I've had my K3 for a while now, and just this week tried it out on SSB.
Fortunately, my first contact was honest and bold enough to comment on
my audio, which he said was "muffled". At that point I decided to
investigate by transmitting 0.1 watt into a dummy load and listening on
a Ten-Tec Orion II via headphones with its filters fully opened and
flat receive equalization.
The audio indeed could be classified as "muffled". Furthermore, it also
sounded distorted, as thought the microphone gain was set too high.
Oddly, it was distorted independently of the gain setting.
I have not had a voice QSO on the K3 since that moment. The K3 transmit
audio, at least on 40 meter LSB, was horrid. I would not be overly
concerned, except that I tried another K3 with identical results. The
following list represents machine data as well as the various things I
have tried to resolve this.
- K3 relatively late serial number (45XX)
- Latest firmware from the Elecraft web site
- Tried multiple microphones; Elecraft MH2, Heil GM-5, Heil Goldline Pro,
Heil PR781
- Tried multiple microphone cables, all of which used high quality shielded
cable (Heilwire, actually)
- Tried microphones with and without a W2IHY 8-band equalizer inline
- I even read the K3 manual and tried adjusting the mic gain from zero on
up to the point of ALC kicking in (note: compression was off at ALL times)
- Tried both low and high mic gain range settings on the K3
- Bias settings were appropriate for the microphone used (on for the MH2,
off for the Heil mics)
- I (patiently) tried many combinations of transmit equalization settings,
including those for Elecraft from the Heil Sound web site ("All things
Elecraft")
- Plugged these microphones into a Ten-Tec Orion II and listened to the
audio on the K3. The Orion's audio sounded beautiful with *NO* adjustments!
- I have the 8-pole SSB filters on the K3. Offset is set to zero. I even
tried changing the offset a bit with only a little improvement (I mean VERY
little).
I was able to get rid of much of the "muffled" effect, but the audio was
still distorted, almost like a compressor set too high.
- Radio was tied to the usual station ground although at 100 mW I seriously
doubt RF feedback is a problem
- Radios are located a reasonable distance from the power supply (Astron
RS-35M, a linear supply). I've seen this affect audio in some rigs if too close
After all of the above, I have managed to achieve what I would call "almost
acceptable" audio. It's not the kind of audio
I want to inflict on others, however. I'm not looking to achieve "AM broadcast
quality" audio here; I just want my
SSB signal to sound clear and undistorted. Any help would be greatly
appreciated. Please bear in mind I tried out
two similarly equipped K3s; both performed identically.
By the way, LOVE the receiver in the K3. Nothing else comes close. Like my
K2, it can hear everything the Orion can, but with a SIGNIFICANTLY
lower noise floor. It also consumes much less current and precious shack real
estate!
Thanks and 73,
Bob WA4FOM
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