[Elecraft] K3 AFSK RTTY overdrive - no ALC

[Chad WE9V]

Jim,

Thanks.  I've seen and read your document previously.  Is there something
specific you are referring me to in your document that I already haven't
covered?  Let me recap and add a couple points of clarification:

* It's not an RF problem, as it still exists in TX TEST mode.
* I do not have a hum/buzz problem.
* I've used this setup on microphone inputs of other radios, no problem.
(FT-920,990,1000)
* I am using audio transformers.  "Expensive" solution, but it's worked in
the past.
* I am using a ~20dB pad between the soundcard output and iso transformer.
(5600/560ohm)
* Duplicate 20dB pad/iso xfmr are on both channels, other channel driving
FT-1000 no problems.  Swapping L/R channels has problem follow K3, not
cable.
* I have 1.25" braid bonding K3>computer>FT-1000.
* I can turn the soundcard output down very low (<20%), but I have to turn
up the K3 MIC to get any power output.
* Using my Heil headset directly into the K3, I use a MIC setting of 15 on
SSB to get 5-6 bars ALC with 0 CMP.  Using this same MIC=15 setting, I
adjust my soundcard output so that both the Volume Control and Wave control
are both 50%.  At this setting, I have no ALC and <50W output power (with
PWR set to 100).  I can increase MIC to about 21, where I'll have nearly
100W output, but only 2 bars ALC.  If I back of MIC only one step, to 20,
I'll be one bar less than 100W, and only one bar ALC.  If I increase MIC to
23, I get 3-4 bars ALC and the ticking noise.  This seems very sensitive,
and a difficult tradeoff between getting 100W output and having the ticking
sound (which I'm guessing is some sort of clipping/distortion).

Others have mentioned being able to use 5 bars ALC with AFSK RTTY.  I can't
get anything close to that.  I'd like to reduce the MIC/ALC/output power
tradeoff sensitivity.  I've typically left the MIC gain alone on my rigs,
and when running AFSK RTTY, I would adjust the soundcard output to get full
ALC reading with no compression.  It seems that I can't do that with my K3,
only getting 2 bars ALC, and there's a fine line (about 2-3 'clicks" on the
MIC gain) between full output power and ticking/distortion.

So I ask again, is there some specific idea you'd like me to try that I
haven't covered?

Chad WE9V


On Sun, Nov 23, 2008 at 3:19 PM, Jim Brown <jim at audiosystemsgroup.com>wrote:

> On Sun, 23 Nov 2008 11:37:17 -0600, Chad WE9V wrote:
>
> >Any ideas out there?
>
> Lots.
>
> http://audiosystemsgroup.com/HamInterfacing.pdf
>
> 73,
>
> Jim K9YC
>
>
>
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