[Elecraft] K2: audio thumps and pops on key closure - is K1 app note relevant?

[Don Wilhelm]

John,

A long time ago, there were pops and thumps with keying in a few K2s 
having the KDSP2 and KPA100 options.  It was coming from the KPA100 T/R 
switch, and several changed capacitor values in the KPA100 to combat it.

Check your KPA100 - if it has red toroid cores at L15 and L16, then 
adding KPA100UPKT would be the first order of business.

I have not seen mention of a K2 parallel to that K1 mod - you could try 
it, but you would need two caps and two resistors - connect to the drain 
of Control Board Q7 and Q8.

73,
Don W3FPR

On 4/15/2012 12:56 AM, VK7JB wrote:
> Hello Group,
>
> I've been using my K2/100 on CW a bit lately and have noticed that there are
> low frequency thumps/pops on the receive audio at the rx to tx transition -
> ie onset of keying (key closure).  They are most noticable if the noise
> floor is high or if there are other signals in the receiver passband.  If I
> wind the RF gain right back or operate on a really quiet band and the
> artefacts disappear.
>
> They don't relate to the DSP (they occur even when DSP is bypassed), to the
> state of the 8R Hold parameter or to the presence or absence of transmitted
> RF (the artefacts are present also in TEST mode).
>
>