Re: Low Mic Gain, was, show your mic

Skip Davis

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.

Skip Davis, NC9O 

On Apr 22, 2018, at 12:53, MAX <max@...> wrote:

Hi Raj.


I have the ubitx.  Thanks for the suggestions.  I see two trimming pots on the board but I haven’t touched them because I have no idea what they do.  It appears from your message that one is for adjusting the drive.  What is the other one for?




Max K 4 O D S.


I've Never Lost the Wonder.


Antique Electronics Site:



From: [] On Behalf Of Raj vu2zap
Sent: Sunday, April 22, 2018 4:54 AM
Subject: Re: [BITX20] show your mic



From board to board there will always be some variation of gain.

You can increasing the mic gain by reducing the resistor

BITX40 - R123
uBITX - R63

You could try the mic gain control I described recently.

You could also increase the drive

BITX40 - R136


At 21/04/2018, you wrote:

Speaking of mics, I have to raise my voice almost to the level of shouting to get 5 watts out on 40 meters.  Is this normal or should I look for a problem?
Max K 4 O D S.
I've Never Lost the Wonder.
Antique Electronics Site:

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