[Elecraft] SSB low output

[Dale Boresz]

Hello Brian,

I've done a lot of experimenting with my K2 and the Heil HC5 element, 
and I think that some of the reasons for the many degrees of success 
using this element are related more to voice charactersitics than to 
anything else.

The first thing to note is that the Heil HC5 has been deliberately 
designed to require relatively close talking.

The rest of this is conjecture, but until I hear a better explanation, 
I'm sticking to it  :-)

Some folks (and I count myself among them, unfortunately) seem to have a 
higher than normal peak-to-average amplitude variation in their voice. 
As many have mentioned, you may find that indeed your ALC indicator 
shows that you are hitting 100 watts on voice peaks, however your 
average level may be very low - possibly as little as 10 watts or so. 
Unfortunately, very little usefull intelligence is transmitted during 
those 100w voice peaks so they aren't a whole lot of use.

Additionally, the K2's compressor chip includes a noise gate, so a 
"knee" exists at the point where the action changes from noise gate to 
compressor. Below the knee, input from your microphone is actually 
attenuated (the assumption is that any low-level noise is probably 
undesirable background noise). Above the knee, it is amplified, although 
held below some maximum level. My normal speaking voice is probably 
lower, both in amplitude and pitch than lots of folks, so what ends up 
happening is the peaks continue to hit the 100watt level, and unless I 
shout, much of the rest of the level from the microphone ends up being 
below the knee and therefore attenuated. Also, the HC5 rolls off the low 
end rather quickly, so if your voice is lower-pitched to begin with, a 
lot of the energy from your voice won't make it past the element anyway.

After much experimenting, including the building of a second KSB2, I 
ended up building the single transistor amplifier, the circuit diagram 
of which is available on the Elecraft website. This amp completely 
solved the problem. I now have plenty of audio, and have received quite 
a few compliments on the audio quality. So, my suggestion to you, is to 
take the time to build up that little preamp; you won't be disappointed.

By the way, I now have two microphones with HC5 elements; one amplified, 
and the other 'stock'. I'd be happy to set up a sked if you'd like, so 
that you can hear the difference between the amplified, and 
non-amplified HC5 elements.

73, Dale WA8SRA