Are these amp readings ok?

Discussion in 'Amateur Radio Amplifiers' started by KB4MNG, Aug 13, 2017.

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  1. KB4MNG

    KB4MNG Ham Member QRZ Page

    TS 520 with 50 watts in...

    Grid 110
    Plate 400
    Output about 650 w
    My mfj tuner meter show about 400 out.

    Ameritron suggest no more that 150 ma grid current in cw. How do you feel about that suggestion?

    AF6LJ likes this.
  2. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    What amp is this??
  3. KG7SWP

    KG7SWP Ham Member QRZ Page


  4. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    I would say the plate current is quite low.
  5. KB4MNG

    KB4MNG Ham Member QRZ Page

    Sorry, It's the al 80 a 3-500
  6. AC8AC

    AC8AC Ham Member QRZ Page

    don't sound too far off . haven't ran my al80 in a wile . I could just to show my readings
    KD2ACO likes this.
  7. AC8AC

    AC8AC Ham Member QRZ Page

    50w in
    375ma plate
    120ma grid
    625w out
    135ma idol
    fo 14.230

    using a bird 43 and 1kw bird dummy load . tube vintage 23 week of 1991 . original tube previous owner was 3 shy from earning his dxcc with this amplifier so tube seen a hard life . imho the al80a other than possible transformer issues is the best amplifier ameritron has ever made . I will never part ways with this amplifier

    I think components are perfectly sized for its design
    KD2ACO likes this.
  8. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    An AL-80B can handle 200mA grid current, 400mA continuous plate current (600mA peak).

    I drive mine with ~60-70W and LOAD it for 150mA grid current (limited by the ALC adjustment), and let the plate current be whatever it is -- never really look at that. It makes 1 kW output (not continously, but for the 5 seconds it takes to tune up) on every band. I keep the drive down to limit Ig to 150mA (although the tube can handle much more) and the output power to about 800W.

    There is no "idling current" with an AL-80B. I don't know about the AL-80 (original) which is very old. But the 80B has RF actuated biasing and it's fast as hell. You'll never see any idling current, it occurs only when the amp is driven. When just "keying" the amp without drive, the idling current is zero. This is a "feature" that helps keep the shack a bit cooler.:p
    AC8AC likes this.
  9. KB4MNG

    KB4MNG Ham Member QRZ Page

    I really like the al 80 a. I have replaced the chokes so it will work on the warc bands. Does great on 17 but seems to have problems on 12, Don't work that band anyway...
  10. AC8AC

    AC8AC Ham Member QRZ Page

    always thought they should have a jumper in the back for bypassing that system just to check idol current . there was a few that I repaired I added a resistor to keep that system from dropping the bias back . just to trouble shoot then lator removed resistor once repairs were complete . its a cool idea and it works . just with amplifiers I much prefer the KISS method

    the 80b is a nice amplifier just they made the case real thin and them cross needles grr . when I first licensed I was like yeah cross needle within a year I said these things have to go nice in a tuner cause who really pays any attention to what they say there just for quick reference needle on left high needle on left 0 or close to it and go

    most people ask me what is a good affordable amplifier and without any delay I say an al80b . anything below that forget it just wasting your money . transistors belong in the car not a ham shack
    N8VIL likes this.

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