QSK CLICK

[Indy-3]

Seems like everyone's radio is a little different.  I have done the sidetone mods on my K2 and the tone quality is nice.  When I added the DSP a nasty pin-prick click occurred at the MAKE of QSK keying.  This is in monitoring only, it is not on the air.  This is much more pronounced with a pair of AKG K-100 hi fidelity headphones than with my old Heil pro-set, but the pro-set is not 35 ohms and audio with them is well down.

I did the AF pot mod, and that greatly improved audio artifacts which were somehow accentuated by the DSP.  With the RF gain down, the radio is dead quiet until the AF gain is nearly all the way up.

I have the new sigmoidal keying mod, it had no effect on this click.

I tried both Lyle's mod for slowing the mute line, and Wayne's mod.  Neither have any effect what so ever.

the time duration of the mute keying has no effect.  The click occurs at the make of the QSK, does not occur if the QSK does not drop out between characters, so the source is not the sidetone itself.

I put a .47 capacitor across the headphone to ground, no effect what so ever.

I have the low-pass filter from the KAF2 installed with the DSP.  The click is unchanged before and after that mod.

The click changes amplitude by varying the AF pot, a clue.

The click is present when the radio is in test mode and not actually keying the transmitter.

there is a very similar sounding click that occurs when the radio is turned on but that click is louder.  

There is a very similar click that occurs when I hit the band change button.  If I hit the band change button and change several bands before allowing the relays to change, the little pin-prick click occurs only with the first touch of the band-change button.  The tiny pin-prick click does not occur for the operation of most buttons, but ialso occurs with the NB button at each touch of it.  It also occurs at the break, not the make, of each operation cycling the pre/ATT button.  Sounds exactly the same for each of these cases and the keying, and for each, the amplitude of the click varies with the AF pot adjustment.

The click sounds like the kind of click you get when you apply a small DC voltage to a pair of headphones.  I don't think it is a timing issue.  I think that somewhere a capacitor is charged up and it is unloading its charge into the headphones at the make of the QSK.  Just maybe there is a place where I have an incorrect value like a 103 instead of a 104 or the opposite.

somebody can figure this out!!!

73

Fred
KT5X
K2 # 700

PS I rcv the digest so please copy me directly your thoughts!
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