[Elecraft] 6 Meter Questions - OT

[Bill W5WVO]

Absolutely, Ed! This really should be understood clearly by 6m newbies with 
only HF experience. Sporadic-E is different than F2 in two important ways:

1) Sporadic-E is localized and dynamic. The sporadic-E "clouds", as they are 
called, are sometimes quite small and localized. And they move, sometimes very 
quickly. Consequently, you can't hear most of the people who are operating on 
the band at any one instant in time. Due to shifting sporadic-E conditions, 
signals can pop in or out very fast -- within minutes or seconds from "not 
there" to "S9+40" or vice-versa.

2) Sporadic-E is extremely efficient. Sporadic-E clouds are formed by 
high-energy horizontal wind shear at the E-layer boundary, and for this reason 
they are very planar and can be intensely ionized, not unlike a mirror. It is 
not uncommon for stations 1200 miles away to be 60 dB over S9 during extremely 
intense openings -- (and you may be surprised to learn that that guy is 
running 100W to a 3-element yagi at 20 feet).

People tend to self-channelize on 5 kHz spacing most of the time, but when an 
S9+60 signal pops up 5 kHz away, you had BETTER have a good tight roofing 
filter in your 1st IF. During the two annual summer VHF contests (ARRL, June, 
and CQ, July), extremely strong signals are literally choking a wide-open 6m 
band from 50125 up through 50200 and above, and as for the usual 5 kHz 
spacing... Fuhgeddaboudit!  :-)

Bill W5WVO


Ed Gray W0SD wrote:
> Mentioned is a sixth reason to my recent post of additional reasons
> besides contesting for a 1.8 filter for SSB.  Six Meter sporadic E
> signals can be very, very loud and band conditions often change
> rapidly so two stations very close to each can appear very suddenly
> through no fault of their own.  This is even more true during the VHF
> Contests if the band opens.
>
> The questions I will answer direct.
>
> 73,  Ed W0SD
>
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com