On Fri, 2006-12-29 at 23:07 -0500, K4IA@aol.com wrote:
> Yes, that is correct - with the Orion, the lower power setting makes the ALC
> much more sensitive. Since the ALC has some lag and overshoot, you can't
> rely on the ALC alone to keep you from splattering. You have to adjust your
> audio drive (mic gain or PSK input level).
>
> Here's the part I don't get:
>
> No one has suggested you back down the SSB mic gain to reduce the drive on
> your Orion to an amplifier. Say I only need 50 watts drive - Am I supposed
> to
> reduce my mic gain to get there? Seems to me that would leave me with a
> thin under-driven sounding audio similar to someone who talks too quietly or
> too
> far from the microphone.
Nope, the power setting is ALL ALC threshold. Setting it for 50 watts
only makes the ALC work more, causing more compression. You have to cut
the gain before the ALC to whether its microphone gain or the Drive
control of a Yaecomwood to have the same amount of ALC action. Then what
you get is a signal that isn't any thinner, just half an S unit weaker
and on a receiver with good AGC (which leaves out some Icoms) no
difference in perceived level.
> I would think you would drive the audio fully and
> reduce the PWR control down to 50 watts. If I remember correctly, the
> instructions say the ALC should just flicker on voice peaks.
That's right. If the power control also dropped the exciter gain by the
amount it lowered the ALC threshold you'd have to do nothing and that's
certainly possible in the DSP but apparently not done in the Orions.
> That would never
> happen if you reduced the mic gain to lower your output.
If you depend on tickling the ALC to show the right audio level, you are
also asking for a bit of compression.
>
> And yet, some say to lower the power output with PSK, you should leave the
> PWR setting on 100w and reduce the mic gain to your target output.
Because in many radios any ALC action introduces more distortion in the
transmitted signal.
>
> I am away from home and don't have my Orion in front of me to try this out
> but it is making me very curious.
>
> k4ia
> Craig "Buck"
> Fredericksburg, Virginia USA
>
--
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer
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