[Elecraft] K3 - 2.73/1.98 Clicks on Power On

[Enno, PF5X]

Hi all,

Same here as Stewart and I replied already on an older tread on the same
subject. Meanwhile I found out the following and forwarded that info,
including an MP3 recording of the various settings, to Lyle of the Elecraft
team, who responded to my post.


The procedure to reproduce this is very simple. Tune on a continuous signal
(e.g. in Europe we have a "rattle sig" on 7017.58, with strength S7~9.
Switch off K3. When switching the K3 on again you'll hear for a short
instance (0.1~0.2 sec) the signal without AGC and at 'default' BW => LOUD !
This is even visible because while the sig is that loud for this short
period the S meter is at 0. Then the S-meter comes up to the S7~9 level, the
audio goes to normal levels at the same time. Also the BW icon defaults at
500Hz (and I think the real BW as well) until the RX is ready and is set to
the last used BW.

OK, just did some further testing, very interesting:

1. BW_DSP=2.7kHz + 2.7kHz stock filter -> not audible effect
2. BW_DSP=2.1kHz + 2.1kHz filter -> effect audible but not very loud, sounds
as 'click'
3. BW_DSP=1kHz + 2.1kHz filter -> same as 2, bit louder.
4. BW_DSP=500Hz + 0.5kHz filter -> effect audible and loud
5. BW_DSP=250kHz + 0.25kHz filter -> effect audible and loud

The effect is not always as loud, it just depends how the power up switching
coincides with the (non-constant) signal.

I have the strong impression that somehow this is a receiver boot sequence
issue related to the default BW setting early in the boot sequence ...


Other relevant settings:

Available roofing filters:
FL1=2.7
FL2=2.1
FL3=<empty>
FL4=0.5
FL5=0.25

Frontpanel:
CW
AGC-F
SHIFT central
NB Off
NR Off

MENU:
AFX MD delay 5

CONFIG:
AGC-S 020
AGC-F 100
AGC THR 003
AGC SLP 015
AGC PLS nor
AGC HLD 000
AF LIM nor 030
AF GAIN HI
LIN OUT nor 015
SUB AF balance
SPKR+PH no
SPKRS 1 

<unqoute>

So you can test a bit for yourself with these settings and see if you can
reproduce this behaviour. I have not received an answer from Lyle yet, but I
am sure he is digging into this as I type this ...

-- Enno, PF5X



Stewart Baker wrote:
> 
> Hi,
> Since installing MCU 2.73. I have noticed that power on is
> accompanied by a number of loud, rather unpleasant clicks/clunks
> from the speaker.
> 
> 73
> Stewart G3RXQ
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