Re: in the adjustment menu i can not get the driver idle current down to the 1 amp setting


davebb123456
 

Hi Steve
Thanks for the info,
Like I said I am getting full output power now, but the data sheet does say it is a 60w item, so that is probably why I am still seeing 35w, but I do want it as it should be, so I will change the UHF output, 
And and then do the set up as in the manual,
Thanks for your help,
Thanks Dave, 2E0DMB

On Mon, 25 Apr 2022, 17:15 Steve W3AHL, <w3ahl@...> wrote:
Dave,
The UHF Idle Current definitely needs to be set to 2.5 amps for minimum distortion and spurious emissions.  I would suggest replacing the UHF PA FET.  There are other possible causes, but diagnosing them would be more difficult that replacing the PA.  

Setting the Idle Current establishes the FET's operating set point so that the positive and negative peaks of the RF signal aren't clipped.  There is no or minimal signal applied (thus the term "Idle"), so ALC should not be an issue.  

If you do replace the UHF PA FET, you will should perform all of the TX adjustments for the UHF band, since the newer FETs seem to have different gain than the original ones used, in my experience.  This requires applying the correct audio drive signal at seveal different levels.

Steve, W3AHL

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