Re: uBitx has a bit too crispy / semi-distorted audio even on low signal levels #ubitx #ubitx-help

Ralph Mowery
 


My receive and transmitted audio did not have much highs or lows in it.  The filter was only about 1700 Hz wide.  I changed the 5 capacitors from the crystals that are used for the filter from 100 pf to 82 pf ( think that is the standard value) and it widened out the audio range .  Probably should parallel some 5 or 6 pf capacitors across them to get about 85 to 88 pf as I did not have anything between a low 80 and the 100 pf.

That effects both the transmit and receive response, so you may want to make sure the transmit audio sounds about the same.

de ku4pt


On Thu, Jun 14, 2018 at 1:18 PM, Mike <rezycle.bin@...> wrote:

I have completed the uBitx and calibrated both frequency and BFO. The sensitivity appears OK. However audio has a strange crispy / semi-distorted sound to it.

I read the post from W3JDR https://w3jdr.wordpress.com/2018/04/11/ubitx-dynamic-range-improvement/#comment-1507  about biasing Q70 more strongly, however that only reduced the gain somewhat but didnt seem to help the crispy / semi distorted sound.

I have tried several headsets and a speaker. Same issue.

Anyone have any hints to what may be done to achieve better audio and get rid of that distortion effect?

_

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