[minima] Re: mic audio routing into the audio amp : a bug
- From: Raj <vu2zap@xxxxxxxxx>
- To: minima@xxxxxxxxxxxxx
- Date: Sun, 09 Mar 2014 12:11:51 +0530
The leakage should be about 1/100th or 40db - should be liveable.
Another bug Farhan: There is DC leak path from the side tone oscillator emitter
which is direct coupled to the mixer. The DC level at the emitter if high
enough it will go through one diode and into the RFC. In any case the two
diodes will not be behaving identically if one has even a little forward bias
and the other will be slightly reverse biased.
Cheers
Raj, vu2zap
At 08-03-2014, you wrote:
>I noticed something today. there was a trace of my own audio on the earphones
>as i worked some stations on SSB the short opening on 14 MHz.
>
>then, looking at the circuit i realised that this is due to the cw sidetone
>generator. It has two 1K resistors one goes to the audio amplifier input and
>the other goes to the modulator output. Hence, there is effectively an audio
>path (however attenuated) between the mic and the audio amp during the
>transmit.
>
>we can take the side-tone output that goes to the audio amplifier from the CW
>side-tone's collector.
>
>alternatively, we can just live with this.
>
>what do you people vote for?
>
>- f
>
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