[Elecraft] Dropping the Code Test

[Jim Wiley]

OK, guys, get ready to hate me. 


 Here in Alaska, (that's a bit North of Michigan, to our flatlander 
friends) - Aurora is the norm.  As in - every day, 365 days a year.  
Some days it's no big deal, some days it eats your lunch,  it's just a 
fact of life. 


As often as not,  SSB will get through when CW won't.  FACT - not a typo! 


Apparently, with rapid changes in path length, which is what is 
responsible for the waterey sound of classic aurora reflection 
propagation,  CW signals sometimes get lost in the process.  I think 
this might be because CW signals are on just one frequency, and the 
destructive effects of multipath (selective fading) can wipe out 
individual dits or dahs, making copy of CW problematic.  


SSB, on the other hand, occupies a comparatively wide channel, and has 
energy on any number of frequencies within that channel.  So, during 
times when aurora is very active,  SSB apparently gets through because 
it has a sort of built in frequency diversity.  If a hole gets punched 
in a SSB signal at one spot, there are still hundreds of adjacent 
frequencies that have an equal chance of being reinforced.  The net 
result is that SSB suffers from rapid shifts in tonal balance as the 
"notched out" frequencies shift rapidly within the SSB pass band, but 
enough energy still remains that copy is possible. 


You will note that I am not saying CW is totally disabled - often times 
enough gets through that the incomparable DSP unit that sits on your 
shoulders can make enough sense of what it gets to still come up with 
copy.  After all, VHF DX via auroral reflection is done all the time.  
But, and this is the important part,  there are indeed times when SSB 
gets through when CW cannot.  Man - what a disgusting idea.  <grin>


High latitude propagation is very  different from what most "South 48" 
hams take for normal.   It is nothing unusual for us to have total HF 
shutdowns lasting days on end.   Even when bands are not being wiped out 
by solar storms, we get caught between between lukewarm MUFs and 
elevated LUFs - we frequently have access to only one band - 20 meters - 
because we are caught  between the MUF / LUF squeeze, and even then we 
will hear only a few of the strongest signals.  My station is not all 
that bad either - I run a TH7 antenna at 75 feet.   When the band is 
open, I can use my K2,  but when it's ratty even my Mark 5 driving an 
ACOM 2000A may not be enough.


Oh well, there's always Pinochle


- Jim, KL7CC



EricJ wrote:

It is my understanding from a communication with WB8RCR, a member of the 
Michigan Net, that CW is used because of a geographical anomaly  . . . . .

<snip>