YAESU FL-2100B - Bias

Discussion in 'Amateur Radio Amplifiers' started by F8BDX, Nov 29, 2017.

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  1. F8BDX

    F8BDX Ham Member QRZ Page

    Hello to all OM
    I have 60mA of rest current
    I have the new 572B of RFparts
    is this correct or dangerous for Tubes?
    see the JPEG
    TNX Jose

    fl2100_8w.jpg
     
  2. G3YRO

    G3YRO Ham Member QRZ Page

    The standing current on Transmit should be around 90mA, so that is a little low. (but shouldn't be a problem). However, if I saw that, I would suspect that one of the Valves isn't working properly.

    You don't normally ever have to adjust the bias resistor if the Valves are OK . . . does the Amp work OK otherwise? What is the dipped PA current when tuned to maximum output into a Dummy Load on 80m? (and what power do you get?)

    It could also be that the meter is reading wrong, which would mean altering the meter shunt.

    If everything else is OK, you CAN adjust the bias if you want. It's the big green resistor under the chassis - you loosen the clamp to move it . . . to get more standing current, you need more resistance.

    Roger G3YRO
     
  3. F8BDX

    F8BDX Ham Member QRZ Page

    Good evening
    drive = 100 watts
    output = 550W, and the flat voltage drops from 2600v to 2000v
    73 Roger
     
  4. KA9JLM

    KA9JLM Ham Member QRZ Page

    In standby or keyed ?
     
  5. F8BDX

    F8BDX Ham Member QRZ Page

    Good evening
    40m
    drive 85W
    output= 580W
    73
    Jose in Nice
     
  6. G3YRO

    G3YRO Ham Member QRZ Page

    You should get at least 600 watts output on most bands . . . but that could just be error on your Power Meter. However . . . your HT Voltage is dropping a lot on load.

    Is your AC mains voltage OK? Does it drop much when the amp is on full power?

    Also, what is the dipped PA current when you have full power output?

    Roger G3YRO
     
  7. F8BDX

    F8BDX Ham Member QRZ Page

    Good evening
    yes Roger, 600W on all bands
    and even 700W over 40m.
    adjustable resistance for bias does not change when the position is changed.
    I tested the resistance on the whole length, it is ok
     
  8. G3YRO

    G3YRO Ham Member QRZ Page

    Do you mean that the Standing Current doesn't change when you move the tap on the Bias Resistor? (that doesn't make sense!)

    Also - you didn't answer my other questions.

    Roger G3YRO
     
  9. F8BDX

    F8BDX Ham Member QRZ Page

    Hello Roger
    40m Drive 100W = 600W output
    the 220v area does not vary.

    full power 600W, on the Counter A DC this gives 310 mA

    the Plate Voltage drops from 2400 to around 2050

    600W all Bands

    (Also, what is the dipped PA when you have full power output? - not understand the question)

    Jose 73
     
  10. G3YRO

    G3YRO Ham Member QRZ Page

    Hi Jose

    Well it sounds like it's working OK then, even though the Standing Current is a little low. (that may result in a little distortion on SSB - what do people say?)

    When any Amplifier is producing full output power, this should correspond to a slight Dip (= reduction") in the PA current (= Ic).

    So I was asking what the Ic reads when you have full power output?

    Roger G3YRO
     

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