Reduce output below 5W with FT991

Discussion in 'General Technical Questions and Answers' started by DJ7ZZ, Sep 13, 2021.

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  1. WE4E

    WE4E Premium Subscriber QRZ Page

    You could also fake out the ALC input with a 9v battery and a pot.
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Using a resistive attenuator works okay. The very popular DEMI transverters are (or at least used to be) available for milliwatts of drive, or up to "many watts" of drive just by ordering the right model number, and the only difference was the "high power drive" models had a built-in attenuator.:p
    WA9SVD likes this.
  3. WA9SVD

    WA9SVD Ham Member QRZ Page

    MORE knowledge than trying to outsmart the transceiver's designers to reduce power?:confused:
  4. DJ7ZZ

    DJ7ZZ Premium Subscriber QRZ Page

    I had a look in the Service Manual, that it is "perhaps" possible to reduce power.
    Procedure Adjustment Output Power/ TXG Adjustment / PO Meter.
    I will try that adjustment and if it not work I go back to default.
    The Transverter has an max input of 2W. An Attenuator inside will also give a 4db signal reduction.
    The RX Path has to work without attenuation.
    I try the workaround and give results
    K0UO likes this.
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Unless your transverter is very unusual, the RX path with substantial attenuation should work fine

    Remember, the attenuator is in the IF path, not the RF path at VHF. Every transverter I've ever used or built had I.F. gain that was enough to overcome the loss of even a 10 dB attenuator in that path. That doesn't impact receiver "sensitivity" at all, but might make an S-meter read lower.
    N5HXR likes this.
  6. KA9JLM

    KA9JLM Ham Member QRZ Page

    Maybe true, But ALC is not a very good way to control RF output below normal operating power. It can work Half Fast.

    I would use a Attenuator and be done with it.

    No need to make it complicated.
    WA9SVD and N5HXR like this.
  7. IZ0MTW

    IZ0MTW Ham Member QRZ Page

    If you really want to mess up in the service menu the one you want is 16-10. That’s the 5w setting for 144 band and you should be able to bring the pwr down.
    You should know what you’re doing if you go in there though and you do it at your own risk.
  8. G8FXC

    G8FXC XML Subscriber QRZ Page

    Interesting... Do you know which seeing it is for 70cm? I've been experimenting at seeing up a personal echolink node and I really could do with less than 5w!

    Martin G8FXC
  9. IZ0MTW

    IZ0MTW Ham Member QRZ Page

    17-10 is 5w uhf band setting.
    By the way I believe when you change pwr setting the pwr meter should be adjusted accordingly if you want it to read properly but that’s not a big issue.
    And obviously you should then set the radio to 5w too ;)
  10. DJ7ZZ

    DJ7ZZ Premium Subscriber QRZ Page

    Hello, thanks all for the Posts. I set 16-10 in the Menue to an output to 3W. I measure it with a external Wattmeter and so I made a table with the exactly output with the transceiver settings.
    5W=3W 6W=4W and so on.
    Now it ist possible to use my Transverter and also my 2m Amp.

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