Re: annoying thumping sound

TNX for the info Keith..

I tried a 300 ohm 1:1 transformer to isolate the output but still hear the sound. It is even noticable using headphones or an amped speaker, (not going through a computer soundcard) so I suspect this is just normal CPU noise for the BC780?

It only is only noticible when scanning as the channels roll over. It not terribly loud, and hardly heard with the radios internal speaker. But using an amplified speaker or good headphones, it is hearable enough to be annoying.

Any other suggestions? Perhaps better filtering somewher e.g. for the CPU or scanning cct? 

Does anyone else hear this normally using an amplified speaker or good headphones ?

73
G.
 

--- In [email protected], Keith <kilowattradio@...> wrote:
>
> 
> 
> 
> On 6/24/10 4:16 PM, "gregtheham" <radiotrade@...> wrote:
> 
> > Is there any fix for the annoying thumping sound heard in the speaker as the
> > channels roll over when in scanning?
> > 
> > This is especailly a problem if using recording software as the "thumping"
> > often triggers the squelch on the recording program. Turning up software
> > squelch does not solve the problem, as it will then not open for signal audio.
> > 
> > This soft thumping noise is heard even if only one bank is being scanned. It
> > goes away if you are only monitoring one channel ...
> > I need to scan in convetional mode (no truncking)where it is happening..
> > 
> > Perhaps a change in a low frq audio filter cap may help?
> > 
> > TNX es 73
> > Greg
> 
> You have got a short. It could be from the serial port connection or the
> audio connection. You need to use a 1:1 audio transformer for the audio
> going to your computer.
> 
> -- 
> Best Regards, Keith
> http://home.comcast.net/~kilowattradio/
>