[Elecraft] K3 Noise Transient measurements

[Don Wilhelm]

Mike,

The AGC thing may be why I don't hear it - Whenever I power on the K3 I 
most always have the dummy load connected to it.  I power on first and 
then select the antenna.

73,
Don W3FPR

Mike Scott wrote:
> I put an oscilloscope on the right external speaker (8-ohms) of my K3 and
> set up on 40M SSB @ 2.7 KHz bandwidth. The audio gain is at 9 O'clock. Band
> noise is high at S-7, no signals heard. I measured steady state and start-up
> noise transient voltages. Audio gain is set to Hi. 
>
> peak-to-peak noise in steady state is 0.3 volts
>
> peak-to-peak noise during start-up transient is 5 volts
>
> I compute this as a +24-dB start-up blast, very startling to hear
>
> On CW 400 Hz filter I get 0.3 volts and 3.5 volts peak-to-peak or +21 dB
> start up transient. 
>
> I believe that a signal or strong band noise needs to be present for this
> effect to be heard. I went to 10M with S-0 band noise and I can not measure
> or hear a startup transient at all. So if anyone tries to replicate this
> problem from a quiet location, better hook up a noise bridge.
>
> I believe that someone has noted that the effect has something to do with
> AGC. I believe this to be correct as I can get the same noise blast by
> turning the AGC off.
>
> AGC settings as follows (I believe all default):
> AGC Hold 000
> AGC PLS nor
> AGC SLP 012
> AGC THR 005
> AGC -F 120
> AGC -S 020
>
> Mike Scott - AE6WA
> Tarzana, CA (DM04 / near LA)
> K3-100 #508/ KX1  #1311
>
>
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