[hpsdr] Penelope Power Problem

[Bill Tracey]

I think the LED power meter on Penny actually measures the output 
power, so it would read lower if the OPA2674 is not putting out full power.

Regards,

Bill (kd5tfd)

At 02:48 PM 11/22/2010, John Petrich wrote:
>***** High Performance Software Defined Radio Discussion List *****
>
>Sorry to bother people, but Penelope suddenly dropped power output 
>from the nominal 500mW to about 220mW.  This happened following a 
>demonstration at the local ham club meeting.  Additional 
>observations are that only 4 of the 5 LED's will light with maximum 
>drive, and at the 220mW level, Penelope outputs picket fence IMD 
>spurs every 2 KHz @-30dBc and down.  Reducing the drive through the 
>PA Settings, Gain by Band menu, from "38" to"39" maintains the same 
>nominal 220mW output, but the IMD spurs disappear.
>
>Does anyone have a diagnosis?
>
>The 1/2 power output and IMD observation suggests to me that part of 
>the output amplifier, OPA26741 IC, has failed.  I cannot explain the 
>fact that only 4, instead of 5, LEDs will light with maximum drive.
>
>Any suggestions are appreciated.
>
>Regards,
>John Petrich, W7FU



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