Friday, 27 September 2019

GB3TD Frequency Change from 18th Oct. - **** Action is required.****

Please be advised of the below frequency change notification for GB3TD. To complete this on Friday 18th Oct the repeater will be off-air for a few hours. We expect service to resume on the NEW frequency from 1pm.

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.

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