[Elecraft] K3 original - ALC erratic

[Bob McGraw K4TAX]

I find that with my K3S,  a tone applied that is divisible by 500 {500 
Hz, 1000 Hz, 1500 Hz, 2000 Hz, 2500 Hz} or any tone likewise divisible 
by 600 or multiples there of will cause the ALC indication to fluctuate 
in a rhythmic pattern.   Changing the tone frequency as little as +/-3 
Hz resolved the fluctuation appearance of the ALC  and thus presents a 
steady indication of ALC level.

73

Bob, K4TAX


On 9/16/2019 7:34 AM, Martin Sole wrote:
> I don't propose to know the full details but I would assume that being 
> an SDR the K3 digitises the audio at some point. If the sampling rate 
> and the audio frequency have the right relationship then you can 
> expect to see those fluctuating effects. I have seen this when making 
> distortion measurements on AM radios since the sampling rate and the 
> mod are not phase locked these odd aliasing type effects occur. Moving 
> the modulation frequency even just a few Hz is usually enough to 
> achieve a rock steady reading.
>
> Martin, HS0ZED
>
>