Updated 5 August 2006
Radio Mirror International
Sundays: 08:00 UTC
Mondays 19:00 UTC
Listen to what PLC sounds like
Listen to a
report on interference in Rooiwal
to SARL main site
Report on Investigation
of R F I caused by PLC system at Rooiwal Township.
Listen to the
On Saturday 22 July 2006 at approximately
17:00 Paul Ras ZS6PR, Adanus Seymore ZS6AU and Marten du Preez ZS6ZY
drove to the Rooiwal Township to investigate the RFI caused by the PLC
system which has been installed in the Township.
The radio apparatus which was installed in Paulís vehicle is a ICOM 726
connected to a Hustler antenna with 80 and 40 M elements which was very
well matched with an SWR less than 1.2:1. The elements resonated at
3,640 and 7,060 MHZ.
The initial observation was done on 3,640 MHz . As we entered the
Township the interference increased to 9 +20 dB and remained at that
level as we drove around in the Township. Observations were made on the
corner of 4th and 8th Streets and the S meter still registered 9+20 dB.
We obtained an address in !st Street No.2 of a user of the PLC system
and he invited us into his house to have a look at the equipment used in
the PLC system and to demonstrate the operation there of.
He mentioned that the system is not operating completely satisfactorily
and that further improvements will be made. For instance only the modem
can be plugged into the specific 15 Amp socket since if a double adapter
is used for other equipment the system fails. He has to use an extension
cord from another plug in another room to supply power to the computer
We went back to the car and tried to contact George ZS6NE living in
Lyttleton on both 80 and 40 M but was unsuccessful due to the PLC
interference still registered at 9+20 dB. On 80 M we could hear there
was a signal but extremely weak so that no communication was possible.
However George heard us quite good from the car.
We drove off and observed that the interference decreased to about S2 at
a distance of 300 meters from the entrance of the Township and
thereafter no interference were heard. It was then possible to
communicate with George ZS6NE on 80 M. In order to establish that the
PLC interference could not be heard again, we drove for almost 3 km
northwards on the old Warmbaths road. We turned back and as we came
opposite the Township on the Warmbaths road the PLC interference could
again be heard although fairly weak. Thereafter the PLC interference
From the above report it can be concluded that a radio amateur living in
the Rooiwal Township and having installed well designed antennas for HF
operation will not be able to communicate on 80 and 40 M.
It is therefore requested that the SARL lodge a urgent complaint with
ICASA and that in depth investigation be done soonest. The outcome of
the investigation be made public and reasons forward why the Radio
regulation regarding harmful interference is not applied.
A recording of the interference in MP3 format will be made available.
Submitted by: Marten du Preez ZS6ZY
Paul Ras ZS6PR
Adanus Seymore ZS6UA
24 July 2006