[Elecraft] Split DX

[Tom Hammond]

Hi Brett:

>I've heard frequencies where it seems like nothing is going on and then all
>of the sudden 10 stations light up.  I'm assuming that this is a split DX
>and I'm only hearing half of it.

That's almost certainly what you're hearing... the end that the DX
station is listening to... called 'the piluep'...

>But anyway it doesn't make much sense to me.  So granted a station can
>listen to both frequencies at once and I'm sure transmitting station is
>probably only listening when he's not transmitting (unless he has two
>separate radios and two separate antennas).  This just seems like a
>waste of bandwidth especially if he's not doing full duplex.

It's a matter of the DX station being able to BE HEARD once a pileup of
callers has grown.

If the DX station is working everyone 'simplex' (e.g. on his transmit
frequency), it won't take long before many of the calling stations start
(0r continue) calling the DX station long after he has already picked out
a station and is attempting to complete a contact with that station.
However, due to the fact that a number of callers continue to call ON TOP
of the DX station, no one can hear the DX station, or at least can't hear
him well enough to complete the QSO... so everyone continues to call and
the DX continues to try to work (or pick out) a single station from those
calling ON HIS FREQUENCY.

If however the DX says he's listening "UP 5", "UP 10", or "Up wherever",
he then is able to move the callers (the pileup) off of HIS transmit
frequency, so that all the callers can hear him when he responds to a
calling station. Additionally, the pileup will naturally spread out a
bit (generally around a central listening frequency) so the DX operator
will be able to tune through the pileup, picking out individual callers
and (generally) working them at a much faster rate.

There have been really excellent ops in the past who could 'handle' an
on-frequency pileup as swiftly as those working split, but those ops are
few and generally far between.

The next effort for the DX operator is to not allow his pileup to become
1) too unruly, and 2) too widely spread out such that it covers too wide
an amount of the spectrum. Most times, a goos CW op can keep his pileup
mostly contained within 5-7 kHz without too much difficulty. The exception
sometimes being when it's a really rare country and there are (literally)
several hundred, or more, callers all screaming at once.

>Is there a common split distance so that one may easily find the other
>half or do people usually just go digging till they find it?

Generally "UP 5" is a very commonly used split. I believe the VP6DX crew
is using WIDE splits in order to keep THEIR signal well out of any QRM
from callers, and to keep it from being too close to the upper band edge
of the US extra class bands. They have been specifying splits which allow
all classes of licensee to call them... the calling split freq being
just a few kHz above the bottom of the General Class band segment.

73,

Tom Hammond  N0SS