[Elecraft] K3 : SSB modulation

[Tom W8JI]

**Without using enough compression** (CMP), a lack of SSB average power 
level occurs because the ALC does not act the same in the SSB mode as it 
does in other radios. This makes the audio sound thinner or less powerful 
because there is less very short term (fast speed) compression to level 
voice amplitude peaks and valleys.

Using higher compression corrects this.

For example using a sample and hold Bird 4391 power meter (it stores the 
highest readings for later viewing), the highest (MAX) readings are:

FT1000MP MKV
no processing, normal ALC, peak to average power ratio 4.26:1
normal processing, normal ALC, peak to average ratio 3.85:1

K3
no comp, normal ALC, peak to average ratio 4.7
comp 20, normal ALC, peak to average ratio 2.84

The 1000MP is almost the same with or without processor
The K3 has a drastic improvement

I have not looked at waveforms on a scope, but this is what the 4391 Power 
Analyst says. It would be interesting to look at some speech patterns, but I 
have no idea what a good reference input would be or how to accomplish that. 
The above is with my voice and saying "hello test one two three" several 
times normally. :-)

I must use the CMP at 20 or more or the audio sounds thin. No amount of mic 
gain will correct this.

>From 4391 Bird meter readings and my ear I think this K3 behavior is proper, 
and the Yaesu actually is lacking because the ALC distorts the peak to 
average ratio too much. In the K3, the ALC is not a processor. In the Yaesu, 
the ALC acts as a processor.

73 Tom


>> After using mostly these rigs for SSB contesting in FY5KE or in other
>> places, we are still facing a lack of "dynamics", "punch",
>> "penetration", "power", whatever you call it. In other words, when
>> comparing this rig to our radios we previously used (TS-850), with the
>> same microphone (Heil HC-4 element) and the same output RF power, the K3
>> is clearly way behind in term of "average power" we can read on the Bird
>> wattmeter wired on its RF output. Even if observing the wattmeter needle
>> is not a very scientific measurement (we admit it), various comparative
>> reports on the air do confirm our feeling.