Re: Low Mic Gain, was, show your mic

Jerry Gaffke
 

Twiddling the bias pots is dangerous, can easily blow the IRF510's.
The bias pots get set at the factory for around 100ma of drain current
as described in the tuneup section on hfsignals.com.
Output will become more non-linear as those bias pots get turned down,
and quiescent transmit power consumption goes up as they get turned up. 
Not much of an effect on power out.  I suggest you not mess with them.

The drive pot at RV1 on the uBitx does directly affect power out,
also the resistor in the mike amp that Raj pointed out for you.

Be aware that too much drive to the final will splatter all over the band.

Jerry


On Sun, Apr 22, 2018 at 10:15 am, Skip Davis wrote:
Max your uBITX has three trim pots on it. Two are blue square unit labeled RV2 and RV3 these are together on the board and adjust the bias to the finals. The third one is RV1 which adjusts the drive level. There are instructions in the the file section on the group site to adjust the bias pots which may help improve your ssb output if yours isn’t set high enough.
Try searching the archives to learn about it and the pitfalls you might encounter.
 

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