By David (VA7SZ)


The VHF duplexer, which was removed for tuning during the previous visit (22 October), was reinstalled. VE7EGO VHF is now performing well and serves as a local backup to VE7RSS. Some users who don’t have line-of-sight to RSS may find EGO performs better for local QSOs.

A 12 Vdc to 5 Vdc converter was installed to power the Pi microcomputer from the newly installed batteries, and the router was also wired for 12V. This will provide more flexibility in case of a power outage - assuming the Internet is still accessible.

Both VHF and UHF repeaters are now in good shape for the winter.

Preparations For Site Visit

The six-can VHF duplexer was removed from EGO on the previous visit because it was out-of-tune. David took it to Ralph Olds’ (VA7NU) workshop where Ralph put his commercial vector network analyser to work and retuned it.

Ralph achieved a pass band loss of -2.3 dB at the transmit frequency of 147.38 MHz, and -89 dB of suppression at the receive frequency.

The pass band loss was -3.6 dB at the receive frequency of 147.98 MHz, with suppression of -86.5 dB at transmit frequency of 147.38 MHz.

The printouts in the appendix illustrate the duplexer’s before and after condition. 

Terry (VE7TRZ) put together parts for a 12Vdc to 5Vdc converter so that the Raspberry Pi microcomputer could be powered from the backup batteries. Also a cable was made up to power the router from 12Vdc. Terry also made a device to connect to the Pi so that we could have remote readout of battery voltage.

VE7EGO's Duplexer

Site Visit 26 October 2022

Paul (VE7KWA) and David carefully moved the duplexer to the site. Terry accompanied us in his own 4WD vehicle and despite the previous night’s rain the track was good.

The duplexer was installed and tests showed 18.6 W at the transmitter output, and 11.4 W leaving the duplexer into the antenna. This is a loss of 2.1 dB, which is perfectly acceptable and very close to the bench value measured by Ralph.

While inserting the power meter, one of the connectors on the jumper cable between the lightening arrester and duplexer literally fell off – it had been pushed on and never soldered! This was put right, as was another spare cable in the shack in the same condition. A cable may look perfect, but it is always best to carefully inspect and test. In fact, this cable may have contributed to some of the problems we had been experiencing with this repeater.

The three of us got to work rewiring the Pi and adapting an enclosure to take the power supply electronics. The modifications worked except for the battery voltage analogue to digital converter. Terry will find a solution to this problem ready for the next visit.

We removed some old equipment and tidied the bench, leaving at 3 pm after almost five hours on site.

On Air Tests

That evening David spoke to Ralph in Armstrong using just 0.5 W from a handheld, while Ralph used 5 W from his handheld. David also had a QSO with Doug (VE7VZ) who was using 5 W from his station in West Kelowna. The following day David got into the repeater from just west of Enderby using 5 W from a hand held.

Both VHF and UHF repeaters at EGO should now be good for the winter.


Upper graphs show power losses through the filter, lower graphs show SWR.

 Receiver side of duplexer after tuning


 Transmitter side after tuning


Receiver side before retuning


Transmitter side before retuning