Since the statewide power blackout last year, AREG has been assembling replacement parts for the battery backup system on our VK5RSB repeater system. Now that this last weekends excitement is over, I am now able to compile and present a detailed report on the working bee at the VK5RSB repeater site at Summertown.

Working bee members,

• Ben VK5BB
• Colin VK5ACE
• Paul VK5BX
• Adrian VK5ZBR
• Rod VK5UDX (both Rod and Adrian were on an official task at the site in their employment but were able to spend time assisting at the site)
• David VK5MDF (invited visitor from NERC)

The aim of the working bee was to replace the cavities on the 23cm repeater, reinstate the battery backup system for the 70cm repeater (disconnected several years ago when the repeater was replaced with one requiring 24v input) and install (finally) the permanent replacement 6m repeater antenna (delayed multiple times in the past due to weather).

Work completed successfully included

23cm Repeater:

• 23cm duplexer fine tuned (thanks to Paul VK5BX and his Specan/tracking generator)
• the old 23cm removed and the new one fitted, tested into the antenna and live on air, all good

70cm Repeater

• the 12 volt to 28 volt inverter installed into rack and wired in,
• RF power out of 70cm when on battery backup has been set to 30 watts (normally 75 watts whilst mains power is active)
• repeater tested on battery backup, draws just on 8 amps and puts a “beep” every 60 seconds to identify unit running on battery backup.
• whilst on site, Paul took the opportunity to “Sweep” the VK5RSB 70cm antenna, return loss was good BUT it was identified that there IS a problem, a ringing or ripple on the return loss sweep, possibly due to a faulty connection in the line. We believe that the problem is most likely the coax connector on the top end of the LDF 450 coax, as this was not serviced or replaced when we changed and fitted the new antenna a couple of years back.This means another working bee, when the weather for working at the top of the tower is conducive.

6m Repeater

• during the above work activities, Adrian and Rod were able to swap out the old 6m repeater antenna and install the new antenna. Once the new antenna was connected, a return loss sweep was done and all looked very good.
• with the the 6m repeater reconnected to the antenna, it was still “going nuts” keying up very regularly on “spurious” Checks of the spectrum could not identify any specific signals the could be causing this other than the high noise floor. So Adrian wound the mute setting a bit higher and this fixed the regular intermittent keying of the repeater. (subsequent observations and reports are that the 6m repeater seems to be working very well and is generally quite when not being worked)

A big thank you to everyone who contributed to the work at VK5RSB. I am sure it will improve service for all amateurs in the greater Adelaide Metropolitan area.