[Elecraft] [K3] Phase Noise / CW Key Clicks

[Matt Zilmer]

My case study may not be any less interesting than others you've
heard.  During Field Day, 2011 K3 #24 (mine) was the centerpiece of
our group's CW effort.  The group was a number of aligned clubs, and
we operated 12F (emergency operations center, 12 stations).  You can
imagine the HF overlap involved, since there were nearly always two
stations on one band but on different modes.  Our site was about 350
meters in diameter with stations around the outside edges and a couple
on VHF/UHF in the middle.

Dave, W3DMA, is also a K3 owner.  He and I were partnered on the CW
station.  We operated 19 hours out of the 24 allowed, for about 800
contacts.  This isn't awful, but it should have been better.  The main
cause of our CW count being so low was phase noise from other stations
on the same band at our site.  Many were running > 100W too.  That
WHOOSH Wayne mentioned wiped out a lot of received transmissions on
our end, and we had to constantly ask for AGNs due to a transient high
noise floor.  We could see that 15-20 dB rise of the floor on the P3
quite easily.  The screen went mostly white during those times.

Now - I KNEW better, but I went around to the other stations when they
were operating on same bands as the CW station (Dave at the key, were
at the computer).  They weren't hearing us AT ALL and didn't even know
we were on the same band!  Except for our roving spotter with a
broadband panadapter who could see my K3 but not hear it.  No key
clicks from us, but of course you could hear them all over the band(s)
from remote stations.

Phase noise and key clicks are the enemy.  I respectfully suggest that
Wayne emphasize (as well) that designing a transceiver to
intentionally not produce either of these is a worthy objective more
on a moral plane than an operating advantage.  Tactically, having
clicks and wideband noise could be put to advantage against other FD
groups.  As Wayne pointed out, phase noise may limit receiver
sensitivity (if it's not limited first by other factors), but most
hams have never thought about it that way.  I suspect, in practice,
that in other transceivers phase noise is not the limiting factor in
sensitivity - mainly because the front end design is shoddy compared
to the K3.  Front end noise figure is perhaps a larger factor in many
cases.

The main real-world problem is that the K3 is a minority in the
general ham rig population.  Maybe someday, the K3 penetration rate
will be high enough that we can hear it in how quiet the bands are.
Crowded but quiet between signals that is.
   
73,
Matt Zilmer, W6NIA / NNN0UET / NNN0GAF THREE
NMCM RMS Winmor: NNU9ET-5: Upland, CA.
NAQCC: 6081, 10-10: 10413, KX3 #6/FT