Re: uBITX woes, feeling disheartened. #ubitx


M Garza <mgarza896@...>
 

There have been several threads discussing BCI filters that can be added to block the AM broadcast interference.  Search the messages, there have been suggested filters and schematics.

Marco - KG5PRT 

On Jan 4, 2018 5:53 PM, "Gordon Gibby" <ggibby@...> wrote:

Making progress.   Others here may have much more knowledge than I.


1.  The QRM:   is it recognizable voices?   Are you able to recongize the station and thus tell us the frequency they are on?


2.  Were there strong broadcast stations near you, or some other strong transmitter?


3.  You said the feedback when transmitting goes away when you turn down the volume control.   Does it last for more than 3 seconds?   If so, then it is either coming from Q70 or from "CWTONE".   You could disconnect the wire from the Raduino that goes to CWTONE in the schematic to eliminate that input and see if it remains, which would mean it comes from Q70.   Next you could measure the collector voltage on Q70 in transmit to see if for some crazy reason it is still getting power (which it shouldn't).   That would begin to allow you to work your way back on why the audio stages are still giving you signal when you shouldn't be hearing any in TRANSMIT.


If you're able to answer #1 above or help us know the FREQUENCY of the interference that would help.


Cheers!


Gordon




From: BITX20@groups.io <BITX20@groups.io> on behalf of nickpullen@... <nickpullen@...>
Sent: Thursday, January 4, 2018 6:16 PM
To: BITX20@groups.io
Subject: Re: [BITX20] uBITX woes, feeling disheartened. #ubitx
 
Hi,
a: When disconnecting the antenna the QRM goes away, but the noise floor also drops, right off, as expected?
b: Still get massive feedback into a dummy load., no QRM though

Thanks.

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