Topics

TDA2228M

ae1ct1998 <AE1CT1998@...>
 

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

Dale Brooks KG7SSB <kg7ssb@...>
 

Try this one, I think it prints a fairly clear drawing.
Dale Kg7ssb

On Tue, Mar 13, 2018 at 10:57 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


Dale Brooks KG7SSB <kg7ssb@...>
 

Sorry about that I thought you were asking for the BITX40 schematic. I don't have a copy of the ubitx.
Dale

On Tue, Mar 13, 2018 at 11:12 AM, Dale Brooks <kg7ssb@...> wrote:
Try this one, I think it prints a fairly clear drawing.
Dale Kg7ssb

On Tue, Mar 13, 2018 at 10:57 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



w7hd.rh <w7hd.rh@...>
 

Did you mean TDA2822M?   That is in the ubitx transceiver (80-10M).  The bitx40 is a totally different radio, but isn't called a microbitx. 

If you mean the ubitx transceiver, you can find help here: 

    http://ubitx.net/

and original documentation here:

    http://www.hfsignals.com/

with a good schematic and individual areas explained here:

    http://www.hfsignals.com/index.php/ubitx-circuit-description/

and the fix for the audio getting blown, see the attached PDF.

Ron W7HD

On 03/13/2018 11:12 AM, Dale Brooks KG7SSB wrote:
Try this one, I think it prints a fairly clear drawing.
Dale Kg7ssb

On Tue, Mar 13, 2018 at 10:57 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


-- 
Ron W7HD - NAQCC#7587 OMISS#9898 KX3#6966 LinuxUser#415320
Editor OVARC newsletter

Jerry Gaffke
 

Here's a schematic:  http://www.hfsignals.com/wp-content/uploads/2017/12/ubitxr3.png

You might try adjusting the BFO within the menus.
See step 3, "Setting the BFO":  http://www.hfsignals.com/index.php/ubitx-tuneup/

The VFO does not track while moving the BFO, so any incoming station quickly becomes unintelligible.
So set the BFO for lower frequencies, then leave the menu (by hitting ptt) and retune.


On Tue, Mar 13, 2018 at 10:57 am, 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

Arv Evans
 

Scroll to the bottom for the uBITX schematic.

_._

On Tue, Mar 13, 2018 at 11:57 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


Mike Woods
 

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

ae1ct1998 <AE1CT1998@...>
 

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


Mike Woods
 

RV1 is used to set the drive level.

M


On Wed, 14 Mar 2018 at 2:35 PM, 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


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