Hi John (and all at the reflector)
Thanks for your answer.
I just grounded the mic jack housing following the guidelines I found on the
Elecraft web site.
No improvement however. I have tried different compressor settings (and
bypassing it) but this does not improve or worsen the audio.
When I hold the microphone about 1 foot from my mouth the audio seems OK but
of course I'm not putting much power out. Moving the mike closer to my mouth
the choppiness quickly becomes apparent. When I press my lips against the
mike it sounds slightly better although rather distorted, a bit like the
famous recording of the first man on the moon "A small step for man but a
giant leap for mankind".
I carried out my test on 40m. The thing that struck me also was that I got
very little ALC reading, only 1 bar lighting up occasionally. That one LED
didn't flicker along the rhythm of my modulation either. It just flickered
on and off in a quick fashion and stayed lit for about half a second after I
stopped talking.
I recorded my test a few minutes ago. If anyone wants to listen to this
recording in order to assess the problem, please drop me a mail and I'll
send the file.
Have a nice Sunday
73 de Glenn ON4WIX
----- Original Message -----
From: "John D'Ausilio" <[EMAIL PROTECTED]>
To: "ON4WIX" <[EMAIL PROTECTED]>
Sent: Sunday, April 09, 2006 5:41 AM
Subject: Re: [Elecraft] K2 s/n 5361 SSB TX audio problem
I had a crappy audio issue that turned out to be RF getting into the
audio .. there's some docs around that describe how to correctly
ground the housing of the mic connector, you might want to try those.
gl de w1rt/john
On 4/8/06, ON4WIX <[EMAIL PROTECTED]> wrote:
Hi all
I'm experiencing a funny problem with my K2 s/n 5361.
My KSB2 board went through intitial testing without problems, all
measured values were OK as per the manual.
My TX audio however is horrible. It sounds very choppy (one ham reported
to me it sounds 'very restrained'), it seems like the signal is cutting
out and then switching back on in a very rapid fashion. I get almost no
ALC reading when modulating, neither speaking very closely into the
microphone nor a few inches away.
At first I thought I was experiencing the well-documented low mike gain
problem. When speaking very closely to the microphone (a Kenwood MC43)
the audio sounds reasonably clear (distorted but not much gets chopped
out) but as soon as I move away from the microphone the chopping effect
kicks in. This led me to believe that my mike output level was too low
and that the KSB2's noise gate was operating on its gating threshold.
I then connected a preamp between the mike and the K2. With the K2
connected to a dummy load I listened to my TX signal through my Kenwood
TS570. Varying the preamp gain made no noticeable difference, the audio
kept sounding distorted.
I then tried the R14 mod (changing the 1k R14 into a 10k resistor). No
solution, still very crappy audio (I disconnected my preamp at this
stage).
At that moment I discovered a funny thing: when speaking into the mike at
a distance of approximately 1 foot I noticed that my audio was almost
sounding natural. Of course I was not getting any power out of the K2
this way. When I moved the mike closer to my mouth the distortion quickly
came back.
So, at this moment it looks like I'm grossly overmodulating when I speak
at a normal distance from my mike. It sounds a lot better when I speak
far away from the mike but then I'm really running QRPp, hi.
I've taken the KSB2 board out of the K2 and checked all soldering joints
(which seem OK). One of T2's leads looked suspicious so I desoldered T2
and rewound it with the little spare wire I had left and resoldered it.
Still no luck.
Receive audio is OK so the filters seem do be doing fine.
Any suggestions on where to start looking for the cause of this problem
are more than welcome.
Thanks in advance
Glenn ON4WIX
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