Lynn,

I have no verification, but the KX3 is "similar" (but not necessarily the same). Note that the KX3 voice calls for 5 bars on the ALC meter for voice, while the K3 calls for 5 to 7 bars. That says that there may be some difference.

We will have to wait for Lyle or Wayne to chime in with the real info on the KX3 ALC onset point.

In the meantime, I would suggest that the answer is "yes" set the KX3 audio for 4 bars and assume that is the "no ALC" point. The 5th bar would then indicate ALC is being activated.

The power control in the KX3 is similar to the K3, so if the audio level is too low, power creep will be the result.

BTW, for those using the K2, the situation is similar, but the K2 ALC meter does not have the "VU meter" scale at the low end. If the K2 ALC indicator flickers, it means ALC has occurred. For the K2, increase the audio until you see an ALC indication, and then back off until it is gone. The power control on the K2, K3 and KX3 are essentially the same - a closed loop system that attempts to produce the power output requested on the power knob. Most transceivers do not do this closed loop power control, but instead use an open loop system that depends on the drive level alone. That is why the traditional advice to use the audio drive level to control the power output works well with most transceivers, but it does not work well with Elecraft transceivers because they use a closed loop power control system. Only Elecraft and some commercial transceivers use this closed loop power control system.

73,
Don W3FPR

On 4/3/2013 5:53 PM, Lynn W. Taylor, WB6UUT wrote:
Is it safe to assume this is true of the KX3 as well?

-- Lynn

On 4/3/2013 11:47 AM, Don Wilhelm wrote:
Well, I 'thought' was in the manual, and it *should* be.

Lyle has explained several times here on the reflector (and he should
know, he designed it) that the onset of ALC action is at the 5th bar.
The bars below that do not indicate ALC action at all.

Due to the way the K3 controls power, if you do not have sufficient
audio, the K3 will increase power (thinking there is not enough drive)
and you will find your power drifting upward as you transmit.

So adjust for 4 bars on the ALC meter (that is *no* ALC) so your power
will be uniform throughout the transmission.  With the K3 you must have
sufficient audio drive to allow the power controls to work as they should.
Contrary to the advice given for most transceivers (which do not control
power in a closed loop), the K3 power will behave strangely if you use
that advice - which is to set the power for maximum and use the audio
drive to control the power output.  That just will not work with the K3.


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