Technical Committee 2018 annual report

During 2018, we (generally myself and Jeff, K4OLW, with others also providing significant support) made 18 repeater site visits mostly to deal with audio drop out issues. This consumed countless man hours of effort dealing with Arcom as well as monitoring and testing possible solutions. In the end, we were able to replicate the issue on demand, so were able to help Arcom first propose a temporary workaround, then implement a software update that so far appears to resolve the issue.

The other major issue we dealt with was related to unsatisfactory audio over the link between 146.925 and 146.895. We first simplified the link topology by eliminating the link REPEATER at 146.895, replacing it with a half duplex link RADIO. This helped us understand the challenges of working with old/surplus/free Motorola GM300 radios. We then obtained some newer Motorola CDM750 radios with vastly improved audio and improved audio configurability and changed to DCS squelch on the link. This has resulted in much better link audio and link reliability.

We installed a better power backup solution at the Heard mountain site (146.760) using a West Mountain Radio Powergate instead of an AC “triggered” solution.

We updated the power supply at Martha Jefferson with a nice rack mount Astron 35 amp model from Roland Beard’s collection, and replaced the power supply at Heard Mt. With the Astron 35 amp supply originally purchased for and installed at Marshall Manor that I repaired and updated with much higher rated components.

In order to improve overall RF receive performance, we removed the Vertex VXR9000 from Sentara/MJH for repairs and updates, replacing it with the DR1-X that was previously providing the 444.250 service at that site. After performing the needed work on the VXR9000, we installed it at Bucks Elbow (146.895) which is a better machine for the high RF environment at that site. The clubs other DR1-X from Bucks Elbow is now at my shack awaiting another “assignment”. The clubs Kenwood TKR820 that was previously providing the link REPEATER functionality is now installed at Sentara/MJH on 444.250.

We also did significant work on the 224.760 repeater environment at Heard Mt. All components of the repeater were removed and tested/tuned, resulting in good reports from the users.


Bill, N0WP