From: "Mike Dennison" <mike.dennison@ntlworld.com>
To: rsgb_lf_group@blacksheep.org
Date: Sat, 20 Nov 2010 16:50:15 -0000
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Subject: LF: 136kHz Eu DX frequency - summary
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There have been 6 comments on whether the Eu DX slot on 136.320kHz is=20
still useful.  To summarise:

Grabbers: One more Eu station has provided a grabber on 136.320, and=20
one active NA station has stated he is unable to add this sub-band.=20
Only two grabbers are available outside Europe to monitor this=20
frequency - RW3ADB (which is almost always off), and KL7UK on demand.=20
It is therefore difficult for a Eu station to offer an occasional=20
beacon on the Eu sub-band as there=B4s nobody listening.

There have been two practical solutions to avoiding local QRM to DX=20
stations.

Split-frequency: This was used some years ago when there was lots of=20
Eu DX activity and east coast W/VE stations were monitoring.  For=20
instance, Eu transmit on 136.320 and NA transmit on 137.777.

Split timing: This was used successfully this year on the JA-VE=20
route. For instance, JA transmit on the hour and half hour, and VE=20
transmit on the quarter and three-quarter hour. A suggested solution=20
has been to use alternate days for Eu and NA.

Both of the above solutions are fine but they only work for two=20
locations at a time. If a third location is added to the mix, such as=20
Russia, or both East and West Coast America, the solution breaks=20
down. For instance, Eu transmits on 136.320, UA transmits on 137.777,=20
but NA also transmits on 137.777 and is prevented from receiving the=20
UA stations. A resolution would require at least three DX slots, with=20
every grabber equipped to receive them. The split timing solution=20
would also need additional timing slots which might lead to openings=20
being missed.=20

It is possible to devise a complex solution involving both time and=20
frequency, especially as the hours of darkness move round the world,=20
but it need all operators to cooperate.=20

Is there a real problem? I don=B4t think there is a practical problem=20
at present. Activity is low and most stations are in touch with each=20
other via this reflector. If/when the USA gets an allocation at=20
136kHz, I can see a real need for some kind of plan, but that=B4s not=20
for a while yet.

In the meantime, it is of course important for beacon operators to=20
make every effort to avoid interfering with each other. Frequency=20
spacing is an obvious way, as well as making sure that there are=20
listening gaps between transmissions. It would also help if more=20
grabber operators could open more receive slots.

To sum up my own position, I have not found any evidence of=20
propagation research or QSOs being affected by my occasional beacon=20
on 137.7752kHz, so I will continue to use this frequency. I will also=20
use 136.3182kHz whenever I can be sure there is a person or machine=20
available to receive my signals. I will also try to limit beacons in=20
time.

As always, if anyone has a practical problem, I am happy to switch=20
off.

Mike, G3XDV
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D