Yaesu FT-891 all radio with output power problem?

Discussion in 'General Technical Questions and Answers' started by UB8CGM, Mar 17, 2019.

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  1. UB8CGM

    UB8CGM QRZ Member

    My transceiver was released in December 2018.
    He has a problem, if i set the AM or FM modulation and press the PTT button, then the output power increases very slowly, in about 1 second.
    In SSB modulation, there is no such problem; power increases instantly.
    I checked 4 transceivers 891 and everyone has this problem.
    Check yourself, is there a problem?
    Here is a video showing the same problem.
  2. W1NB

    W1NB XML Subscriber QRZ Page

    Have you looked at this on a standard watt meter? The transmit power may actually be rising more quickly than the meter exhibits which would indicate it’s just the dampening on the meter. It appears from your video that the ALC meter exhibits the same dampening.
  3. KA9JLM

    KA9JLM Ham Member QRZ Page

    AM output rating is 25 watts.
  4. UB8CGM

    UB8CGM QRZ Member

    Not. Power increases very slowly everywhere, on any devices. And this is not a problem with my transceiver. This is the problem of many 891 transceivers.
  5. N3PM

    N3PM Ham Member QRZ Page

    Have an FT891 that does the same thing. DL and watt meter have noticeable rise time on AM and FM like the bar meter on the radio. Not there on SSB or CW.
    Mike N3PM
  6. KA9JLM

    KA9JLM Ham Member QRZ Page

    Must be soft start built in. o_O
  7. NN4RH

    NN4RH Premium Subscriber QRZ Page

    Is the actual power increasing that slowly, or is this just the meter ?

    Put a stand-alone power meter inline and see what it does.
  8. UB8CGM

    UB8CGM QRZ Member

    This is actual power. External meter shows the same.
    I think this is 891 hardware a problem...
  9. N5SMO

    N5SMO Premium Subscriber QRZ Page

    The 891 will do it the first time you PTT after changing bands. Must be some built in protection in case the SWR is high on the band you just switched to. I have not seen this documented anywhere, but mine does it too after changing bands.
  10. UB8CGM

    UB8CGM QRZ Member

    SWR? Changing ranges? Have you read the problem? How can the SWR change with modulation?
    Good. Connect 50 Ohm dummy load and will be the same.... Why? :)

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