Re: TDA2228M

Gordon Gibby <ggibby@...>
 

Here is RV1 in the circuit:

image1.png

It’s between two stages in the transmitter amplification series of 4 stages.



On Mar 13, 2018, at 21:35, ae1ct1998 <AE1CT1998@...> wrote:

THANKS FOR THE INFO MIKE. NOW CAN YOU TELL ME WHAT RV1 DOES? I KNOW RV2 AND RV3 ADJUST THE PA CURENT.

On Tue, Mar 13, 2018 at 2:42 PM, Mike Woods <mhwoods@...> wrote:
Did you adjust the BFO?  They come way off frequency with audio as you describe.  Press the rotary encoder button and select Settings.  Press again when display reverts l and select BFO calibrate in the menu.

Mike

On Wed, 14 Mar 2018 at 6:57 AM, ae1ct1998 <AE1CT1998@...> wrote:
I WAS GIVEN A MICROBITX 40 RADIO WITH A BLOWN TDA2228M CHIP. I REPLACED THE CHIP AND NOW I HAVE AUDIO BUT ITS VERY LOW AND THERES A HIS ON THE HEADPHONES, MY QUESTION IS DOES ANYONE KNOW WHERE I SHOULD LOOK TO TRY AND FIX THIS ISSUE. I CAN HEAR STATIONS BUT THERE IS NO MID OR LOW RANGE JUST HI'S. IVE TRIED TO FIND A SCHEMATIC FOR THIS RADIO ON LINE BUT THE ONLY ONE I CAN FIND IS PRINTED WITH VERY LITE INK, NOTHING READABLE. ANY HELP WOULD APRECIATED.

GARY
AE1CT


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