[Elecraft] Free DV (digital voice as reported in QST-Aprilissue)

[Don Wilhelm]

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.
>>