, then adjusting LOAD for maximum output power that results in <200mA (max) grid current. If when adjusting LOADing for max output, grid current exceeds 200mA, just turn the LOAD control more clockwise to increase loading and watch the grid current go down without impacting output power much.

    The full procedure should take ten seconds or less to achieve Po = 600W with Ig <200mA, and you're done.

    Step-tuning at lower power levels just wastes time, to me, since everything will need to be re-peaked at normal drive anyway.

    The 811H cannot safely produce 800W output power except perhaps PEP on SSB with a low duty cycle. Tuning up "fast" saves the tubes better than step-tuning.

    These guidelines can apply to "any kind" of tube amplifier. I tune my homebrew 4-1000A and 8877 amps the same way (and also my only "commercial" amp, which is an AL-80B).
    KA4DPO, MI0ODN, VA3QY and 13 others like this.
  5. K1LKP

    K1LKP Platinum Subscriber Platinum Subscriber QRZ Page

    KA4DPO and M1WML like this.
  6. WA1UIL

    WA1UIL Premium Subscriber QRZ Page

    Just like the Russian Hacker sez " B00M Guys"
    M1WML likes this.
  7. KO2Q

    KO2Q Platinum Subscriber Platinum Subscriber QRZ Page

    Last edited: Jul 7, 2021
    K8PJM, KA4DLT, W0ARM and 23 others like this.
  8. K4TAX

    K4TAX Premium Subscriber QRZ Page

    I wish more hams understood this and followed accordingly. Always tune/load for maximum output and then reduce the drive to attain desired operating power. Then DO NOT change or "re-peak" the amp.

    73, Bob -K4TAX
    WB9AZA, N5RK, W0ARM and 13 others like this.
  9. KT0DX

    KT0DX Ham Member QRZ Page

    What ever happened to Peak the Load and Dip the Plate?
    K6LPM, AA7ZZ, NU4R and 11 others like this.
  10. KY4GD

    KY4GD XML Subscriber QRZ Page

    NU4R, PU2OZT, K3RW and 5 others like this.
  11. VK7HH

    VK7HH Ham Member QRZ Page

    All knobs to the right TO!
    KT5OT, WA8MEA, W9FL and 3 others like this.
  12. M1WML

    M1WML Ham Member QRZ Page

    life,s to short for qrp... :D
    W0ARM, KJ7MX, N3FAA and 1 other person like this.
  13. N4CAX

    N4CAX Ham Member QRZ Page

    No, Just no.
    M1WML likes this.
  14. AB0R

    AB0R XML Subscriber QRZ Page

    VA3QY, M1WML, DL6SEZ and 1 other person like this.
  15. WA1UIL

    WA1UIL Premium Subscriber QRZ Page

    Yeah, I always spike the plate and tune for the bump so Bird Watts are at the max. "If the lights ain't dim'n..... you ain't pinn'n" Soon exams will be a matter of copy & paste and be sure to grab your participation trophy when exiting the Mc Donalds Playscape VE session.
    Last edited: Jul 7, 2021
    KQ1V and M1WML like this.

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