Topband: The N2XE Beacon Tribune

[N1BUG]

On Monday 03 January 2005 02:02 am, Tom Rauch wrote:

> Now for the curious effect I observed.
>
> While I didn't spend a large amount of time listening to
> 80 and I never listened to 40 at all, I did notice one
> thing that I found interesting. Listening to the very low
> power transmissions on 80 meters I observed a very
> pronounced signal peak just before sunrise. The effect
> was very much like the effect called "search light" or
> "spot light" propagation. While the signal was largely in
> the noise and unreadable from 0900 Z  until 1120 Z, I
> observed a very clear "strong" peak between 1125 and 1135
> Z where the signal was the equivalent of  about a "559"
> or better DX report. By 1138 copy was back to nil with an
> increase that provided a short 2 minute long readable
> signal starting at 1143 Z . After 1145 Z that was it for
> the signal. I never really noticed this effect over the
> same path when power levels were higher and signakl
> levels stronger, although I'm sure the path loss went
> through similar variations. This is why even one dB
> sounds like a large change when signals are in the noise,
> and is meaningless with "579" signals.

While listening to the N2XE/B 80 meter tests over several 
nights I observed similar signal peaks, although at my 
location they were not associated with sunset or sunrise. I 
typically got several peaks some 2 to 5 hours after sunset. 
They were not always at the same times but always within 
that range. Although I have insufficient data to warrant 
any conclusion, the peaks appeared to occur significantly 
earlier on days with somewhat elevated geomagnetic activity 
and later during quiet conditions. Then I would hear 
nothing through the night until the last hour before 
sunrise when again I would be getting these peaks. The 
morning peaks typically produced stronger and more stable 
signals than did the evening peaks, but all were rather 
impressive in that the signal would go from nothing to very 
easily readable, remain so for a few minutes, then 
disappear into the noise again.

The affect was not unlike what we often observe on DX 
signals. In particular I have noticed this with VK3's on 
160m the past few weeks. I typically get good peaks an hour 
or more before my sunrise (long after sunset in VK3) where 
the signal is up for a few minutes, then gone or much 
weaker. The VK3's are consistently much weaker at my 
sunrise, if detectable at all.

73,
Paul,  N1BUG