GB3TD Frequency Change
The Swindon UHF repeater GB3TD
has been operational on the same frequency 433.075 Mhz and from the same site
since 1994 and is managed by the Ridgeway Repeater Group.
In recent years the repeater has
been suffering from interference in the form of clicking and pulsing noises and
also from wideband transmissions which can severely desence incoming signals.
The group has spent many hours
trying to determine the source of some of these without success.
OFCOM were consulted and tried
their best to identify the problem without actually finding it due to
restrictions gaining access to certain areas of private property.
The main interference to our
secondary use band is from 433Mhz to 435Mhz which emanates from low power
devices but also the MOD which is the primary user of the band.
When GB7TC our DMR repeater was
commissioned and co sited with GB3TD and using the same antenna, the filtering
system was complicated and caused extra losses in the system. Never the less
has worked well.
A question was asked to the RSGB
repeater committee asking if a 7.6Mhz wide band split would be possible for
GB3TD.
The RRG were asked if the group
would like to try a reverse shift to the normal Tx low Rx high configuration.
GB3TD output frequency will be
438.4375 and the TD receive will be 430.8375.
This was agreed and an NOV issue
to Rob, G4XUT.
The benefit is that the filtering
for GB3TD and GB7TC will be easier with less through losses with both Tx and Rx
being at the same ends of the band.
